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Intramolecular photo[4+2]cycloaddition of an enone with a benzene ring |
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Journal of the Chemical Society, Perkin Transactions 1,
Volume 1,
Issue 1,
1997,
Page 77-84
Keiki Kishikawa,
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摘要:
J. Chem. Soc. Perkin Trans. 1 1997 77 Intramolecular photo[4+2]cycloaddition of an enone with a benzene ring Keiki Kishikawa,* Satoshi Akimoto Shigeo Kohmoto Makoto Yamamoto and Kazutoshi Yamada Department of Materials Science Faculty of Engineering Chiba University 1-33 Yayoi-cho Inage-ku Chiba 263 Japan N-Benzoyl-N-benzylcinnamamides 1 N-acetyl-N-(1-benzyl)cinnamamides 3 and N-[(1-benzyl)- aminocarbonyl]-N-(1-benzyl)cinnamamides 5 have been irradiated by a high-pressure mercury lamp in the presence of benzil in benzene at room temperature to give 3-azatricyclo[5.2.2.01,5]undeca-8,10- dien-4-ones 2 4 and 6 with high stereoselectivity. These are the first photo[4+2]cycloadducts of an enone and a benzene ring. Photo-[2+2]- and -[3+2]-cycloadditions of alkenes to benzenes are typical reactions of the latter and many examples have been reported.1 In contrast photo[4+2]cycloaddition of benzene is much rarer the only known examples being photocycloaddition with dienes,2 furan3 and dichlorovinylene carbonate;4 such reactions showed low selectivity and gave poor product yields.Similarly photo[4+2]cycloadditions of enones are rare compared with the numerous examples of [2+2]cycloadditions with dienes; the only known examples of the former are the cycloadditions of enones with cyclopentadiene and furan;5 however both [4+2]- and [2+2]-addition showed poor selectivity. In order to achieve the hitherto unknown photo[4+2]cycloaddition of an enone with a benzene ring we designed intramolecular photo[4+2]cycloadditions of the cinnamamides 1 3 and 5. According to MM2 calculation,6 the [4+2]adduct 2a is 6.6 kcal mol21 more stable than the [2+2]adduct 2a9 and 102.8 kcal mol21 more stable than the [3+2]adduct 2a0.In these reactions the [4+2]adducts 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4- ones 2 4 and 6 were obtained as the sole products with perfect regio- and stereo-selectivity. The photo[4+2]cycloaddition of a benzene ring and an enone is novel although the [4+2] process is symmetry allowed from (i) the excited ethene (S1 or T1) with the S0 benzene or from (ii) the triplet excited benzene with S0 ethene.1h,7 Even thermal [4+2]cycloaddition of an enone to a benzene ring is very limited highly strained benzenes being required to react with reactive dienophiles.8 An enone fixed rigidly and closely to a diene moiety was reported by Wollenweber to undergo an intramolecular diene/ enone photo[4+2]cycloaddition from the excited state in a stepwise radical reaction.9 Aoyama et al.also reported an intramolecular photo[2+2]cycloaddition of an alkene and a benzene ring connected with a CO]N bond.1d If the 2- and 3-carbons of an enone are close enough to the carbons at the 19- and 49- position of the benzene ring respectively a diradical generated from the excited enone must react with the carbons at the 19- and 49-positions to give a [4+2]adduct (Fig. 1). Based on this idea we planned to hold the enone double bond in an N O O Ph R N O O Ph R H H H 2a' 2a" P16/01710J/B1 appropriate position for [4+2]cycloaddition by linking it with a rigid and planar CO]N]CO bond to the benzene ring. To suppress polymerisation of the acryloyl group a phenyl group was introduced at its 3-position.The cinnamamides 1a–p were prepared by condensation of the corresponding acid chlorides and amines. The irradiation was carried out in benzene with a triplet sensitiser (benzil) using a high-pressure mercury lamp under an Ar atmosphere at room temperature. Cycloaddition of the cinnamoyl double bond to the benzoyl-benzene proceeded to give the [4+2]adducts 2 (Table 1). In the reaction of 1a (R1 = R2 = X = H) the cycloaddition was attempted with several sensitisers [anthracene (ET = 42 kcal mol21) benzil (ET = 53 kcal mol21) naphthalene (ET = 61 kcal mol21) benzophenone (ET = 69 kcal mol21) and acetophenone (ET = 74 kcal mol21)]; direct irradiation failed to induce any reaction. Benzil was found to be the only sensitiser for the photo[4+2]cycloaddition the others sensitising trans–cis isomerisation of the cinnamoyl function.10 The reason why benzil alone sensitised the reaction has yet to be clarified.However it is obvious that the reaction proceeds from a triplet excited state because of sensitisation by the triplet sensitiser (benzil). Photo[2+2]cycloaddition of maleic anhydride to benzene is known to be a triplet state reaction when the charge-transfer complex is sensitised by benzophenone the unsensitised process arising from the singlet state of the charge-transfer complex.7,11 In all cases perfect stereochemical control was achieved the stereochemistry being determined by NOE difference spectra (1H NMR spectroscopy). The selected data are shown in Scheme 1 and indicate the trans-configuration of the 5- and 6-protons.Although trans–cis isomerisation was observed by 1H NMR analysis during the irradiation the stereochemistry of the 5- and the 6-protons in the tricyclic products 2 was trans. The UV spectra of 1a and 2a were measured in acetonitrile at room temperature (Scheme 2). The peaks at 250–350 nm disappeared after the cycloaddition. Methoxy nitro and cyano substituents on the benzoyl function [1b 1i (X = MeO) 1g 1m (X = NO2) and 1l (X = CN)] resulted in complete suppression of the cycloaddition with recovery of Fig. 1 Mode of photo[4+2]cycloaddition N O O R N O O R h n 4' 3 1' 2 1 2' 3' 3 2 4' 1' 2' 3' 1 P16/01710J/A1 78 J. Chem. Soc. Perkin Trans. 1 1997 starting material. In the reactions of 1 the cinnamoyl group reacted with the benzoyl group but not with benzyl. The electron density of the benzoyl group might control the reactivity.The stereoselectivity of the cyclisation is controlled by the steric repulsion between the phenyl and carbonyl in the cinnamoyl group. In the case of 1h 1n 1o and 1p the regioselectivity of the cycloaddition was deduced from the reaction of the deuteriated compounds the benzoyl group being replaced with [2H5]benzoyl (1h9 1n9 1o9 and 1p9) difficulties being experienced in determining the stereochemistry of the products by 1H NMR spectroscopy. In the 1H NMR spectra of the adducts (2h9 2n9 2o9 and 2p9) the signals for the protons at the bridgehead-carbons (C-7) and the double bond-carbons (C-8 Scheme 1 NOE spectra of photo products (selected data) N H H H H Ph H H O O Ph R1 R2 N H H H H Ph H H O Me O H Ph N H H H H Ph H H O N O H Me H Ph Me H 2h (R1=Me R2=H) 2a (R1=H R2=H) 2n (R1=Et R2=H) 2h (R1=Me R2=H) 2p (R1=Me R2=Me) 2o (R1=Ph R2=H) 2a (R1=H R2=H) 2n (R1=Et R2=H) 2o (R1=Ph R2=H) a b 2% 2p (R1=Me R2=Me) 4% 2% 3% 3% 2% 3% 2% 3% 6b 4b 7% 4% 2% 2% 12% 3% 1% 2% P16/01710J/B2 Table 1 Photo[4+2]cycloaddition of 1a–pa Ph O N O R1 R2 X N O O Ph H R1 R2 X 2a-p 1a-p hv /benzil in benzene at RT 1 2 3 4 5 6 7 8 9 10 11 P16/01710J/B5 Entry Starting material R1 R2 X Time (h) Product Yield (%)b 1 1a H H H 3 2a 93 2 1b p-MeO 16 2b 0 3 1c p-Me 2 2c 99c 4 1d m-Me 1 2d 83 5 1e o-Me 2 2e 35 6 1f p-Cl 6 2f 71 7 1g p-NO2 18 2g 0 8 1h Me H H 2 2h 99c 9 1i p-MeO 8 2i 0 10 1j p-Me 2 2j 99c 11 1k p-Cl 4 2k 92 12 1l p-CN 8 2l 0 13 1m p-NO2 8 2m 0 14 1n Et H 1 2n 87 15 1o Ph H 1 2o 98 16 1p Me Me H 1 2p 84 a A solution of 1 (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated by a high-pressure mercury lamp under Ar atmosphere at room temperature.b The yields are isolated yields. c The yield of products was determined by 1H NMR spectroscopy of the solution. The products were thermally unstable. C-9 C-10 and C-11) disappeared as a result of replacement. The results indicated that the benzoyl reacted with the cinnamoyl function. In order to investigate the reactivity of the benzyl group in the photocycloaddition the benzoyl group was changed to an acetyl group (Table 2). The reaction of N-acetyl-Nbenzylcinnamamide 3a (R = H) failed to give the [4+2]adduct 4a under similar reaction conditions. In contrast N-acetyl-N- (diphenylmethyl)cinnamamide 3b (R = Ph) produced the adduct 4b in low yield.The products were expected to be a mixture of diastereoisomers because of the three asymmetric centres. However the single diastereoisomer 4b was obtained and its structure was determined by NOE difference spectroscopy (Scheme 1). The a-substituent of the benzyl group might have some important role for the reactivity and the stereoselectivity. Irradiation of N-cinnamoyl-N,N9-bis(1-phenylethyl)- ureas 5b–e (R = Me) also gave single diastereoisomers (NOE of 6b is shown in Scheme 1) [4+2]adducts 6b–e; however Fig. 2 UV spectra of 1a and 2a. Concentration = 1.00 × 1025 M solvent = acetonitrile and temperature 20 8C. 200 250 300 350 l /nm 20000 e /dm3 mol –1 cm–1 15000 10000 5000 1a 2a P16/01710J/A2 Scheme 2 Mechanism for the intramolecular photo[4+2]cycloaddition Ph O N O R1 R2 N O O Ph H R1 R2 X X Ph O N O R1 R2 X N O O Ph H R1 R2 H X * C 2 1 hv /benzil 3 B 3 * Heat P16/01710J/B3 J.Chem. Soc. Perkin Trans. 1 1997 79 N-cinnamoyl-N,N9-dibenzylurea 5a (R = H) was inert under similar conditions of irradiation (Table 3). In our previous report type II photocyclisation was observed in the reaction of N-acryloyl-N,N9-bis(1-phenylethyl)ureas to give b-lactam derivatives. 12 Thus a 3-phenyl substituent on the acryloyl group completely suppressed the hydrogen abstraction ability of the enone double bond. These results indicate that the a-substituted benzyl group is also reactive with the cinnamoyl group. In the case of 3b and 5b–e it is clear that the cinnamoyl group was excited by the sensitiser (benzil) to generate the diradical which reacted with the benzyl group since the benzyl aromatic ring itself is not excited by benzil.As with these reactions for compound 1 it also seems that benzil sensitises the cinnamoyl group which reacts with the benzoyl. The mechanism for the photo[4+2]cycloaddition was postulated as follows (Scheme 2). The cinnamoyl group of 1 is excited by irradiation in the presence of benzil (a triplet sensitiser) to give the diradical B. The symmetry-allowed photo[2+2]cycloaddition of an excited maleic anhydride–benzene complex (the triplet state) takes place because the face of the maleic anhydride-double bond and that of benzene smoothly interact. However in the reaction of 1 3 and 5 the face-to-face interaction for charge transfer 7,13 is difficult because of the rigid junction and stepwise cyclisation occurs.The stepwise [2+2]cyclisation of 1 3 and 5 needs a larger energy than the [4+2]cyclisation (from the MM2 calculation). The radical at the 2-position (more reactive than that at the 3-position),14 reacts with C-19 of the benzene ring to generate the spiro intermediate C. The methoxybenzoyl group (X = MeO) is not reactive Table 2 Photo[4+2]cycloaddition of 3a,ba 4a-b 3a-b hv /benzil in benzene at RT Ph O N R Me N O R Ph H O O Me P16/01710J/B6 Entry Starting material R Time (h) Product Yield (%)b 1 3a H 3 4a 0 2 3b Ph 2 4b 42 a The same procedure in Table 1. b Isolated yields. Table 3 Photo[4+2]cycloaddition of cinnamoylureas 5a–e 6a-e Ar O N O N O O R Ar H R N H R N H R 5a-e Ar = 4-XC6H4 hv /benzil in benzene at RT P16/01710J/B7 Entry Starting material R X Time (h) Product Yield (%)b 1 5a H H 15 6a 0 2 5b Me H 4 6b 56 3 5c MeO 6 6c 55 4 5d Me 4 6d 56 5 5e Cl 4 6e 61 a A solution of 5 (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated by a high-pressure mercury lamp under an Ar atmosphere at room temperature.b The yields are isolated yields. because an electron-rich benzene ring is an unsuitable acceptor of radicals. Suppression of reactivity by the nitro- and cyanogroups (X = NO2 and CN) is explained in terms of the unreactivity of the diradical in the generated diradical C which is stabilised by the electron acceptor groups. In C the a-proton is located cis to the phenyl group because of steric repulsion. In the photoreaction of N-(a-substituted benzyl) cinnamamides 3b and 5b–e the intermediate E is more favoured than D because of the steric repulsion between the R and the benzyl group (Scheme 3).In the photoreaction of a vinylene carbonate and benzene (Scharf et al.4) the initially generated [2+2]adducts are gradually transformed to the corresponding [4+2]- adducts. Accordingly the [2+2]adducts may be produced from the intermediate C at an early stage. However from the result of MM2 calculation the [2+2]adducts are less stable than the [4+2]products and their formation was not detected by monitoring with 1H NMR spectroscopy (Fig. 3). The trans–cis isomerisation occurs followed by the [4+2]cycloaddition during the irradiation. Some of the cinnamamides showed the thermal retro- [4+2]addition at room temperature (i.e. 2cÆ1c t1/2 = 3 h). The stereochemistry of the recovered cinnamamide 1c was the trans-form only.Reconstruction of the conjugated system must be the driving force for the retro reaction. The intramolecular cycloaddition of a benzene ring in cinnamamides gives only the [4+2]adducts and does not produce other by-products ([2+2]- and [3+2]-adducts). Now we are studying its utilisation for the photosensitive materials. Experimental General Mps were determined on a Yanako MP-S3 melting-point apparatus and are uncorrected. 1H NMR (270 400 500 MHz) and 13C NMR (22.4 67.8 MHz) spectra were recorded in CDCl3 or C6D6 and were referenced against internal tetramethylsilane. Chemical shifts are reported in ppm on the d scale. Coupling constants (J) are given in Hz. High-performance Fig. 3 Monitor of photo[4+2]cycloaddition of 2a. A solution of trans-1a (0.03 mmol) and benzil (0.03 mmol) in [2H6]benzene (1.0 ml) in a Pyrex tube was irradiated by a high-pressure mercury lamp (450 W) under an argon atmosphere.The percentages of trans-1a cis-1a and 2a were monitored by 1H NMR spectroscopy. 0 4 8 12 16 20 24 28 20 40 60 80 100 Yield (%) Irradiation time/(min) trans -1a cis -1a 2a P16/01710J/A3 Scheme 3 Diradical intermediates generated from 3b (R = Ph R9 = CH2Ph) and 5b [R = Me R9 = CONHCH(CH3)Ph] D (disfavoured) E (favoured) O N H Ph R R' O N H Ph R R' P16/01710J/B4 80 J. Chem. Soc. Perkin Trans. 1 1997 liquid chromatography (HPLC) was performed on Merck Lichrosorb Si 60 column (7 mm) eluting with ethyl acetate– hexane. Flash column chromatography (ethyl acetate–hexane) was performed with Fuji silica gel BW-200 (200 mesh). Photoreactions were carried out using a USHIO 450 W high-pressure mercury lamp.All solvents were freshly distilled and stored over 4 Å molecular sieves. N-Alkylcinnamamides and N-alkylbenzamides were prepared from the corresponding commercially available amines and acid chlorides. General procedure for the preparation of the cinnamamides 1 and 3 To a solution of N-alkylcinnamamide (1 mmol) in benzene (20 ml) was added triethylamine (1.2 equiv.) at room temperature. To the resulting solution was added dropwise the appropriate acyl chloride (1.2 equiv.). The resulting mixture was heated at reflux for 24 h after which it was quenched with saturated aqueous NaHCO3 (20 ml) and washed with 1 M hydrochloric acid (20 ml) and brine (20 ml). The organic layer was dried (MgSO4) and concentrated in vacuo. The products were separated by column chromatography on silica gel and further purification by recrystallisation from ethyl acetate–hexane or HPLC gave the cinnamamides.N-Benzoyl-N-benzylcinnamamide 1a. Colourless crystals (64%); mp 115–116 8C (Found C 80.9; H 5.5; N 4.4. C23H19- NO2 requires C 80.9; H 5.6; N 4.1%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.30 (1 H d J2,3 15.0) 7.10–7.65 (15 H m) and 7.55 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 49.2 (t) 121.6 (d) 127.5 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 128.8 (d) 130.2 (d) 132.6 (d) 134.4 (s) 136.3 (s) 137.5 (s) 143.4 (d) 169.3 (s) and 173.4 (s); vmax(KBr)/cm21 1695 1655 1620 1350 1205 1190 1140 and 705. N-Benzyl-N-(p-methoxybenzoyl)cinnamamide 1b. Colourless crystals (40%); mp 81–82 8C (Found C 77.7; H 5.7; N 4.0. C24H21NO3 requires C 77.6; H 5.7; N 3.8%); dH(270 MHz; CDCl3) 3.80 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 6.90 (2 H d J 9.0) 7.15 (2 H dd J 2.0 and 7.5) 7.20–7.35 (6 H m) 7.40 (2 H dd J 2.0 and 7.5) 7.55 (1 H d J2,3 15.5) and 7.65 (2 H d J29,39 9.0); dC(22.4 MHz; CDCl3) 49.3 (t) 55.5 (q) 114.1 (d) 121.6 (d) 127.4 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 130.1 (d) 131.3 (d) 134.6 (s) 137.7 (s) 142.9 (d) 163.3 (s) 169.2 (s) and 173.0 (s); vmax(KBr)/cm21 1650 1610 1340 1310 1255 1170 and 1035.N-Benzyl-N-(p-methylbenzoyl)cinnamamide 1c. Colourless crystals (84%); mp 113–114 8C (Found C 81.0; H 5.9; N 4.2. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.35 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 7.10– 7.45 (12 H m) 7.55 (1 H d J2,3 15.5) and 7.55 (2 H d J29,39 10.0); dC(22.4 MHz; CDCl3) 21.6 (q) 49.2 (t) 121.7 (d) 127.4 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 129.0 (d) 129.5 (d) 130.2 (d) 133.5 (s) 134.6 (s) 137.6 (s) 143.1 (d) 143.5 (s) 169.3 (s) and 173.5 (s); vmax(KBr)/cm21 1695 1655 1620 1345 1310 1185 1135 980 760 and 700.N-Benzyl-N-(m-methylbenzoyl)cinnamamide 1d. Colourless crystals (53%); mp 76–77 8C (Found C 81.0; H 5.9; N 3.9. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.30 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 7.10 (2 H dd J49,69 2.0 and J49,59 8.0) 7.20–7.45 (12 H m) and 7.55 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 21.2 (q) 49.1 (t) 121.7 (d) 125.9 (d) 127.4 (d) 127.8 (d) 128.2 (d) 128.5 (d) 128.6 (d) 129.2 (d) 130.1 (d) 133.2 (d) 134.4 (s) 136.2 (s) 137.6 (s) 138.7 (s) 143.0 (d) 169.3 (s) and 173.6 (s); vmax(KBr)/cm21 1695 1655 1620 1345 and 1165.N-Benzyl-N-(o-methylbenzoyl)cinnamamide 1e. Colourless crystals (48%); mp 94–95 8C (Found C 81.0; H 5.8; N 3.8. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.30 (3 H s) 5.10 (2 H s) 6.50 (1 H d J2,3 15.0) 7.10– 7.40 (14 H m) and 7.55 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 19.3 (q) 48.4 (t) 121.0 (d) 125.9 (d) 127.4 (d) 127.6 (d) 127.9 (d) 128.3 (d) 128.4 (d) 128.6 (d) 130.1 (d) 130.9 (d) 131.2 (d) 134.4 (s) 136.3 (s) 137.4 (s) 143.4 (d) 169.3 (s) and 173.2 (s); vmax(KBr)/cm21 1695 1655 1620 1345 1310 1190 1145 1045 and 975. N-Benzyl-N-(p-chlorobenzoyl)cinnamamide 1f. Colourless crystals (23%); mp 121–122 8C (Found C 73.5; H 4.7; N 3.7. C23H18NO2Cl requires C 73.5; H 4.8; N 3.7%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.35 (1 H d J2,3 15.0) 7.20 (2 H dd J 2.0 and 8.5) 7.25–7.40 (8 H m) 7.40 (2 H d J29,39 8.5) 7.55 (2 H d J29,39 8.5) and 7.60 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 49.1 (t) 121.0 (d) 127.5 (d) 127.9 (d) 128.0 (d) 128.5 (d) 128.7 (d) 128.9 (d) 130.0 (d) 130.4 (d) 134.1 (s) 134.5 (s) 137.2 (s) 138.7 (s) 144.0 (d) 169.0 (s) and 172.3 (s); vmax(KBr)/cm21 1700 1650 1615 1335 1310 1185 1135 and 975.N-Benzyl-N-(p-nitrobenzoyl)cinnamamide 1g. Colourless crystals (21%); mp 107–108 8C (Found C 71.5; H 4.4; N 7.4. C23H18N2O4 requires C 71.5; H 4.7; N 7.3%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.50 (1 H d J2,3 15.5) 7.25–7.40 (m 10 H) 7.60 (1 H d J2,3 15.5) 7.75 (2 H dm J 9.0) and 8.25 (2 H dm J 9.0); dC(22.4 MHz; CDCl3) 44.8 (t) 119.9 (d) 123.7 (d) 127.6 (d) 127.7 (d) 128.0 (d) 128.7 (d) 128.9 (d × 2) 130.8 (d) 133.8 (s) 136.8 (s) 141.8 (s) 145.7 (d) 149.3 (s) 169.0 (s) and 171.4 (s); vmax(KBr)/cm21 1695 1655 1615 1530 1345 1310 1185 865 and 715.N-Benzoyl-N-(1-phenylethyl)cinnamamide 1h. Colourless oil (98%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 6.06 (1 H q JN-a,N-b 7.0) 6.11 (1 H d J2,3 15.5) and 7.00–7.70 (m 16 H); dC(22.4 MHz; CDCl3) 17.4 (q) 54.7 (d) 122.5 (d) 126.8 (d) 126.9 (d) 127.4 (d) 127.9 (d) 128.3 (d) 128.4 (d) 129.8 (d) 130.1 (d) 132.2 (d) 133.9 (s) 136.9 (s) 140.7 (s) 142.3 (d) 168.7 (s) and 173.0 (s); vmax(neat)/cm21 1660 1625 1380 1340 1305 1275 1195 1070 765 and 700 [Found MH+ (FAB) 356.1657. C24H22NO2 (MH+) requires 356.1650]. N-(p-Methoxybenzoyl)-N-(1-phenylethyl)cinnamamide 1i. Colourless oil (74%); dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.0) 3.80 (3 H s) 6.00 (1 H q JN-a,N-b 7.0) 6.15 (1 H d J2,3 15.5) 6.85 (2 H dm J29,39 9.0) 7.10 (2 H dd J 2.0 and 8.0) 7.20–7.35 (6 H m) 7.45 (1 H d J2,3 15.5) 7.50 (2 H dd J 2.0 and 8.0) and 7.65 (2 H dm J29,39 9.0); dC(22.4 MHz; CDCl3) 17.8 (q) 55.1 (d) 55.3 (q) 114.0 (d) 122.5 (d) 127.0 (d) 127.2 (d) 127.7 (d) 128.1 (d) 128.2 (d) 128.6 (d) 129.4 (s) 129.9 (d) 131.4 (d) 134.4 (s) 141.0 (s) 142.2 (d) 163.3 (s) 168.6 (s) and 172.9 (s); vmax(neat)/cm21 1694 1648 1622 1602 1342 1306 1260 1200 1168 788 and 760 [Found MH+ (FAB) 386.1762.C25H24NO3 (MH+) requires 386.1756]. N-(p-Methylbenzoyl)-N-(1-phenylethyl)cinnamamide 1j. Colourless oil (99%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 2.30 (3 H s) 6.05 (1 H q JN-a,N-b 7.0) 6.10 (1 H d J2,3 15.5) 7.05 (2 H dd J 1.5 and 8.0) 7.15–7.35 (8 H m) 7.40 (1 H d J2,3 15.5) 7.50 (2 H dd J 1.5 and 8.0) and 7.55 (2 H dm J29,39 8.0); dC(22.4 MHz; CDCl3) 17.7 (q) 21.4 (q) 55.0 (d) 122.6 (d) 127.0 (d) 127.2 (d) 127.6 (d) 128.1 (d) 128.5 (d) 129.0 (d) 129.3 (d) 129.9 (d) 134.3 (s) 140.9 (s) 142.3 (d) 143.5 (s) 168.8 (s) and 173.3 (s); vmax(neat)/cm21 1694 1658 1620 1450 1374 1338 1306 1272 1196 and 1176 [Found MH+ (FAB) 370.1806.C25H24NO2 (MH+) requires 370.1807]. N-(p-Chlorobenzoyl)-N-(1-phenylethyl)cinnamamide 1k. Colourless oil (91%); dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.0) 6.05 (1 H q JN-a,N-b 7.0) 6.10 (1 H d J2,3 15.5) 7.10 (2 H dd J 1.5 and 8.0) 7.20–7.40 (8 H m) 7.40 (1 H d J2,3 15.5) 7.50 (2 H dd J 1.5 and 8.0) and 7.55 (2 H dm J29,39 8.5); dC(22.4 MHz; CDCl3) 17.6 (q) 54.9 (d) 122.1 (d) 127.0 (d) 127.6 (d) 128.1 (d) 128.5 (d) 128.8 (d) 130.0 (d) 130.1 (d) 133.9 (s) 135.3 (s) 138.6 (s) 140.6 (s) 143.1 (d) 168.7 (s) and 172.0 (s); vmax(neat)/cm21 1696 1652 1620 1340 1192 1172 and 758 [Found MH+ (FAB) 390.1270.C24H21NO2Cl (MH+) requires 390.1261]. N-(p-Cyanobenzoyl)-N-(1-phenylethyl)cinnamamide 1l. Colourless oil (66%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.5) 6.05 (1 H q JN-a,N-b 7.5) 6.15 (1 H d J2,3 15.5) 7.10 (2 H dd J 1.5 and 8.0) 7.25–7.40 (7 H m) 7.50 (2 H dd J 1.5 and J. Chem. Soc. Perkin Trans. 1 1997 81 8.0) and 7.65–7.75 (4 H m); dC(22.4 MHz; CDCl3) 17.6 (q) 54.8 (d) 115.2 (s) 117.4 (s) 121.7 (d) 126.9 (d) 127.7 (d) 128.3 (d) 128.6 (d) 128.7 (d) 130.6 (d) 132.2 (d) 133.6 (s) 140.3 (s) 140.7 (s) 144.3 (d) 169.1 (s) and 171.4 (s); vmax(neat)/cm21 2225w 1654 1340 1274 1192 1174 788 762 and 700 [Found MH+ (FAB) 381.1605.C25H21N2O3 (MH+) requires 381.1603]. N-(p-Nitrobenzoyl)-N-(1-phenylethyl)cinnamamide 1m. Colourless oil (65%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 6.05 (1 H q JN-a,N-b 7.0) 6.20 (1 H d J2,3 15.5) 7.15 (2 H dd J 1.5 and 7.5) 7.25–7.45 (7 H m) 7.50 (2 H dd J 1.5 and 7.5) 7.75 (2 H dm J29,39 9.0) and 8.20 (2 H dm J29,39 9.0); dC(22.4 MHz; CDCl3) 17.6 (q) 54.8 (d) 121.4 (d) 123.7 (d) 126.9 (d) 127.4 (d) 127.8 (d) 128.4 (d) 128.7 (d) 129.0 (d) 130.6 (d) 133.6 (s) 140.2 (s) 142.4 (s) 144.7 (d) 149.2 (s) 169.3 (s) and 171.2 (s); vmax(neat)/cm21 1656 1622 1526 1350 1306 1274 1190 848 792 760 714 and 700 [Found MH+ (FAB) 401.1503. C24H21N2O4 (MH+) requires 401.1502]. N-Benzoyl-N-(1-phenylpropyl)cinnamamide 1n. Colourless oil (95%); dH(270 MHz; CDCl3) 1.05 (3 H t JN-b,N-g 7.5) 2.30 (1 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 14.0 and JN-b,N-g 7.5) 2.50 (1 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 14.0 and JN-b,N-g 7.5) 5.80 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 6.05 (1 H d J2,3 15.5) 7.00 (2 H ddd J 1.5 1.5 and 7.5) 7.16–7.50 (10 H m) 7.55 (2 H ddd J 1.5 1.5 and 7.5) and 7.65 (2 H ddd J 2.5 3.0 and 8.5); dC(22.4 MHz; CDCl3) 11.6 (q) 24.6 (t) 61.8 (d) 122.9 (d) 127.2 (d) 127.6 (d) 128.0 (d) 128.5 (d) 128.6 (d) 128.8 (d) 130.0 (d) 132.4 (d) 134.1 (s) 137.2 (s) 140.1 (s) 142.4 (d) 169.5 (s) and 173.1 (s); vmax(neat)/cm21 1696 1656 1620 1338 1192 1176 788 760 and 698 [Found MH+ (FAB) 370.1804.C25H24NO2 (MH+) requires 370.1807]. N-Benzoyl-N-(diphenylmethyl)cinnamamide 1o. White solid (32%) (Found C 82.3; H 6.0; N 3.2. C29H23NO2?1/3H2O requires C 82.3; H 5.6; N 3.3%); dH(270 MHz; CDCl3) 6.15 (1 H d J2,3 15.5) 7.05 (2 H dd J 1.5 and 8.0) 7.15–7.50 (17 H m) and 7.70 (2 H ddd J 2.5 4.5 and 8.5); dC(22.4 MHz; CDCl3) 63.8 (d) 122.6 (d) 127.4 (d) 127.8 (d) 128.2 (d) 128.6 (d) 128.8 (d) 128.9 (d) 129.0 (d) 130.2 (d) 132.8 (d) 134.3 (s) 137.1 (s) 138.9 (s) 143.2 (d) 169.0 (s) and 172.8 (s); vmax(KBr)/ cm21 3050 2930 1695 1660 1620 1340 1190 985 765 and 695.N-Benzoyl-N-(1-methyl-l-phenylethyl)cinnamamide 1p. Colourless oil (73%); dH(270 MHz; CDCl3) 1.85 (6 H s) 6.20 (1 H d J2,3 15.5) 7.10–7.65 (13 H m) 7.45 (1 H d J2,3 15.5) and 8.05 (2 H ddd J 1.5 3.0 and 8.0); dC(22.4 MHz; CDCl3) 29.3 (q) 62.9 (s) 121.5 (d) 125.0 (d) 126.4 (d) 127.7 (d) 128.2 (d) 128.5 (d) 129.0 (d) 129.8 (d) 130.1 (d) 133.8 (d) 134.4 (s) 136.6 (s) 142.7 (d) 147.2 (s) 166.2 (s) and 174.8 (s); vmax(neat)/cm21 1700 1662 1622 1344 1268 1232 1158 784 764 and 698 [Found MH+ (FAB) 370.1813.C25H24NO2 (MH+) requires 370.1807]. N-Acetyl-N-benzylcinnamamide 3a. Colourless crystals (26%); mp 92–93 8C (Found C 77.4; H 6.0; N 4.9. C18H17NO2 requires C 77.4; H 6.1; N 5.0%); dH(270 MHz; CDCl3) 2.50 (3 H s) 5.05 (2 H s) 7.05 (1 H d J2,3 15.5) 7.20–7.40 (8 H m) 7.50 (1 H d J 7.5) 7.50 (1 H d J 7.5) and 7.75 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 26.0 (q) 47.5 (t) 120.1 (d) 126.2 (d) 127.3 (d) 128.1 (d) 128.7 (d) 130.3 (d) 134.4 (s) 137.0 (s) 145.0 (d) 169.1 (s) and 173.4 (s); vmax(KBr)/cm21 1700 1610 1380 1340 1195 and 1085. N-Acetyl-N-(diphenylmethyl)cinnamamide 3b. Colourless oil (99%); dH(270 MHz; CDCl3) 2.40 (3 H s) 6.70 (1 H d J2,3 15.5) 7.10 (1 H s) 7.25–7.35 (15 H m) and 7.50 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 26.3 (q) 61.6 (d) 121.6 (d) 127.3 (d) 128.0 (d) 128.2 (d) 128.6 (d) 130.2 (d) 134.1 (s) 138.4 (s) 144.0 (d) 169.9 (s) and 173.0 (s); vmax(neat)/cm21 1684 1622 1378 1334 1244 1172 784 760 and 700 [Found MH+ (FAB) 356.1652.C24H22NO2 (MH+) requires 356.1650]. General procedure for the preparation of the cinnamamides 5 To a solution of cinnamic acid (1 mmol) in 5 ml of acetonitrile was added triethylamine (1 equiv.) at room temperature. To a solution of carbodiimide (1.2 equiv.) in acetonitrile (10 ml) was added dropwise the resulting solution. After complete addition the mixture was further stirred at room temperature for 24 h after which it was acidified with 1 M hydrochloric acid (50 ml) and extracted with diethyl ether (3 × 20 ml).The combined extracts were dried (MgSO4) and concentrated in vacuo. The products were separated by column chromatography on silica gel and further purification by HPLC gave the cinnamamides. N-Benzyl-N-(benzylaminocarbonyl)cinnamamide 5a. Colourless crystals (76%); mp 111–112 8C (Found C 77.6; H 6.0; N 7.5. C24H22N2O2 requires C 77.8; H 6.0; N 7.6%); dH(270 MHz; CDCl3) 4.60 (2 H d JN9H,N9-a 5.5) 5.20 (2 H s) 6.80 (1 H d J2,3 15.5) 7.25–7.40 (16 H m) and 7.70 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 44.7 (t) 47.6 (t) 118.7 (d) 126.1 (d) 127.3 (d) 127.4 (d) 127.5 (d) 128.1 (d) 128.6 (d) 128.9 (d) 130.5 (d) 134.3 (s) 137.8 (s) 138.3 (s) 145.9 (d) 155.4 (s) and 170.2 (s); vmax(KBr)/cm21 1640 1535 1355 1185 and 705. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]cinnamamide 5b. Colourless oil (91%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.75 (3 H d JN-a,N-b 7.0) 5.07 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.60 (1 H d J2,3 16.0) 7.20–7.40 (15 H m) 7.60 (1 H d J2,3 16.0) and 9.00 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 22.6 (q) 50.8 (d) 51.4 (d) 120.3 (d) 126.0 (d) 126.3 (d) 127.1 (d) 127.2 (d) 128.0 (d) 128.5 (d) 128.6 (d) 128.7 (d) 130.1 (d) 134.5 (s) 141.8 (s) 143.2 (s) 144.0 (d) 154.6 (s) and 169.3 (s); vmax(neat)/cm21 1710 1656 1610 1522 1498 1376 786 762 and 700 [Found MH+ (FAB) 399.2073.C26H27N2O2 (MH+) requires 399.2072]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- methoxycinnamamide 5c. Colourless oil (75%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.75 (3 H d JN-a,N-b 7.0) 3.80 (3 H s) 5.10 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.45 (1 H d J2,3 15.0) 6.80 (2 H d J29,39 9.0) 7.20 (2 H d J29,39 9.0) 7.20–7.40 (10 H m) 7.60 (1 H d J2,3 15.0) and 9.15 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 22.6 (q) 50.7 (d) 51.4 (d) 55.3 (q) 114.2 (d) 117.8 (d) 126.0 (d) 127.0 (d) 127.1 (d) 127.3 (d) 128.3 (d) 128.6 (d) 128.7 (d) 130.0 (d) 142.0 (s) 143.4 (s) 143.8 (s) 154.8 (d) 161.3 (s) and 169.7 (s); vmax(neat)/cm21 1708 1650 1598 1576 1512 1452 782 762 and 700 [Found MH+ (FAB) 433.1674.C27H29N2O3 (MH+) requires 433.1683]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- methylcinnamamide 5d. Colourless oil (72%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.80 (3 H d JN-a,N-b 7.0) 2.30 (3 H s) 5.10 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.55 (1 H d J2,3 15.0) 7.10–7.40 (14 H m) 7.60 (1 H d J2,3 15.0) and 9.05 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 21.3 (q) 22.6 (q) 50.7 (d) 51.4 (d) 119.2 (d) 126.0 (d) 127.06 (d) 127.12 (d) 128.0 (d) 128.6 (d) 128.7 (d) 129.5 (d) 131.8 (d) 140.6 (s) 141.9 (s) 143.3 (s) 144.0 (d) 154.7 (s) and 169.6 (s); vmax(neat)/cm21 1704 1650 1602 1514 1498 1368 812 786 760 and 700 [Found MH+ (FAB) 413.2233.C27H29N2O2 (MH+) requires 413.2229]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- chlorocinnamamide 5e. Colourless oil (86%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.5) 1.75 (3 H d JN-a,N-b 7.5) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.30 (1 H q JN-a,N-b 7.5) 6.55 (1 H d J2,3 15.5) 7.10–7.40 (14 H m) 7.50 (1 H d J2,3 15.5) and 8.80 (1 H br); dC(22.4 MHz; CDCl3) 18.3 (q) 22.1 (q) 50.6 (d) 51.6 (d) 120.3 (d) 125.7 (d) 125.96 (d) 126.02 (d) 127.1 (d) 128.1 (d) 128.5 (d) 128.8 (d) 128.9 (d) 132.7 (s) 135.7 (s) 141.7 (s) 142.1 (d) 142.9 (s) 154.1 (s) and 168.1 (s); vmax(neat)/cm21 1702 1656 1610 1530 1494 1372 1262 1094 786 762 and 700 [Found MH+ (FAB) 399.2073.C26H26N2O2Cl (MH+) requires 399.2072]. General procedure for the photocycloaddition of the cinnamamides 2 A solution containing cinnamamide (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated with 82 J. Chem. Soc. Perkin Trans. 1 1997 a high-pressure mercury lamp under an Ar atmosphere at room temperature the reaction being monitored by HPLC and a UV detector. After irradiation the mixture was evaporated in vacuo. The products were separated by column chromatography on silica gel (ethyl acetate–hexane) and purified by HPLC (ethyl acetate–hexane) to give the photocycloadducts.(5S*,6R*)-N-Benzyl-6-phenyl-3-azatricyclo[5.2.2.01,5]undeca- 8,10-diene-2,4-dione 2a. Colourless oil (93%); dH(270 MHz; CDCl3) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 1.0 and J5,6 7.0) 3.90 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 5.5 and J7,10 6.0) 4.65 (2 H s) 6.05 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 42.2 (t) 44.9 (d) 45.1 (d) 55.8 (s) 57.6 (d) 126.8 (d) 127.1 (d) 127.8 (d) 128.5 (d) 128.6 (d) 132.2 (d) 132.5 (d) 133.8 (d) 136.1 (s) 141.8 (d) 142.6 (s) 175.0 (s) and 176.0 (s); vmax(neat)/cm21 1712 1384 1344 1131 794 758 and 700 [Found MH+ (FAB) 342.1478.C23H20NO2 (MH+) requires 342.1494]. (5S*,6R*)-N-Benzyl-7-methyl-6-phenyl-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2c. Colourless oil (>95%); dH(90 MHz; C6D6) 1.00 (3 H s) 2.65 (1 H d J5,6 7.5) 2.95 (1 H d J5,6 7.5) 4.70 (2 H d J 2.0) 5.80 (1 H d J8,9 7.5) 6.00 (1 H d J10,11 7.1) 6.20 (1 H d J10,11 7.0) 6.90 (1 H d J8,9 7.5) and 6.97–7.31 (10 H m); the 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product. (1R*,5S*,6R*,7S*)-N-Benzyl-10-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a major product of 2d). Colourless oil (47%); dH(270 MHz; CDCl3) 1.90 (3 H d J10-Me,11 2.0) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 1.5 and J5,6 7.0) 3.60 (1 H dddd J6,7 1.5 J7,9 1.5 J7,11 2.0 and J7,8 5.5) 4.65 (2 H d J2,5 2.5) 5.65 (1 H dd J7,11 2.0 and J10-Me,11 2.0) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 7.05 (1 H dd J7,9 1.5 and J8,9 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 18.5 (q) 42.2 (t) 44.6 (d) 50.6 (d) 56.3 (s) 58.9 (d) 125.1 (d) 126.8 (d) 127.1 (d) 127.8 (d) 128.6 (d) 128.7 (d) 132.1 (d) 134.3 (d) 136.2 (s) 142.9 (s) 152.1 (s) 175.4 (s) and 176.2 (s); vmax(neat)/cm21 1716 1386 1344 790 750 and 700 [Found MH+ (FAB) 356.1656.C24H22NO2 (MH+) requires 356.1651]. (1S*,5S*,6R*,7R*)-N-Benzyl-8-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a minor product of 2d). Colourless oil (36%); dH(270 MHz; CDCl3) 1.80 (3 H d J8-Me,9 2.0) 3.00 (1 H d J5,6 7.0) 3.15 (1 H dd J6,7 1.5 and J5,6 7.0) 3.50 (1 H dddd J6,7 1.5 J7,11 1.5 J7,9 2.0 and J7,10 5.5) 4.65 (s 2 H) 6.05 (1 H dd J7,11 1.5 and J10,11 7.5) 6.65 (1 H dd J7,9 2.0 and J8-Me,9 2.0) 6.90 (1 H dd J7,10 5.5 and J10,11 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 21.6 (q) 42.1 (t) 44.7 (d) 51.7 (d) 51.7 (d) 55.6 (s) 57.6 (d) 126.2 (d) 127.0 (d) 127.1 (d) 127.8 (d) 128.6 (d × 2) 133.0 (d) 136.2 (s) 141.5 (d) 142.1 (s) 142.7 (s) 175.0 (s) and 176.3 (s); vmax(neat)/cm21 1722 1386 1342 782 756 and 700 [Found MH+ (FAB) 356.1652.C24H22NO2 (MH+) requires 356.1651]. (1R*,5S*,6R*,7S*)-N-Benzyl-11-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a minor product of 2e). Colourless oil (13%); dH(270 MHz; CDCl3) 1.45 (3 H d J11-Me,10 2.0) 2.75 (1 H d J5,6 7.5) 3.25 (1 H dd J6,7 1.5 and J5,6 7.5) 3.80 (1 H dddd J6,7 1.5 J 7,9 1.5 J7,8 5.0 and J 7,10 6.5) 4.65 (2 H s) 6.40 (1 H dd J11-Me,10 2.0 and J7,10 6.5) 6.45 (1 H dd J7,8 5.0 and J8,9 7.0) 7.05 (1 H dd J7,9 1.5 and J8,9 7.0) 7.15– 7.35 (8 H m) and 7.45 (2 H dd J 2.0 and 7.5); dC(22.4 MHz; CDCl3) 16.9 (q) 42.2 (t) 45.0 (d) 45.2 (d) 58.1 (d) 59.0 (s) 126.8 (d) 127.1 (d) 128.0 (d) 128.6 (d) 129.4 (d) 133.3 (d) 134.1 (d) 134.6 (d) 136.0 (s) 140.3 (s) 142.9 (s) 174.6 (s) and 175.5 (s); vmax(neat)/cm21 1714 1384 1342 1070 788 756 728 and 700 [MH+ (FAB) 356.1649.C24H22NO2 (MH+) requires 356.1650]. (1R*,5S*,6R*,7R*)-N-Benzyl-9-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a major product of 2e). Colourless oil (22%); dH(270 MHz; CDCl3) 2.10 (3 H d J9-Me,8 1.5) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 2.0 and J5,6 7.0) 3.75 (1 H dddd J6,7 2.0 J7,11 2.0 J7,8 5.5 and J7,10 6.5) 4.65 (2 H s) 5.95 (1 H dd J9-Me,8 1.5 and J7,8 5.5) 6.00 (1 H dd J7,11 2.0 and J10,11 7.0) 6.90 (1 H dd J7,10 6.5 and J10,11 7.0) and 7.15– 7.40 (10 H m); dC(22.4 MHz; CDCl3) 16.1 (q) 42.1 (t) 44.8 (d) 45.4 (d) 57.1 (d) 57.5 (s) 125.5 (d) 126.7 (d) 127.2 (d) 127.8 (d) 128.6 (d) 128.7 (d) 131.8 (d) 136.2 (s) 142.6 (d) 142.9 (s) 144.8 (s) 175.3 (s) and 175.8 (s); vmax(neat)/cm21 1718 1432 1384 1348 1072 788 756 and 700 [Found MH+ (FAB) 356.1658.C24H22NO2 (MH+) requires 356.1651]. (5S*,6R*)-N-Benzyl-7-chloro-6-phenyl-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2f. Colourless oil (71%); dH(270 MHz; CDCl3) 3.00 (1 H d J5,6 7.0) 3.40 (1 H d J5,6 7.0) 4.65 (2 H s) 6.10 (1 H d J10,11 7.0) 6.45 (1 H d J8,9 8.5) 6.90 (1 H d J10,11 7.0) 7.05 (1 H d J8,9 8.5) and 7.20–7.35 (10 H m); the 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product.(5S*,6R*)-6-Phenyl-N-(1-phenylethyl)-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2h. (99%) Diastereoisomer A.— Colourless oil; dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.5) 2.70 (1 H d J5,6 7.5) 3.20 (1 H dd J6,7 1.5 and J5,6 7.5) 3.90 (1 H ddddd J7,9 1.0 J7,11 1.0 J6,7 1.5 J7,8 5.5 and J7,10 6.0) 5.40 (1 H q JN-a,N-b 7.5) 6.00 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.00 (1 H dd J7,9 1.0 and J8,9 7.5) 7.10–7.40 (8 H m) and 7.45 (2 H dd J 1.0 and 7.0); dC(22.4 MHz; CDCl3) 16.9 (q) 45.1 (d) 45.2 (d) 49.8 (d) 55.7 (s) 57.5 (d) 126.9 (d) 127.2 (d) 127.4 (d) 127.7 (d) 128.4 (d) 128.7 (d) 132.0 (d) 132.6 (d) 133.8 (d) 139.5 (s) 141.9 (d) 142.7 (s) 175.2 (s) and 176.1 (s); vmax(neat)/cm21 3060 3028 2972 1776 1710 1500 1374 1346 758 and 698.Diastereoisomer B.—Colourless oil; dH(270 MHz; CDCl3) 1.80 (3 H d JN-a,N-b 7.5) 2.75 (1 H d J5,6 7.5) 3.20 (1 H dd J6,7 1.5 and J5,6 7.5) 3.90 (1 H ddddd J7,9 1.0 J7,11 1.0 J6,7 1.5 J7,8 5.5 and J7,10 6.0) 5.45 (1 H q JN-a,N-b 7.5) 6.10 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) 7.10– 7.40 (8 H m) and 7.45 (2 H dd J 1.0 and 7.0); dC(22.4 MHz; CDCl3) 16.6 (q) 45.0 (d) 45.1 (d) 50.1 (d) 55.7 (s) 57.6 (d) 126.9 (d) 127.2 (d × 2) 127.7 (d) 128.5 (d) 128.7 (d) 132.1 (d) 132.6 (d) 133.9 (d) 140.2 (s) 142.0 (d) 142.7 (s) 175.1 (s) and 176.1 (s); vmax(neat)/cm21 1715 1500 1460 1378 1342 1154 1050 1030 782 758 and 698 [Found MH+ (FAB) 356.1654.C24H22NO2 (MH+) requires 356.1651]. A mixture of diastereoisomers of (5S*,6R*)-7,8,9,10,11- pentadeuterio-6-phenyl-N-(1-phenylethyl)-3-azatricyclo- [5.2.2.01,5]undeca-8,10-diene-2,4-dione 2h9. Colourless oil (99%); dH(270 MHz; CDCl3) 1.80 (1.5 H d JN-a,N-b 7.5) 1.85 (1.5 H d JN-a,N-b 7.5) 2.70 (0.5 H d J5,6 7.5) 2.75 (0.5 H d J5,6 7.5) 3.15 (0.5 H dd J5,6 7.5) 3.20 (0.5 H d J5,6 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 7.15–7.40 (8 H m) and 7.45 (2 H dd and J 1.0 7.0) [Found MH+ (FAB) 361.1970. C24H17D5NO2 (MH+) requires 361.1964]. A mixture of diastereoisomers of (5S*,6R*)-7-methyl-6- phenyl-N-(1-phenylethyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10- diene-2,4-dione 2j.Colourless oil ( >99%); dH(270 MHz; C6D6) 1.20 (1.5 H s) 1.20 (1.5 H s) 2.05 (1.5 H d JN-a,N-b 7.0) 2.10 (1.5 H d JN-a,N-b 7.0) 2.95 (0.5 H d J5,6 7.0) 3.00 (0.5 H d J5,6 7.0) 3.20 (0.5 H d J5,6 7.0) 3.25 (0.5 H d J5,6 7.0) 5.85 (0.5 H q JN-a,N-b 7.0) 5.85 (0.5 H q JN-a,N-b 7.0) 6.00 (1 H d J10,11 7.0) 6.25 (0.5 H d J10,11 7.0) 6.35 (0.5 H d J10,11 7.0) 6.45 (0.5 H d J10,11 7.0) 6.45 (0.5 H d J10,11 7.0) 7.10 (0.5 H d J8,9 7.5) 7.15 (0.5 H d J8,9 7.5) and 7.25–7.60 (10 H m). The 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product. A mixture of diastereoisomers of (5S*,6R*)-7-chloro-6-phenyl- N-(1-phenylethyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2k. Colourless oil (92%); dH(270 MHz; CDCl3) 1.80 (1.5 H d JN-a,N-b 7.5) 1.80 (1.5 H d JN-a,N-b 7.5) 2.95 (0.5 H d J5,6 7.0) 2.95 (0.5 H d J5,6 7.0) 3.35 (0.5 H d J5,6 7.0) 3.40 (0.5 H, J.Chem. Soc. Perkin Trans. 1 1997 83 d J5,6 7.0) 5.35 (0.5 H q JN-a,N-b 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 6.00 (0.5 H d J10,11 7.0) 6.10 (0.5 H d J10,11 7.0) 6.40 (0.5 H d J8,9 7.5) 6.45 (0.5 H d J8,9 7.5) 6.85 (1 H d J10,11 7.0) 7.00 (0.5 H d J 7.5) 7.05 (0.5 H d J10,11 7.5) and 7.20–7.40 (10 H m); vmax(neat)/cm21 1718 1658 1620 1378 1340 760 and 700. The 13C NMR and HRMS spectra were not measured because of the unstable nature of the product. A mixture of diastereoisomers of (5S*,6R*)-6-phenyl-N-(1- phenylpropyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2n. Colourless oil (87%); dH(270 MHz; CDCl3) 0.95 (1.5 H t JN-b,N-g 7.5) 0.95 (1.5 H t JN-b,N-g 7.5) 2.20 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.25 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.45 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.55 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.65 (0.5 H d J5,6 7.0) 2.70 (0.5 H d J5,6 7.0) 3.20 (1 H dd J6,7 and J5,6 7.0) 3.85–3.90 (1 H m) 5.10 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 6.00 (0.5 H dd J7,11 1.0 and J10,11 7.0) 6.10 (0.5 H dd J7,11 1.0 and J10,11 7.0) 6.45 (0.5 H dd J7,8 5.5 and J8,9 7.5) 6.45 (0.5 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 7.0 and J10,11 7.0) 7.00 (0.5 H dd J7,9 1.5 and J8,9 7.5) 7.05 (0.5 H dd J7,9 1.5 and J8,9 7.5) 7.18–7.37 (8 H m) and 7.45 (2 H d J 7.5); vmax(neat)/ cm21 1714 1380 1346 788 758 and 700 [Found MH+ (FAB) 370.1800.C25H24NO2 (MH+) requires 370.1807]. A mixture of diastereoisomers of (5S*,6R*)-7,8,9,10,11-pentadeuterio- 6-phenyl-N-(1-phenylpropyl)-3-azatricyclo[5.2.2.01,5]undeca- 8,10-diene-2,4-dione 2n9. Colourless oil (79%); dH(270 MHz; CDCl3) 0.95 (1.5 H t JN-b,N-g 7.5) 0.95 (1.5 H t JN-b,N-g 7.5) 2.20 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.25 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.45 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.55 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.65 (0.5 H d J5,6 7.0) 2.70 (0.5 H d J5,6 7.0) 3.20 (1 H d J5,6 7.0) 5.10 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 7.20–7.35 (8 H m) and 7.45 (2 H d J 7.5) [Found MH+ (FAB) 375.2122. C25H19D5NO2 (MH+) requires 375.2121]. (5S*,6R*)-6-Phenyl-N-(diphenylmethyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4-dione 2o. Colourless oil (98%); dH(270 MHz; CDCl3) 2.80 (1 H d J5,6 7.0) 3.25 (1 H dd J6,7 1.5 and J5,6 7.0) 3.90 (1 H ddddd J7,9 1.0 J6,7 1.5 J7,11 1.5 J7,8 6.0 and J7,10 6.5) 6.10 (1 H dd J7,11 1.5 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.55 (1 H s) 6.95 (1 H dd J7,10 6.5 and J10,11 7.0) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.15–7.40 (15 H m); dC(22.4 MHz; CDCl3) 45.1 (d) 45.2 (d) 55.8 (s) 57.7 (d) 58.1 (d) 126.9 (d) 127.2 (d) 127.7 (d) 127.8 (d) 128.4 (d) 128.5 (d) 128.7 (d) 131.9 (d) 132.7 (d) 133.8 (d) 137.7 (s) 138.0 (s) 142.1 (d) 142.6 (s) 174.9 (s) and 175.7 (s); vmax(neat)/cm21 1718 1662 1498 1378 1346 786 738 and 700 [Found MH+ (FAB) 418.1807. C29H24NO2 (MH+) requires 418.1807].(5S*,6R*)-7,8,9,10,11-Pentadeuterio-6-phenyl-N-(diphenylmethyl)- 3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4-dione 2o9. Colourless oil (99%); dH(270 MHz; CDCl3) 2.80 (1 H d J5,6 7.0) 3.25 (1 H d J5,6 7.0) 6.55 (1 H s) and 7.15–7.40 (15 H m) [Found MH+ (FAB) 423.2122. C29H19D5NO2 (MH+) requires 423.2121]. (5S*,6R*)-N-(1-Methyl-1-phenylethyl)-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione 2p. Colourless oil (84%); dH(270 MHz; CDCl3) 1.90 (3 H s) 1.95 (3 H s) 2.70 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 0.5 and J5,6 7.0) 3.85 (1 H ddddd J6,7 0.5 J7,9 1.0 J7,11 1.0 J7,8 5.5 and J7,10 6.5) 6.20 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.95 (1 H dd J7,10 6.5 and J10,11 7.0) 7.00 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.20–7.35 (10 H m); dC(22.4 MHz; CDCl3) 28.4 (q) 28.9 (q) 45.1 (d) 45.2 (d) 55.8 (s) 58.0 (d) 61.8 (s) 124.3 (d) 126.8 (d) 127.2 (d) 128.3 (d) 128.6 (d) 131.9 (d) 132.6 (d) 134.1 (d) 142.0 (d) 142.8 (s) 146.3 (s) 175.9 (s) and 176.7 (s); vmax(neat)/cm21 1780 1724 1368 1328 1220 1060 784 756 and 700 [Found MH+ (FAB) 370.1809.C25H24NO2 (MH+) requires 370.1807]. (5S*,6R*)-7,8,9,10,11-Pentadeuterio-N-(1-methyl-1-phenylethyl)- 6-phenyl-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2p9. Colourless oil (99%); dH(270 MHz; CDCl3) 1.90 (3 H s) 1.95 (3 H s) 2.70 (1 H d J5,6 7.0) 3.20 (1 H d J5,6 7.0) and 7.20–7.35 (10 H m) [Found MH+ (FAB) 375.2117. C25H19D5NO2 (MH+) requires 375.2121]. (2S*,5S*,6R*)-N-Acetyl-2,6-diphenyl-3-azatricyclo[5.2.2.01,5]- undeca-8,10-dien-4-one 4b. Colourless oil (42%); dH(270 MHz; CDCl3) 2.55 (3 H s) 2.80 (1 H d J5,6 6.0) 3.20 (1 H dd J6,7 1.5 and J5,6 6.0) 3.80–3.85 (1 H m) 5.85 (1 H s) 6.25–6.30 (3 H m) 6.85 (1 H dd J7,10 6.5 and J10,11 7.5) and 7.15–7.45 (10 H m); dC(22.4 MHz; CDCl3) 25.2 (q) 45.3 (d) 46.5 (d) 51.7 (s) 56.5 (d) 64.5 (d) 126.2 (d) 126.6 (d) 127.3 (d) 128.0 (d) 128.5 (d) 129.0 (d) 132.7 (d) 134.7 (d) 136.0 (d) 141.6 (d) 143.3 (s) 170.7 (s) and 175.0 (s); vmax(neat)/cm21 2972 2924 1744 1690 1374 1334 1280 and 666 [Found MH+ (FAB) 356.1638.C24H22NO2 (MH+) requires 356.1650]. (2S*,5S*,6R*)-2-Methyl-6-phenyl-N-[(1-phenylethyl)aminocarbonyl]- 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4-one 6b. Colourless oil (56%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 7.0) 1.50 (3 H d JN9-a,N9-b 7.5) 2.75 (1 H d J5,6 6.5) 3.15 (1 H dd J6,7 2.0 and J5,6 6.5) 3.90 (1 H ddddd J7,9 0.5 J7,11 0.5 J6,7 2.0 J7,8 5.5 and J7,10 6.5) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 0.5 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.70 (1 H dd J7,9 0.5 and J8,9 7.5) 6.80 (1 H dd J7,10 6.5 and J10,11 7.5) 7.15–7.35 (10 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 44.9 (d) 46.0 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.5 (d) 125.9 (d) 126.6 (d) 127.2 (d × 2) 128.6 (d × 2) 133.6 (d) 134.5 (d) 136.2 (d) 141.3 (d) 143.5 (s) 152.1 (s) and 176.3 (s); vmax(neat)/cm21 1714 1534 1370 1342 1232 760 718 and 700 [Found MH+ (FAB) 399.2077.C26H27N2O2 (MH+) requires 399.2072]. (2S*,5S*,6R*)-2-Methyl-6-(4-methoxyphenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6c.Colourless oil (55%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 7.0 Hz) 1.50 (3 H d JN9-a,N9-b 7.3) 2.70 (1 H d J5,6 6.5 Hz) 3.13 (1 H dd J6,7 1.5 and J5,6 6.5) 3.75 (3 H s) 3.85 (1 H ddddd J6,7 1.5 J7,9 1.5 J7,11 1.5 J7,8 6.0 and J7,10 6.0) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 1.5 and J10,11 7.5) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.5 and J8,9 7.5) 6.80 (2 H d J29,39 9.0) 6.80 (1 H dd J7,10 6.0 and J10,11 7.5) 7.15 (2 H d J29,39 9.0) 7.15–7.35 (5 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 45.2 (d) 49.7 (d) 51.3 (d) 55.3 (s) 57.4 (d) 57.5 (d) 114.0 (d) 125.9 (d) 127.2 (d) 128.2 (d) 128.6 (d) 133.6 (d) 134.5 (d) 135.7 (d) 136.0 (d) 141.3 (s) 143.6 (s) 152.2 (s) 158.3 (s) and 176.4 (s); vmax(neat)/cm21 1715 1520 1375 1250 1180 765 and 705 [Found MH+ (FAB) 429.2161.C27H29N2O3 (MH+) requires 429.2178]. (2S*,5S*,6R*)-2-Methyl-6-(4-methylphenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6d. Colourless oil (56%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 6.5) 1.50 (3 H d JN9-a,N9-b 7.0) 2.30 (3 H s) 2.70 (1 H d J5,6 6.5) 3.10 (1 H dd J6,7 1.0 and J5,6 6.5) 3.85 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 6.0 and J7,10 6.5) 4.85 (1 H q J2,2-Me 6.5) 5.05 (1 H dq JN9H,N9-a 7.0 and JN9-a,N9-b 7.0) 6.15 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.0 and J8,9 7.5) 6.80 (1 H dd J7,10 6.5 and J10,11 7.0) 7.10 (2 H d J29,39 8.5) 7.15 (2 H d J29,39 8.5) 7.15–7.35 (5 H m) and 8.70 (1 H d JN9H,N9-a 7.0); dC(22.4 MHz; CDCl3) 14.7 (q) 20.9 (q) 22.9 (q) 45.0 (d) 45.6 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.4 (d) 125.9 (d) 127.1 (d) 128.6 (d) 129.2 (d) 133.7 (d) 134.4 (d) 136.1 (d) 136.2 (s) 140.5 (s) 141.3 (d) 143.6 (s) 152.1 (s) and 176.4 (s); vmax(neat)/cm21 2972 1716 1690 1532 1372 1344 1232 and 762 [Found MH+ (FAB) 413.2222.C27H29N2O2 (MH+) requires 413.2229]. (2S*,5S*,6R*)-2-Methyl-6-(4-chlorophenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6e. Colourless oil (61%); dH(270 MHz; CDCl3) 1.50 (3 H, 84 J. Chem. Soc. Perkin Trans. 1 1997 d J2,2-Me 7.0) 1.50 (3 H d JN9-a,N9-b 7.5) 2.65 (1 H d J5,6 6.0) 3.10 (1 H dd J6,7 1.0 and J5,6 6.0) 3.85 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 6.0 and J7,10 6.0) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.0 and J8,9 7.5) 6.80 (1 H dd J7,10 6.0 and J10,11 7.0) 7.15– 7.40 (9 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 44.7 (d) 45.4 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.5 (d) 125.9 (d) 127.2 (d) 128.6 (d) 128.6 (d) 132.4 (s) 133.3 (d) 134.9 (d) 136.3 (d) 141.1 (d) 142.0 (s) 143.4 (s) 152.0 (s) and 176.0 (s); vmax(neat)/cm21 1714 1530 1496 1372 790 762 700 and 666 [Found MH+ (FAB) 433.1674.C26H26N2O2Cl (MH+) requires 433.1683]. References 1 (a) J. Cornelisse Chem. Rev. 1993 93 615; (b) P. A. Wender L. Shiggel and J. M. Nuss Org. Photochem. 1989 10 357; (c) P. J. Wagner Acc. Chem. Res. 1989 22 83; (d ) H. Aoyama Y. Arata and Y. Omote J. Chem.Soc. Chem. Commun. 1990 736; (e) N. Al-Jalel and A. Gilbert Recl. Trav. Chim. Pays-Bas 1990 109 21; (f ) P. A. Wender and M. A. deLong Tetrahedron Lett. 1990 31 5429; (g) A. Gilbert and P. W. Rodwell J. Chem. Soc. Perkin Trans. 1 1990 932; (h) D. Bryce-Smith and A. Gilbert Tetrahedron 1977 33 2459; (i) D. Bryce-Smith A. Gilbert B. H. Orger and H. M. Tyrrell J. Chem. Soc. Chem. Commun. 1974 334; (j) D. Bryce-Smith B. Foulger J. Forrester A. Gilbert B. H. Orger and H. M. Tyrrell J. Chem. Soc. Perkin Trans. 1 1980 55; (k) A. Gilbert G. N. Taylor and M. W. bin Samsudin J. Chem. Soc. Perkin Trans. 1 1980 869; (l) J. Mattay H. Leismann and H. D. Scharf Chem. Ber. 1979 112 577; (m) H. G. Heine and W. Hartmann Angew. Chem. Int. Ed. Engl. 1975 14 698; (n) M. F. Mirbach M. J. Mirbach and A.Saus Tetrahedron Lett. 1977 959. 2 D. Bryce-Smith B. Foulger J. Forrester and A. Gilbert J. Chem. © Copyright 1997 by the Royal Society of Chemistry Soc. Chem. Commun. 1972 664; J. C. Berridge J. Forrester B. Foulger and A. Gilbert J. Chem. Soc. Perkin Trans. 1 1980 2425. 3 A. Gilbert and P. W. Rodwell J. Chem. Soc. Perkin Trans. 1 1990 931. 4 H. D. Scharf H. Leismann W. Erb and J. Aretz Pure Appl. Chem. 1975 41 581. 5 G. O. Schenck J. Kuhls and C. H. Krauch Justus Liebigs Ann. Chem. 1966 693 20; K. Kraft G. Koltzenburg and G. O. Schenck Tetrahedron Lett. 1965 353; T. S. Cantrell J. Org. Chem. 1974 39 3063. 6 The MM2 force field in Chem3D (Cambridge Soft Co.) was used for the calculation. Cf. U. Bunkert and N. L. Allinger Molecular Mechanics ACS Washington DC USA 1982; J. W. Ponder J.Comput. Chem. in preparation. 7 D. Bryce-Smith and A. Gilvert Tetrahedron 1976 32 1309. 8 G. Himbert K. Kiehl and G. Maas J. Chem. Soc. Chem. Commun. 1984 900; L. A. M. Turkenburg P. M. L. Blok W. H. De Wolf and F. Bickelhaupt Angew. Chem. Int. Ed. Engl. 1982 21 298; A. F. Murad J. Kleinschroth and H. Hopf Angew. Chem. Int. Ed. Engl. 1980 19 389. 9 M. Wollenweber H. Fritz G. Rihs and H. Prinzbach Chem. Ber. 1991 124 2465; M. Mintas D. I. Schuster and P. G. Willard Tetrahedron 1988 44 6001. 10 J. Bregmen K. Osaki G. M. J. Schmidt and F. I. Sontag J. Chem. Soc. 1964 2021. 11 W. M. Hardham and G. S. Hammond J. Am. Chem. Soc. 1967 89 3200. 12 S. Kohmoto T. Kreher Y. Miyaji M. Yamamoto and K. Yamada J. Org. Chem. 1992 57 3490. 13 J. S. Bradshaw J. Org. Chem. 1966 31 3974. 14 T. S.Lee S. J. Lee and S. C. Shim J. Org. Chem. 1990 55 4544. Paper 6/01710J Received 11th March 1996 Accepted 19th August 1996 J. Chem. Soc. Perkin Trans. 1 1997 77 Intramolecular photo[4+2]cycloaddition of an enone with a benzene ring Keiki Kishikawa,* Satoshi Akimoto Shigeo Kohmoto Makoto Yamamoto and Kazutoshi Yamada Department of Materials Science Faculty of Engineering Chiba University 1-33 Yayoi-cho Inage-ku Chiba 263 Japan N-Benzoyl-N-benzylcinnamamides 1 N-acetyl-N-(1-benzyl)cinnamamides 3 and N-[(1-benzyl)- aminocarbonyl]-N-(1-benzyl)cinnamamides 5 have been irradiated by a high-pressure mercury lamp in the presence of benzil in benzene at room temperature to give 3-azatricyclo[5.2.2.01,5]undeca-8,10- dien-4-ones 2 4 and 6 with high stereoselectivity. These are the first photo[4+2]cycloadducts of an enone and a benzene ring.Photo-[2+2]- and -[3+2]-cycloadditions of alkenes to benzenes are typical reactions of the latter and many examples have been reported.1 In contrast photo[4+2]cycloaddition of benzene is much rarer the only known examples being photocycloaddition with dienes,2 furan3 and dichlorovinylene carbonate;4 such reactions showed low selectivity and gave poor product yields. Similarly photo[4+2]cycloadditions of enones are rare compared with the numerous examples of [2+2]cycloadditions with dienes; the only known examples of the former are the cycloadditions of enones with cyclopentadiene and furan;5 however both [4+2]- and [2+2]-addition showed poor selectivity. In order to achieve the hitherto unknown photo[4+2]cycloaddition of an enone with a benzene ring we designed intramolecular photo[4+2]cycloadditions of the cinnamamides 1 3 and 5.According to MM2 calculation,6 the [4+2]adduct 2a is 6.6 kcal mol21 more stable than the [2+2]adduct 2a9 and 102.8 kcal mol21 more stable than the [3+2]adduct 2a0. In these reactions the [4+2]adducts 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4- ones 2 4 and 6 were obtained as the sole products with perfect regio- and stereo-selectivity. The photo[4+2]cycloaddition of a benzene ring and an enone is novel although the [4+2] process is symmetry allowed from (i) the excited ethene (S1 or T1) with the S0 benzene or from (ii) the triplet excited benzene with S0 ethene.1h,7 Even thermal [4+2]cycloaddition of an enone to a benzene ring is very limited highly strained benzenes being required to react with reactive dienophiles.8 An enone fixed rigidly and closely to a diene moiety was reported by Wollenweber to undergo an intramolecular diene/ enone photo[4+2]cycloaddition from the excited state in a stepwise radical reaction.9 Aoyama et al.also reported an intramolecular photo[2+2]cycloaddition of an alkene and a benzene ring connected with a CO]N bond.1d If the 2- and 3-carbons of an enone are close enough to the carbons at the 19- and 49- position of the benzene ring respectively a diradical generated from the excited enone must react with the carbons at the 19- and 49-positions to give a [4+2]adduct (Fig. 1). Based on this idea we planned to hold the enone double bond in an N O O Ph R N O O Ph R H H H 2a' 2a" P16/01710J/B1 appropriate position for [4+2]cycloaddition by linking it with a rigid and planar CO]N]CO bond to the benzene ring.To suppress polymerisation of the acryloyl group a phenyl group was introduced at its 3-position. The cinnamamides 1a–p were prepared by condensation of the corresponding acid chlorides and amines. The irradiation was carried out in benzene with a triplet sensitiser (benzil) using a high-pressure mercury lamp under an Ar atmosphere at room temperature. Cycloaddition of the cinnamoyl double bond to the benzoyl-benzene proceeded to give the [4+2]adducts 2 (Table 1). In the reaction of 1a (R1 = R2 = X = H) the cycloaddition was attempted with several sensitisers [anthracene (ET = 42 kcal mol21) benzil (ET = 53 kcal mol21) naphthalene (ET = 61 kcal mol21) benzophenone (ET = 69 kcal mol21) and acetophenone (ET = 74 kcal mol21)]; direct irradiation failed to induce any reaction.Benzil was found to be the only sensitiser for the photo[4+2]cycloaddition the others sensitising trans–cis isomerisation of the cinnamoyl function.10 The reason why benzil alone sensitised the reaction has yet to be clarified. However it is obvious that the reaction proceeds from a triplet excited state because of sensitisation by the triplet sensitiser (benzil). Photo[2+2]cycloaddition of maleic anhydride to benzene is known to be a triplet state reaction when the charge-transfer complex is sensitised by benzophenone the unsensitised process arising from the singlet state of the charge-transfer complex.7,11 In all cases perfect stereochemical control was achieved the stereochemistry being determined by NOE difference spectra (1H NMR spectroscopy).The selected data are shown in Scheme 1 and indicate the trans-configuration of the 5- and 6-protons. Although trans–cis isomerisation was observed by 1H NMR analysis during the irradiation the stereochemistry of the 5- and the 6-protons in the tricyclic products 2 was trans. The UV spectra of 1a and 2a were measured in acetonitrile at room temperature (Scheme 2). The peaks at 250–350 nm disappeared after the cycloaddition. Methoxy nitro and cyano substituents on the benzoyl function [1b 1i (X = MeO) 1g 1m (X = NO2) and 1l (X = CN)] resulted in complete suppression of the cycloaddition with recovery of Fig. 1 Mode of photo[4+2]cycloaddition N O O R N O O R h n 4' 3 1' 2 1 2' 3' 3 2 4' 1' 2' 3' 1 P16/01710J/A1 78 J. Chem. Soc. Perkin Trans.1 1997 starting material. In the reactions of 1 the cinnamoyl group reacted with the benzoyl group but not with benzyl. The electron density of the benzoyl group might control the reactivity. The stereoselectivity of the cyclisation is controlled by the steric repulsion between the phenyl and carbonyl in the cinnamoyl group. In the case of 1h 1n 1o and 1p the regioselectivity of the cycloaddition was deduced from the reaction of the deuteriated compounds the benzoyl group being replaced with [2H5]benzoyl (1h9 1n9 1o9 and 1p9) difficulties being experienced in determining the stereochemistry of the products by 1H NMR spectroscopy. In the 1H NMR spectra of the adducts (2h9 2n9 2o9 and 2p9) the signals for the protons at the bridgehead-carbons (C-7) and the double bond-carbons (C-8 Scheme 1 NOE spectra of photo products (selected data) N H H H H Ph H H O O Ph R1 R2 N H H H H Ph H H O Me O H Ph N H H H H Ph H H O N O H Me H Ph Me H 2h (R1=Me R2=H) 2a (R1=H R2=H) 2n (R1=Et R2=H) 2h (R1=Me R2=H) 2p (R1=Me R2=Me) 2o (R1=Ph R2=H) 2a (R1=H R2=H) 2n (R1=Et R2=H) 2o (R1=Ph R2=H) a b 2% 2p (R1=Me R2=Me) 4% 2% 3% 3% 2% 3% 2% 3% 6b 4b 7% 4% 2% 2% 12% 3% 1% 2% P16/01710J/B2 Table 1 Photo[4+2]cycloaddition of 1a–pa Ph O N O R1 R2 X N O O Ph H R1 R2 X 2a-p 1a-p hv /benzil in benzene at RT 1 2 3 4 5 6 7 8 9 10 11 P16/01710J/B5 Entry Starting material R1 R2 X Time (h) Product Yield (%)b 1 1a H H H 3 2a 93 2 1b p-MeO 16 2b 0 3 1c p-Me 2 2c 99c 4 1d m-Me 1 2d 83 5 1e o-Me 2 2e 35 6 1f p-Cl 6 2f 71 7 1g p-NO2 18 2g 0 8 1h Me H H 2 2h 99c 9 1i p-MeO 8 2i 0 10 1j p-Me 2 2j 99c 11 1k p-Cl 4 2k 92 12 1l p-CN 8 2l 0 13 1m p-NO2 8 2m 0 14 1n Et H 1 2n 87 15 1o Ph H 1 2o 98 16 1p Me Me H 1 2p 84 a A solution of 1 (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated by a high-pressure mercury lamp under Ar atmosphere at room temperature.b The yields are isolated yields. c The yield of products was determined by 1H NMR spectroscopy of the solution. The products were thermally unstable. C-9 C-10 and C-11) disappeared as a result of replacement. The results indicated that the benzoyl reacted with the cinnamoyl function. In order to investigate the reactivity of the benzyl group in the photocycloaddition the benzoyl group was changed to an acetyl group (Table 2). The reaction of N-acetyl-Nbenzylcinnamamide 3a (R = H) failed to give the [4+2]adduct 4a under similar reaction conditions.In contrast N-acetyl-N- (diphenylmethyl)cinnamamide 3b (R = Ph) produced the adduct 4b in low yield. The products were expected to be a mixture of diastereoisomers because of the three asymmetric centres. However the single diastereoisomer 4b was obtained and its structure was determined by NOE difference spectroscopy (Scheme 1). The a-substituent of the benzyl group might have some important role for the reactivity and the stereoselectivity. Irradiation of N-cinnamoyl-N,N9-bis(1-phenylethyl)- ureas 5b–e (R = Me) also gave single diastereoisomers (NOE of 6b is shown in Scheme 1) [4+2]adducts 6b–e; however Fig. 2 UV spectra of 1a and 2a. Concentration = 1.00 × 1025 M solvent = acetonitrile and temperature 20 8C. 200 250 300 350 l /nm 20000 e /dm3 mol –1 cm–1 15000 10000 5000 1a 2a P16/01710J/A2 Scheme 2 Mechanism for the intramolecular photo[4+2]cycloaddition Ph O N O R1 R2 N O O Ph H R1 R2 X X Ph O N O R1 R2 X N O O Ph H R1 R2 H X * C 2 1 hv /benzil 3 B 3 * Heat P16/01710J/B3 J.Chem. Soc. Perkin Trans. 1 1997 79 N-cinnamoyl-N,N9-dibenzylurea 5a (R = H) was inert under similar conditions of irradiation (Table 3). In our previous report type II photocyclisation was observed in the reaction of N-acryloyl-N,N9-bis(1-phenylethyl)ureas to give b-lactam derivatives. 12 Thus a 3-phenyl substituent on the acryloyl group completely suppressed the hydrogen abstraction ability of the enone double bond. These results indicate that the a-substituted benzyl group is also reactive with the cinnamoyl group. In the case of 3b and 5b–e it is clear that the cinnamoyl group was excited by the sensitiser (benzil) to generate the diradical which reacted with the benzyl group since the benzyl aromatic ring itself is not excited by benzil.As with these reactions for compound 1 it also seems that benzil sensitises the cinnamoyl group which reacts with the benzoyl. The mechanism for the photo[4+2]cycloaddition was postulated as follows (Scheme 2). The cinnamoyl group of 1 is excited by irradiation in the presence of benzil (a triplet sensitiser) to give the diradical B. The symmetry-allowed photo[2+2]cycloaddition of an excited maleic anhydride–benzene complex (the triplet state) takes place because the face of the maleic anhydride-double bond and that of benzene smoothly interact. However in the reaction of 1 3 and 5 the face-to-face interaction for charge transfer 7,13 is difficult because of the rigid junction and stepwise cyclisation occurs.The stepwise [2+2]cyclisation of 1 3 and 5 needs a larger energy than the [4+2]cyclisation (from the MM2 calculation). The radical at the 2-position (more reactive than that at the 3-position),14 reacts with C-19 of the benzene ring to generate the spiro intermediate C. The methoxybenzoyl group (X = MeO) is not reactive Table 2 Photo[4+2]cycloaddition of 3a,ba 4a-b 3a-b hv /benzil in benzene at RT Ph O N R Me N O R Ph H O O Me P16/01710J/B6 Entry Starting material R Time (h) Product Yield (%)b 1 3a H 3 4a 0 2 3b Ph 2 4b 42 a The same procedure in Table 1. b Isolated yields. Table 3 Photo[4+2]cycloaddition of cinnamoylureas 5a–e 6a-e Ar O N O N O O R Ar H R N H R N H R 5a-e Ar = 4-XC6H4 hv /benzil in benzene at RT P16/01710J/B7 Entry Starting material R X Time (h) Product Yield (%)b 1 5a H H 15 6a 0 2 5b Me H 4 6b 56 3 5c MeO 6 6c 55 4 5d Me 4 6d 56 5 5e Cl 4 6e 61 a A solution of 5 (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated by a high-pressure mercury lamp under an Ar atmosphere at room temperature.b The yields are isolated yields. because an electron-rich benzene ring is an unsuitable acceptor of radicals. Suppression of reactivity by the nitro- and cyanogroups (X = NO2 and CN) is explained in terms of the unreactivity of the diradical in the generated diradical C which is stabilised by the electron acceptor groups. In C the a-proton is located cis to the phenyl group because of steric repulsion.In the photoreaction of N-(a-substituted benzyl) cinnamamides 3b and 5b–e the intermediate E is more favoured than D because of the steric repulsion between the R and the benzyl group (Scheme 3). In the photoreaction of a vinylene carbonate and benzene (Scharf et al.4) the initially generated [2+2]adducts are gradually transformed to the corresponding [4+2]- adducts. Accordingly the [2+2]adducts may be produced from the intermediate C at an early stage. However from the result of MM2 calculation the [2+2]adducts are less stable than the [4+2]products and their formation was not detected by monitoring with 1H NMR spectroscopy (Fig. 3). The trans–cis isomerisation occurs followed by the [4+2]cycloaddition during the irradiation. Some of the cinnamamides showed the thermal retro- [4+2]addition at room temperature (i.e.2cÆ1c t1/2 = 3 h). The stereochemistry of the recovered cinnamamide 1c was the trans-form only. Reconstruction of the conjugated system must be the driving force for the retro reaction. The intramolecular cycloaddition of a benzene ring in cinnamamides gives only the [4+2]adducts and does not produce other by-products ([2+2]- and [3+2]-adducts). Now we are studying its utilisation for the photosensitive materials. Experimental General Mps were determined on a Yanako MP-S3 melting-point apparatus and are uncorrected. 1H NMR (270 400 500 MHz) and 13C NMR (22.4 67.8 MHz) spectra were recorded in CDCl3 or C6D6 and were referenced against internal tetramethylsilane. Chemical shifts are reported in ppm on the d scale. Coupling constants (J) are given in Hz.High-performance Fig. 3 Monitor of photo[4+2]cycloaddition of 2a. A solution of trans-1a (0.03 mmol) and benzil (0.03 mmol) in [2H6]benzene (1.0 ml) in a Pyrex tube was irradiated by a high-pressure mercury lamp (450 W) under an argon atmosphere. The percentages of trans-1a cis-1a and 2a were monitored by 1H NMR spectroscopy. 0 4 8 12 16 20 24 28 20 40 60 80 100 Yield (%) Irradiation time/(min) trans -1a cis -1a 2a P16/01710J/A3 Scheme 3 Diradical intermediates generated from 3b (R = Ph R9 = CH2Ph) and 5b [R = Me R9 = CONHCH(CH3)Ph] D (disfavoured) E (favoured) O N H Ph R R' O N H Ph R R' P16/01710J/B4 80 J. Chem. Soc. Perkin Trans. 1 1997 liquid chromatography (HPLC) was performed on Merck Lichrosorb Si 60 column (7 mm) eluting with ethyl acetate– hexane.Flash column chromatography (ethyl acetate–hexane) was performed with Fuji silica gel BW-200 (200 mesh). Photoreactions were carried out using a USHIO 450 W high-pressure mercury lamp. All solvents were freshly distilled and stored over 4 Å molecular sieves. N-Alkylcinnamamides and N-alkylbenzamides were prepared from the corresponding commercially available amines and acid chlorides. General procedure for the preparation of the cinnamamides 1 and 3 To a solution of N-alkylcinnamamide (1 mmol) in benzene (20 ml) was added triethylamine (1.2 equiv.) at room temperature. To the resulting solution was added dropwise the appropriate acyl chloride (1.2 equiv.). The resulting mixture was heated at reflux for 24 h after which it was quenched with saturated aqueous NaHCO3 (20 ml) and washed with 1 M hydrochloric acid (20 ml) and brine (20 ml).The organic layer was dried (MgSO4) and concentrated in vacuo. The products were separated by column chromatography on silica gel and further purification by recrystallisation from ethyl acetate–hexane or HPLC gave the cinnamamides. N-Benzoyl-N-benzylcinnamamide 1a. Colourless crystals (64%); mp 115–116 8C (Found C 80.9; H 5.5; N 4.4. C23H19- NO2 requires C 80.9; H 5.6; N 4.1%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.30 (1 H d J2,3 15.0) 7.10–7.65 (15 H m) and 7.55 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 49.2 (t) 121.6 (d) 127.5 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 128.8 (d) 130.2 (d) 132.6 (d) 134.4 (s) 136.3 (s) 137.5 (s) 143.4 (d) 169.3 (s) and 173.4 (s); vmax(KBr)/cm21 1695 1655 1620 1350 1205 1190 1140 and 705.N-Benzyl-N-(p-methoxybenzoyl)cinnamamide 1b. Colourless crystals (40%); mp 81–82 8C (Found C 77.7; H 5.7; N 4.0. C24H21NO3 requires C 77.6; H 5.7; N 3.8%); dH(270 MHz; CDCl3) 3.80 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 6.90 (2 H d J 9.0) 7.15 (2 H dd J 2.0 and 7.5) 7.20–7.35 (6 H m) 7.40 (2 H dd J 2.0 and 7.5) 7.55 (1 H d J2,3 15.5) and 7.65 (2 H d J29,39 9.0); dC(22.4 MHz; CDCl3) 49.3 (t) 55.5 (q) 114.1 (d) 121.6 (d) 127.4 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 130.1 (d) 131.3 (d) 134.6 (s) 137.7 (s) 142.9 (d) 163.3 (s) 169.2 (s) and 173.0 (s); vmax(KBr)/cm21 1650 1610 1340 1310 1255 1170 and 1035. N-Benzyl-N-(p-methylbenzoyl)cinnamamide 1c. Colourless crystals (84%); mp 113–114 8C (Found C 81.0; H 5.9; N 4.2. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.35 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 7.10– 7.45 (12 H m) 7.55 (1 H d J2,3 15.5) and 7.55 (2 H d J29,39 10.0); dC(22.4 MHz; CDCl3) 21.6 (q) 49.2 (t) 121.7 (d) 127.4 (d) 127.9 (d) 128.2 (d) 128.5 (d) 128.7 (d) 129.0 (d) 129.5 (d) 130.2 (d) 133.5 (s) 134.6 (s) 137.6 (s) 143.1 (d) 143.5 (s) 169.3 (s) and 173.5 (s); vmax(KBr)/cm21 1695 1655 1620 1345 1310 1185 1135 980 760 and 700.N-Benzyl-N-(m-methylbenzoyl)cinnamamide 1d. Colourless crystals (53%); mp 76–77 8C (Found C 81.0; H 5.9; N 3.9. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.30 (3 H s) 5.15 (2 H s) 6.30 (1 H d J2,3 15.5) 7.10 (2 H dd J49,69 2.0 and J49,59 8.0) 7.20–7.45 (12 H m) and 7.55 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 21.2 (q) 49.1 (t) 121.7 (d) 125.9 (d) 127.4 (d) 127.8 (d) 128.2 (d) 128.5 (d) 128.6 (d) 129.2 (d) 130.1 (d) 133.2 (d) 134.4 (s) 136.2 (s) 137.6 (s) 138.7 (s) 143.0 (d) 169.3 (s) and 173.6 (s); vmax(KBr)/cm21 1695 1655 1620 1345 and 1165.N-Benzyl-N-(o-methylbenzoyl)cinnamamide 1e. Colourless crystals (48%); mp 94–95 8C (Found C 81.0; H 5.8; N 3.8. C24H21NO2 requires C 81.1; H 6.0; N 3.9%); dH(270 MHz; CDCl3) 2.30 (3 H s) 5.10 (2 H s) 6.50 (1 H d J2,3 15.0) 7.10– 7.40 (14 H m) and 7.55 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 19.3 (q) 48.4 (t) 121.0 (d) 125.9 (d) 127.4 (d) 127.6 (d) 127.9 (d) 128.3 (d) 128.4 (d) 128.6 (d) 130.1 (d) 130.9 (d) 131.2 (d) 134.4 (s) 136.3 (s) 137.4 (s) 143.4 (d) 169.3 (s) and 173.2 (s); vmax(KBr)/cm21 1695 1655 1620 1345 1310 1190 1145 1045 and 975. N-Benzyl-N-(p-chlorobenzoyl)cinnamamide 1f. Colourless crystals (23%); mp 121–122 8C (Found C 73.5; H 4.7; N 3.7.C23H18NO2Cl requires C 73.5; H 4.8; N 3.7%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.35 (1 H d J2,3 15.0) 7.20 (2 H dd J 2.0 and 8.5) 7.25–7.40 (8 H m) 7.40 (2 H d J29,39 8.5) 7.55 (2 H d J29,39 8.5) and 7.60 (1 H d J2,3 15.0); dC(22.4 MHz; CDCl3) 49.1 (t) 121.0 (d) 127.5 (d) 127.9 (d) 128.0 (d) 128.5 (d) 128.7 (d) 128.9 (d) 130.0 (d) 130.4 (d) 134.1 (s) 134.5 (s) 137.2 (s) 138.7 (s) 144.0 (d) 169.0 (s) and 172.3 (s); vmax(KBr)/cm21 1700 1650 1615 1335 1310 1185 1135 and 975. N-Benzyl-N-(p-nitrobenzoyl)cinnamamide 1g. Colourless crystals (21%); mp 107–108 8C (Found C 71.5; H 4.4; N 7.4. C23H18N2O4 requires C 71.5; H 4.7; N 7.3%); dH(270 MHz; CDCl3) 5.15 (2 H s) 6.50 (1 H d J2,3 15.5) 7.25–7.40 (m 10 H) 7.60 (1 H d J2,3 15.5) 7.75 (2 H dm J 9.0) and 8.25 (2 H dm J 9.0); dC(22.4 MHz; CDCl3) 44.8 (t) 119.9 (d) 123.7 (d) 127.6 (d) 127.7 (d) 128.0 (d) 128.7 (d) 128.9 (d × 2) 130.8 (d) 133.8 (s) 136.8 (s) 141.8 (s) 145.7 (d) 149.3 (s) 169.0 (s) and 171.4 (s); vmax(KBr)/cm21 1695 1655 1615 1530 1345 1310 1185 865 and 715.N-Benzoyl-N-(1-phenylethyl)cinnamamide 1h. Colourless oil (98%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 6.06 (1 H q JN-a,N-b 7.0) 6.11 (1 H d J2,3 15.5) and 7.00–7.70 (m 16 H); dC(22.4 MHz; CDCl3) 17.4 (q) 54.7 (d) 122.5 (d) 126.8 (d) 126.9 (d) 127.4 (d) 127.9 (d) 128.3 (d) 128.4 (d) 129.8 (d) 130.1 (d) 132.2 (d) 133.9 (s) 136.9 (s) 140.7 (s) 142.3 (d) 168.7 (s) and 173.0 (s); vmax(neat)/cm21 1660 1625 1380 1340 1305 1275 1195 1070 765 and 700 [Found MH+ (FAB) 356.1657. C24H22NO2 (MH+) requires 356.1650]. N-(p-Methoxybenzoyl)-N-(1-phenylethyl)cinnamamide 1i.Colourless oil (74%); dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.0) 3.80 (3 H s) 6.00 (1 H q JN-a,N-b 7.0) 6.15 (1 H d J2,3 15.5) 6.85 (2 H dm J29,39 9.0) 7.10 (2 H dd J 2.0 and 8.0) 7.20–7.35 (6 H m) 7.45 (1 H d J2,3 15.5) 7.50 (2 H dd J 2.0 and 8.0) and 7.65 (2 H dm J29,39 9.0); dC(22.4 MHz; CDCl3) 17.8 (q) 55.1 (d) 55.3 (q) 114.0 (d) 122.5 (d) 127.0 (d) 127.2 (d) 127.7 (d) 128.1 (d) 128.2 (d) 128.6 (d) 129.4 (s) 129.9 (d) 131.4 (d) 134.4 (s) 141.0 (s) 142.2 (d) 163.3 (s) 168.6 (s) and 172.9 (s); vmax(neat)/cm21 1694 1648 1622 1602 1342 1306 1260 1200 1168 788 and 760 [Found MH+ (FAB) 386.1762. C25H24NO3 (MH+) requires 386.1756]. N-(p-Methylbenzoyl)-N-(1-phenylethyl)cinnamamide 1j. Colourless oil (99%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 2.30 (3 H s) 6.05 (1 H q JN-a,N-b 7.0) 6.10 (1 H d J2,3 15.5) 7.05 (2 H dd J 1.5 and 8.0) 7.15–7.35 (8 H m) 7.40 (1 H d J2,3 15.5) 7.50 (2 H dd J 1.5 and 8.0) and 7.55 (2 H dm J29,39 8.0); dC(22.4 MHz; CDCl3) 17.7 (q) 21.4 (q) 55.0 (d) 122.6 (d) 127.0 (d) 127.2 (d) 127.6 (d) 128.1 (d) 128.5 (d) 129.0 (d) 129.3 (d) 129.9 (d) 134.3 (s) 140.9 (s) 142.3 (d) 143.5 (s) 168.8 (s) and 173.3 (s); vmax(neat)/cm21 1694 1658 1620 1450 1374 1338 1306 1272 1196 and 1176 [Found MH+ (FAB) 370.1806.C25H24NO2 (MH+) requires 370.1807]. N-(p-Chlorobenzoyl)-N-(1-phenylethyl)cinnamamide 1k. Colourless oil (91%); dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.0) 6.05 (1 H q JN-a,N-b 7.0) 6.10 (1 H d J2,3 15.5) 7.10 (2 H dd J 1.5 and 8.0) 7.20–7.40 (8 H m) 7.40 (1 H d J2,3 15.5) 7.50 (2 H dd J 1.5 and 8.0) and 7.55 (2 H dm J29,39 8.5); dC(22.4 MHz; CDCl3) 17.6 (q) 54.9 (d) 122.1 (d) 127.0 (d) 127.6 (d) 128.1 (d) 128.5 (d) 128.8 (d) 130.0 (d) 130.1 (d) 133.9 (s) 135.3 (s) 138.6 (s) 140.6 (s) 143.1 (d) 168.7 (s) and 172.0 (s); vmax(neat)/cm21 1696 1652 1620 1340 1192 1172 and 758 [Found MH+ (FAB) 390.1270.C24H21NO2Cl (MH+) requires 390.1261]. N-(p-Cyanobenzoyl)-N-(1-phenylethyl)cinnamamide 1l. Colourless oil (66%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.5) 6.05 (1 H q JN-a,N-b 7.5) 6.15 (1 H d J2,3 15.5) 7.10 (2 H dd J 1.5 and 8.0) 7.25–7.40 (7 H m) 7.50 (2 H dd J 1.5 and J. Chem. Soc. Perkin Trans. 1 1997 81 8.0) and 7.65–7.75 (4 H m); dC(22.4 MHz; CDCl3) 17.6 (q) 54.8 (d) 115.2 (s) 117.4 (s) 121.7 (d) 126.9 (d) 127.7 (d) 128.3 (d) 128.6 (d) 128.7 (d) 130.6 (d) 132.2 (d) 133.6 (s) 140.3 (s) 140.7 (s) 144.3 (d) 169.1 (s) and 171.4 (s); vmax(neat)/cm21 2225w 1654 1340 1274 1192 1174 788 762 and 700 [Found MH+ (FAB) 381.1605.C25H21N2O3 (MH+) requires 381.1603]. N-(p-Nitrobenzoyl)-N-(1-phenylethyl)cinnamamide 1m. Colourless oil (65%); dH(270 MHz; CDCl3) 1.90 (3 H d JN-a,N-b 7.0) 6.05 (1 H q JN-a,N-b 7.0) 6.20 (1 H d J2,3 15.5) 7.15 (2 H dd J 1.5 and 7.5) 7.25–7.45 (7 H m) 7.50 (2 H dd J 1.5 and 7.5) 7.75 (2 H dm J29,39 9.0) and 8.20 (2 H dm J29,39 9.0); dC(22.4 MHz; CDCl3) 17.6 (q) 54.8 (d) 121.4 (d) 123.7 (d) 126.9 (d) 127.4 (d) 127.8 (d) 128.4 (d) 128.7 (d) 129.0 (d) 130.6 (d) 133.6 (s) 140.2 (s) 142.4 (s) 144.7 (d) 149.2 (s) 169.3 (s) and 171.2 (s); vmax(neat)/cm21 1656 1622 1526 1350 1306 1274 1190 848 792 760 714 and 700 [Found MH+ (FAB) 401.1503.C24H21N2O4 (MH+) requires 401.1502]. N-Benzoyl-N-(1-phenylpropyl)cinnamamide 1n. Colourless oil (95%); dH(270 MHz; CDCl3) 1.05 (3 H t JN-b,N-g 7.5) 2.30 (1 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 14.0 and JN-b,N-g 7.5) 2.50 (1 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 14.0 and JN-b,N-g 7.5) 5.80 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 6.05 (1 H d J2,3 15.5) 7.00 (2 H ddd J 1.5 1.5 and 7.5) 7.16–7.50 (10 H m) 7.55 (2 H ddd J 1.5 1.5 and 7.5) and 7.65 (2 H ddd J 2.5 3.0 and 8.5); dC(22.4 MHz; CDCl3) 11.6 (q) 24.6 (t) 61.8 (d) 122.9 (d) 127.2 (d) 127.6 (d) 128.0 (d) 128.5 (d) 128.6 (d) 128.8 (d) 130.0 (d) 132.4 (d) 134.1 (s) 137.2 (s) 140.1 (s) 142.4 (d) 169.5 (s) and 173.1 (s); vmax(neat)/cm21 1696 1656 1620 1338 1192 1176 788 760 and 698 [Found MH+ (FAB) 370.1804. C25H24NO2 (MH+) requires 370.1807].N-Benzoyl-N-(diphenylmethyl)cinnamamide 1o. White solid (32%) (Found C 82.3; H 6.0; N 3.2. C29H23NO2?1/3H2O requires C 82.3; H 5.6; N 3.3%); dH(270 MHz; CDCl3) 6.15 (1 H d J2,3 15.5) 7.05 (2 H dd J 1.5 and 8.0) 7.15–7.50 (17 H m) and 7.70 (2 H ddd J 2.5 4.5 and 8.5); dC(22.4 MHz; CDCl3) 63.8 (d) 122.6 (d) 127.4 (d) 127.8 (d) 128.2 (d) 128.6 (d) 128.8 (d) 128.9 (d) 129.0 (d) 130.2 (d) 132.8 (d) 134.3 (s) 137.1 (s) 138.9 (s) 143.2 (d) 169.0 (s) and 172.8 (s); vmax(KBr)/ cm21 3050 2930 1695 1660 1620 1340 1190 985 765 and 695. N-Benzoyl-N-(1-methyl-l-phenylethyl)cinnamamide 1p. Colourless oil (73%); dH(270 MHz; CDCl3) 1.85 (6 H s) 6.20 (1 H d J2,3 15.5) 7.10–7.65 (13 H m) 7.45 (1 H d J2,3 15.5) and 8.05 (2 H ddd J 1.5 3.0 and 8.0); dC(22.4 MHz; CDCl3) 29.3 (q) 62.9 (s) 121.5 (d) 125.0 (d) 126.4 (d) 127.7 (d) 128.2 (d) 128.5 (d) 129.0 (d) 129.8 (d) 130.1 (d) 133.8 (d) 134.4 (s) 136.6 (s) 142.7 (d) 147.2 (s) 166.2 (s) and 174.8 (s); vmax(neat)/cm21 1700 1662 1622 1344 1268 1232 1158 784 764 and 698 [Found MH+ (FAB) 370.1813.C25H24NO2 (MH+) requires 370.1807]. N-Acetyl-N-benzylcinnamamide 3a. Colourless crystals (26%); mp 92–93 8C (Found C 77.4; H 6.0; N 4.9. C18H17NO2 requires C 77.4; H 6.1; N 5.0%); dH(270 MHz; CDCl3) 2.50 (3 H s) 5.05 (2 H s) 7.05 (1 H d J2,3 15.5) 7.20–7.40 (8 H m) 7.50 (1 H d J 7.5) 7.50 (1 H d J 7.5) and 7.75 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 26.0 (q) 47.5 (t) 120.1 (d) 126.2 (d) 127.3 (d) 128.1 (d) 128.7 (d) 130.3 (d) 134.4 (s) 137.0 (s) 145.0 (d) 169.1 (s) and 173.4 (s); vmax(KBr)/cm21 1700 1610 1380 1340 1195 and 1085. N-Acetyl-N-(diphenylmethyl)cinnamamide 3b.Colourless oil (99%); dH(270 MHz; CDCl3) 2.40 (3 H s) 6.70 (1 H d J2,3 15.5) 7.10 (1 H s) 7.25–7.35 (15 H m) and 7.50 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 26.3 (q) 61.6 (d) 121.6 (d) 127.3 (d) 128.0 (d) 128.2 (d) 128.6 (d) 130.2 (d) 134.1 (s) 138.4 (s) 144.0 (d) 169.9 (s) and 173.0 (s); vmax(neat)/cm21 1684 1622 1378 1334 1244 1172 784 760 and 700 [Found MH+ (FAB) 356.1652. C24H22NO2 (MH+) requires 356.1650]. General procedure for the preparation of the cinnamamides 5 To a solution of cinnamic acid (1 mmol) in 5 ml of acetonitrile was added triethylamine (1 equiv.) at room temperature. To a solution of carbodiimide (1.2 equiv.) in acetonitrile (10 ml) was added dropwise the resulting solution. After complete addition the mixture was further stirred at room temperature for 24 h after which it was acidified with 1 M hydrochloric acid (50 ml) and extracted with diethyl ether (3 × 20 ml).The combined extracts were dried (MgSO4) and concentrated in vacuo. The products were separated by column chromatography on silica gel and further purification by HPLC gave the cinnamamides. N-Benzyl-N-(benzylaminocarbonyl)cinnamamide 5a. Colourless crystals (76%); mp 111–112 8C (Found C 77.6; H 6.0; N 7.5. C24H22N2O2 requires C 77.8; H 6.0; N 7.6%); dH(270 MHz; CDCl3) 4.60 (2 H d JN9H,N9-a 5.5) 5.20 (2 H s) 6.80 (1 H d J2,3 15.5) 7.25–7.40 (16 H m) and 7.70 (1 H d J2,3 15.5); dC(22.4 MHz; CDCl3) 44.7 (t) 47.6 (t) 118.7 (d) 126.1 (d) 127.3 (d) 127.4 (d) 127.5 (d) 128.1 (d) 128.6 (d) 128.9 (d) 130.5 (d) 134.3 (s) 137.8 (s) 138.3 (s) 145.9 (d) 155.4 (s) and 170.2 (s); vmax(KBr)/cm21 1640 1535 1355 1185 and 705.N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]cinnamamide 5b. Colourless oil (91%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.75 (3 H d JN-a,N-b 7.0) 5.07 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.60 (1 H d J2,3 16.0) 7.20–7.40 (15 H m) 7.60 (1 H d J2,3 16.0) and 9.00 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 22.6 (q) 50.8 (d) 51.4 (d) 120.3 (d) 126.0 (d) 126.3 (d) 127.1 (d) 127.2 (d) 128.0 (d) 128.5 (d) 128.6 (d) 128.7 (d) 130.1 (d) 134.5 (s) 141.8 (s) 143.2 (s) 144.0 (d) 154.6 (s) and 169.3 (s); vmax(neat)/cm21 1710 1656 1610 1522 1498 1376 786 762 and 700 [Found MH+ (FAB) 399.2073. C26H27N2O2 (MH+) requires 399.2072]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- methoxycinnamamide 5c.Colourless oil (75%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.75 (3 H d JN-a,N-b 7.0) 3.80 (3 H s) 5.10 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.45 (1 H d J2,3 15.0) 6.80 (2 H d J29,39 9.0) 7.20 (2 H d J29,39 9.0) 7.20–7.40 (10 H m) 7.60 (1 H d J2,3 15.0) and 9.15 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 22.6 (q) 50.7 (d) 51.4 (d) 55.3 (q) 114.2 (d) 117.8 (d) 126.0 (d) 127.0 (d) 127.1 (d) 127.3 (d) 128.3 (d) 128.6 (d) 128.7 (d) 130.0 (d) 142.0 (s) 143.4 (s) 143.8 (s) 154.8 (d) 161.3 (s) and 169.7 (s); vmax(neat)/cm21 1708 1650 1598 1576 1512 1452 782 762 and 700 [Found MH+ (FAB) 433.1674. C27H29N2O3 (MH+) requires 433.1683]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- methylcinnamamide 5d. Colourless oil (72%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.0) 1.80 (3 H d JN-a,N-b 7.0) 2.30 (3 H s) 5.10 (1 H dq JN9H,N0-a 7.0 and JN9-a,N9-b 7.0) 6.30 (1 H q JN-a,N-b 7.0) 6.55 (1 H d J2,3 15.0) 7.10–7.40 (14 H m) 7.60 (1 H d J2,3 15.0) and 9.05 (1 H br); dC(22.4 MHz; CDCl3) 18.4 (q) 21.3 (q) 22.6 (q) 50.7 (d) 51.4 (d) 119.2 (d) 126.0 (d) 127.06 (d) 127.12 (d) 128.0 (d) 128.6 (d) 128.7 (d) 129.5 (d) 131.8 (d) 140.6 (s) 141.9 (s) 143.3 (s) 144.0 (d) 154.7 (s) and 169.6 (s); vmax(neat)/cm21 1704 1650 1602 1514 1498 1368 812 786 760 and 700 [Found MH+ (FAB) 413.2233.C27H29N2O2 (MH+) requires 413.2229]. N-(1-Phenylethyl)-N-[(1-phenylethyl)aminocarbonyl]-49- chlorocinnamamide 5e. Colourless oil (86%); dH(270 MHz; CDCl3) 1.55 (3 H d JN9-a,N9-b 7.5) 1.75 (3 H d JN-a,N-b 7.5) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.30 (1 H q JN-a,N-b 7.5) 6.55 (1 H d J2,3 15.5) 7.10–7.40 (14 H m) 7.50 (1 H d J2,3 15.5) and 8.80 (1 H br); dC(22.4 MHz; CDCl3) 18.3 (q) 22.1 (q) 50.6 (d) 51.6 (d) 120.3 (d) 125.7 (d) 125.96 (d) 126.02 (d) 127.1 (d) 128.1 (d) 128.5 (d) 128.8 (d) 128.9 (d) 132.7 (s) 135.7 (s) 141.7 (s) 142.1 (d) 142.9 (s) 154.1 (s) and 168.1 (s); vmax(neat)/cm21 1702 1656 1610 1530 1494 1372 1262 1094 786 762 and 700 [Found MH+ (FAB) 399.2073.C26H26N2O2Cl (MH+) requires 399.2072]. General procedure for the photocycloaddition of the cinnamamides 2 A solution containing cinnamamide (0.1 mmol) and benzil (1 equiv.) in benzene (5 ml) in a Pyrex test tube was irradiated with 82 J. Chem. Soc. Perkin Trans. 1 1997 a high-pressure mercury lamp under an Ar atmosphere at room temperature the reaction being monitored by HPLC and a UV detector.After irradiation the mixture was evaporated in vacuo. The products were separated by column chromatography on silica gel (ethyl acetate–hexane) and purified by HPLC (ethyl acetate–hexane) to give the photocycloadducts. (5S*,6R*)-N-Benzyl-6-phenyl-3-azatricyclo[5.2.2.01,5]undeca- 8,10-diene-2,4-dione 2a. Colourless oil (93%); dH(270 MHz; CDCl3) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 1.0 and J5,6 7.0) 3.90 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 5.5 and J7,10 6.0) 4.65 (2 H s) 6.05 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 42.2 (t) 44.9 (d) 45.1 (d) 55.8 (s) 57.6 (d) 126.8 (d) 127.1 (d) 127.8 (d) 128.5 (d) 128.6 (d) 132.2 (d) 132.5 (d) 133.8 (d) 136.1 (s) 141.8 (d) 142.6 (s) 175.0 (s) and 176.0 (s); vmax(neat)/cm21 1712 1384 1344 1131 794 758 and 700 [Found MH+ (FAB) 342.1478.C23H20NO2 (MH+) requires 342.1494]. (5S*,6R*)-N-Benzyl-7-methyl-6-phenyl-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2c. Colourless oil (>95%); dH(90 MHz; C6D6) 1.00 (3 H s) 2.65 (1 H d J5,6 7.5) 2.95 (1 H d J5,6 7.5) 4.70 (2 H d J 2.0) 5.80 (1 H d J8,9 7.5) 6.00 (1 H d J10,11 7.1) 6.20 (1 H d J10,11 7.0) 6.90 (1 H d J8,9 7.5) and 6.97–7.31 (10 H m); the 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product. (1R*,5S*,6R*,7S*)-N-Benzyl-10-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a major product of 2d).Colourless oil (47%); dH(270 MHz; CDCl3) 1.90 (3 H d J10-Me,11 2.0) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 1.5 and J5,6 7.0) 3.60 (1 H dddd J6,7 1.5 J7,9 1.5 J7,11 2.0 and J7,8 5.5) 4.65 (2 H d J2,5 2.5) 5.65 (1 H dd J7,11 2.0 and J10-Me,11 2.0) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 7.05 (1 H dd J7,9 1.5 and J8,9 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 18.5 (q) 42.2 (t) 44.6 (d) 50.6 (d) 56.3 (s) 58.9 (d) 125.1 (d) 126.8 (d) 127.1 (d) 127.8 (d) 128.6 (d) 128.7 (d) 132.1 (d) 134.3 (d) 136.2 (s) 142.9 (s) 152.1 (s) 175.4 (s) and 176.2 (s); vmax(neat)/cm21 1716 1386 1344 790 750 and 700 [Found MH+ (FAB) 356.1656. C24H22NO2 (MH+) requires 356.1651]. (1S*,5S*,6R*,7R*)-N-Benzyl-8-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a minor product of 2d). Colourless oil (36%); dH(270 MHz; CDCl3) 1.80 (3 H d J8-Me,9 2.0) 3.00 (1 H d J5,6 7.0) 3.15 (1 H dd J6,7 1.5 and J5,6 7.0) 3.50 (1 H dddd J6,7 1.5 J7,11 1.5 J7,9 2.0 and J7,10 5.5) 4.65 (s 2 H) 6.05 (1 H dd J7,11 1.5 and J10,11 7.5) 6.65 (1 H dd J7,9 2.0 and J8-Me,9 2.0) 6.90 (1 H dd J7,10 5.5 and J10,11 7.5) and 7.15–7.40 (10 H m); dC(22.4 MHz; CDCl3) 21.6 (q) 42.1 (t) 44.7 (d) 51.7 (d) 51.7 (d) 55.6 (s) 57.6 (d) 126.2 (d) 127.0 (d) 127.1 (d) 127.8 (d) 128.6 (d × 2) 133.0 (d) 136.2 (s) 141.5 (d) 142.1 (s) 142.7 (s) 175.0 (s) and 176.3 (s); vmax(neat)/cm21 1722 1386 1342 782 756 and 700 [Found MH+ (FAB) 356.1652.C24H22NO2 (MH+) requires 356.1651]. (1R*,5S*,6R*,7S*)-N-Benzyl-11-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a minor product of 2e). Colourless oil (13%); dH(270 MHz; CDCl3) 1.45 (3 H d J11-Me,10 2.0) 2.75 (1 H d J5,6 7.5) 3.25 (1 H dd J6,7 1.5 and J5,6 7.5) 3.80 (1 H dddd J6,7 1.5 J 7,9 1.5 J7,8 5.0 and J 7,10 6.5) 4.65 (2 H s) 6.40 (1 H dd J11-Me,10 2.0 and J7,10 6.5) 6.45 (1 H dd J7,8 5.0 and J8,9 7.0) 7.05 (1 H dd J7,9 1.5 and J8,9 7.0) 7.15– 7.35 (8 H m) and 7.45 (2 H dd J 2.0 and 7.5); dC(22.4 MHz; CDCl3) 16.9 (q) 42.2 (t) 45.0 (d) 45.2 (d) 58.1 (d) 59.0 (s) 126.8 (d) 127.1 (d) 128.0 (d) 128.6 (d) 129.4 (d) 133.3 (d) 134.1 (d) 134.6 (d) 136.0 (s) 140.3 (s) 142.9 (s) 174.6 (s) and 175.5 (s); vmax(neat)/cm21 1714 1384 1342 1070 788 756 728 and 700 [MH+ (FAB) 356.1649.C24H22NO2 (MH+) requires 356.1650]. (1R*,5S*,6R*,7R*)-N-Benzyl-9-methyl-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione (a major product of 2e).Colourless oil (22%); dH(270 MHz; CDCl3) 2.10 (3 H d J9-Me,8 1.5) 2.75 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 2.0 and J5,6 7.0) 3.75 (1 H dddd J6,7 2.0 J7,11 2.0 J7,8 5.5 and J7,10 6.5) 4.65 (2 H s) 5.95 (1 H dd J9-Me,8 1.5 and J7,8 5.5) 6.00 (1 H dd J7,11 2.0 and J10,11 7.0) 6.90 (1 H dd J7,10 6.5 and J10,11 7.0) and 7.15– 7.40 (10 H m); dC(22.4 MHz; CDCl3) 16.1 (q) 42.1 (t) 44.8 (d) 45.4 (d) 57.1 (d) 57.5 (s) 125.5 (d) 126.7 (d) 127.2 (d) 127.8 (d) 128.6 (d) 128.7 (d) 131.8 (d) 136.2 (s) 142.6 (d) 142.9 (s) 144.8 (s) 175.3 (s) and 175.8 (s); vmax(neat)/cm21 1718 1432 1384 1348 1072 788 756 and 700 [Found MH+ (FAB) 356.1658. C24H22NO2 (MH+) requires 356.1651]. (5S*,6R*)-N-Benzyl-7-chloro-6-phenyl-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2f. Colourless oil (71%); dH(270 MHz; CDCl3) 3.00 (1 H d J5,6 7.0) 3.40 (1 H d J5,6 7.0) 4.65 (2 H s) 6.10 (1 H d J10,11 7.0) 6.45 (1 H d J8,9 8.5) 6.90 (1 H d J10,11 7.0) 7.05 (1 H d J8,9 8.5) and 7.20–7.35 (10 H m); the 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product.(5S*,6R*)-6-Phenyl-N-(1-phenylethyl)-3-azatricyclo[5.2. 2.01,5]undeca-8,10-diene-2,4-dione 2h. (99%) Diastereoisomer A.— Colourless oil; dH(270 MHz; CDCl3) 1.85 (3 H d JN-a,N-b 7.5) 2.70 (1 H d J5,6 7.5) 3.20 (1 H dd J6,7 1.5 and J5,6 7.5) 3.90 (1 H ddddd J7,9 1.0 J7,11 1.0 J6,7 1.5 J7,8 5.5 and J7,10 6.0) 5.40 (1 H q JN-a,N-b 7.5) 6.00 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.00 (1 H dd J7,9 1.0 and J8,9 7.5) 7.10–7.40 (8 H m) and 7.45 (2 H dd J 1.0 and 7.0); dC(22.4 MHz; CDCl3) 16.9 (q) 45.1 (d) 45.2 (d) 49.8 (d) 55.7 (s) 57.5 (d) 126.9 (d) 127.2 (d) 127.4 (d) 127.7 (d) 128.4 (d) 128.7 (d) 132.0 (d) 132.6 (d) 133.8 (d) 139.5 (s) 141.9 (d) 142.7 (s) 175.2 (s) and 176.1 (s); vmax(neat)/cm21 3060 3028 2972 1776 1710 1500 1374 1346 758 and 698.Diastereoisomer B.—Colourless oil; dH(270 MHz; CDCl3) 1.80 (3 H d JN-a,N-b 7.5) 2.75 (1 H d J5,6 7.5) 3.20 (1 H dd J6,7 1.5 and J5,6 7.5) 3.90 (1 H ddddd J7,9 1.0 J7,11 1.0 J6,7 1.5 J7,8 5.5 and J7,10 6.0) 5.45 (1 H q JN-a,N-b 7.5) 6.10 (1 H dd J7,11 1.0 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 6.0 and J10,11 7.5) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) 7.10– 7.40 (8 H m) and 7.45 (2 H dd J 1.0 and 7.0); dC(22.4 MHz; CDCl3) 16.6 (q) 45.0 (d) 45.1 (d) 50.1 (d) 55.7 (s) 57.6 (d) 126.9 (d) 127.2 (d × 2) 127.7 (d) 128.5 (d) 128.7 (d) 132.1 (d) 132.6 (d) 133.9 (d) 140.2 (s) 142.0 (d) 142.7 (s) 175.1 (s) and 176.1 (s); vmax(neat)/cm21 1715 1500 1460 1378 1342 1154 1050 1030 782 758 and 698 [Found MH+ (FAB) 356.1654.C24H22NO2 (MH+) requires 356.1651]. A mixture of diastereoisomers of (5S*,6R*)-7,8,9,10,11- pentadeuterio-6-phenyl-N-(1-phenylethyl)-3-azatricyclo- [5.2.2.01,5]undeca-8,10-diene-2,4-dione 2h9. Colourless oil (99%); dH(270 MHz; CDCl3) 1.80 (1.5 H d JN-a,N-b 7.5) 1.85 (1.5 H d JN-a,N-b 7.5) 2.70 (0.5 H d J5,6 7.5) 2.75 (0.5 H d J5,6 7.5) 3.15 (0.5 H dd J5,6 7.5) 3.20 (0.5 H d J5,6 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 7.15–7.40 (8 H m) and 7.45 (2 H dd and J 1.0 7.0) [Found MH+ (FAB) 361.1970. C24H17D5NO2 (MH+) requires 361.1964].A mixture of diastereoisomers of (5S*,6R*)-7-methyl-6- phenyl-N-(1-phenylethyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10- diene-2,4-dione 2j. Colourless oil ( >99%); dH(270 MHz; C6D6) 1.20 (1.5 H s) 1.20 (1.5 H s) 2.05 (1.5 H d JN-a,N-b 7.0) 2.10 (1.5 H d JN-a,N-b 7.0) 2.95 (0.5 H d J5,6 7.0) 3.00 (0.5 H d J5,6 7.0) 3.20 (0.5 H d J5,6 7.0) 3.25 (0.5 H d J5,6 7.0) 5.85 (0.5 H q JN-a,N-b 7.0) 5.85 (0.5 H q JN-a,N-b 7.0) 6.00 (1 H d J10,11 7.0) 6.25 (0.5 H d J10,11 7.0) 6.35 (0.5 H d J10,11 7.0) 6.45 (0.5 H d J10,11 7.0) 6.45 (0.5 H d J10,11 7.0) 7.10 (0.5 H d J8,9 7.5) 7.15 (0.5 H d J8,9 7.5) and 7.25–7.60 (10 H m). The 13C NMR IR and HRMS spectra were not measured because of the unstable nature of the product. A mixture of diastereoisomers of (5S*,6R*)-7-chloro-6-phenyl- N-(1-phenylethyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2k.Colourless oil (92%); dH(270 MHz; CDCl3) 1.80 (1.5 H d JN-a,N-b 7.5) 1.80 (1.5 H d JN-a,N-b 7.5) 2.95 (0.5 H d J5,6 7.0) 2.95 (0.5 H d J5,6 7.0) 3.35 (0.5 H d J5,6 7.0) 3.40 (0.5 H, J. Chem. Soc. Perkin Trans. 1 1997 83 d J5,6 7.0) 5.35 (0.5 H q JN-a,N-b 7.5) 5.40 (0.5 H q JN-a,N-b 7.5) 6.00 (0.5 H d J10,11 7.0) 6.10 (0.5 H d J10,11 7.0) 6.40 (0.5 H d J8,9 7.5) 6.45 (0.5 H d J8,9 7.5) 6.85 (1 H d J10,11 7.0) 7.00 (0.5 H d J 7.5) 7.05 (0.5 H d J10,11 7.5) and 7.20–7.40 (10 H m); vmax(neat)/cm21 1718 1658 1620 1378 1340 760 and 700. The 13C NMR and HRMS spectra were not measured because of the unstable nature of the product. A mixture of diastereoisomers of (5S*,6R*)-6-phenyl-N-(1- phenylpropyl)-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2n.Colourless oil (87%); dH(270 MHz; CDCl3) 0.95 (1.5 H t JN-b,N-g 7.5) 0.95 (1.5 H t JN-b,N-g 7.5) 2.20 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.25 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.45 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.55 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.65 (0.5 H d J5,6 7.0) 2.70 (0.5 H d J5,6 7.0) 3.20 (1 H dd J6,7 and J5,6 7.0) 3.85–3.90 (1 H m) 5.10 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 6.00 (0.5 H dd J7,11 1.0 and J10,11 7.0) 6.10 (0.5 H dd J7,11 1.0 and J10,11 7.0) 6.45 (0.5 H dd J7,8 5.5 and J8,9 7.5) 6.45 (0.5 H dd J7,8 5.5 and J8,9 7.5) 6.90 (1 H dd J7,10 7.0 and J10,11 7.0) 7.00 (0.5 H dd J7,9 1.5 and J8,9 7.5) 7.05 (0.5 H dd J7,9 1.5 and J8,9 7.5) 7.18–7.37 (8 H m) and 7.45 (2 H d J 7.5); vmax(neat)/ cm21 1714 1380 1346 788 758 and 700 [Found MH+ (FAB) 370.1800.C25H24NO2 (MH+) requires 370.1807]. A mixture of diastereoisomers of (5S*,6R*)-7,8,9,10,11-pentadeuterio- 6-phenyl-N-(1-phenylpropyl)-3-azatricyclo[5.2.2.01,5]undeca- 8,10-diene-2,4-dione 2n9. Colourless oil (79%); dH(270 MHz; CDCl3) 0.95 (1.5 H t JN-b,N-g 7.5) 0.95 (1.5 H t JN-b,N-g 7.5) 2.20 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.25 (0.5 H ddq JN-a,N-b1 6.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.45 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.55 (0.5 H ddq JN-a,N-b2 9.5 JN-b1,N-b2 13.5 and JN-b,N-g 7.5) 2.65 (0.5 H d J5,6 7.0) 2.70 (0.5 H d J5,6 7.0) 3.20 (1 H d J5,6 7.0) 5.10 (1 H dd JN-a,N-b1 6.5 and JN-a,N-b2 9.5) 7.20–7.35 (8 H m) and 7.45 (2 H d J 7.5) [Found MH+ (FAB) 375.2122.C25H19D5NO2 (MH+) requires 375.2121]. (5S*,6R*)-6-Phenyl-N-(diphenylmethyl)-3-azatricyclo[5.2.2. 01,5]undeca-8,10-diene-2,4-dione 2o. Colourless oil (98%); dH(270 MHz; CDCl3) 2.80 (1 H d J5,6 7.0) 3.25 (1 H dd J6,7 1.5 and J5,6 7.0) 3.90 (1 H ddddd J7,9 1.0 J6,7 1.5 J7,11 1.5 J7,8 6.0 and J7,10 6.5) 6.10 (1 H dd J7,11 1.5 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.55 (1 H s) 6.95 (1 H dd J7,10 6.5 and J10,11 7.0) 7.05 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.15–7.40 (15 H m); dC(22.4 MHz; CDCl3) 45.1 (d) 45.2 (d) 55.8 (s) 57.7 (d) 58.1 (d) 126.9 (d) 127.2 (d) 127.7 (d) 127.8 (d) 128.4 (d) 128.5 (d) 128.7 (d) 131.9 (d) 132.7 (d) 133.8 (d) 137.7 (s) 138.0 (s) 142.1 (d) 142.6 (s) 174.9 (s) and 175.7 (s); vmax(neat)/cm21 1718 1662 1498 1378 1346 786 738 and 700 [Found MH+ (FAB) 418.1807.C29H24NO2 (MH+) requires 418.1807]. (5S*,6R*)-7,8,9,10,11-Pentadeuterio-6-phenyl-N-(diphenylmethyl)- 3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4-dione 2o9. Colourless oil (99%); dH(270 MHz; CDCl3) 2.80 (1 H d J5,6 7.0) 3.25 (1 H d J5,6 7.0) 6.55 (1 H s) and 7.15–7.40 (15 H m) [Found MH+ (FAB) 423.2122. C29H19D5NO2 (MH+) requires 423.2121]. (5S*,6R*)-N-(1-Methyl-1-phenylethyl)-6-phenyl-3-azatricyclo[ 5.2.2.01,5]undeca-8,10-diene-2,4-dione 2p. Colourless oil (84%); dH(270 MHz; CDCl3) 1.90 (3 H s) 1.95 (3 H s) 2.70 (1 H d J5,6 7.0) 3.20 (1 H dd J6,7 0.5 and J5,6 7.0) 3.85 (1 H ddddd J6,7 0.5 J7,9 1.0 J7,11 1.0 J7,8 5.5 and J7,10 6.5) 6.20 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.95 (1 H dd J7,10 6.5 and J10,11 7.0) 7.00 (1 H dd J7,9 1.0 and J8,9 7.5) and 7.20–7.35 (10 H m); dC(22.4 MHz; CDCl3) 28.4 (q) 28.9 (q) 45.1 (d) 45.2 (d) 55.8 (s) 58.0 (d) 61.8 (s) 124.3 (d) 126.8 (d) 127.2 (d) 128.3 (d) 128.6 (d) 131.9 (d) 132.6 (d) 134.1 (d) 142.0 (d) 142.8 (s) 146.3 (s) 175.9 (s) and 176.7 (s); vmax(neat)/cm21 1780 1724 1368 1328 1220 1060 784 756 and 700 [Found MH+ (FAB) 370.1809.C25H24NO2 (MH+) requires 370.1807]. (5S*,6R*)-7,8,9,10,11-Pentadeuterio-N-(1-methyl-1-phenylethyl)- 6-phenyl-3-azatricyclo[5.2.2.01,5]undeca-8,10-diene-2,4- dione 2p9. Colourless oil (99%); dH(270 MHz; CDCl3) 1.90 (3 H s) 1.95 (3 H s) 2.70 (1 H d J5,6 7.0) 3.20 (1 H d J5,6 7.0) and 7.20–7.35 (10 H m) [Found MH+ (FAB) 375.2117. C25H19D5NO2 (MH+) requires 375.2121].(2S*,5S*,6R*)-N-Acetyl-2,6-diphenyl-3-azatricyclo[5.2.2.01,5]- undeca-8,10-dien-4-one 4b. Colourless oil (42%); dH(270 MHz; CDCl3) 2.55 (3 H s) 2.80 (1 H d J5,6 6.0) 3.20 (1 H dd J6,7 1.5 and J5,6 6.0) 3.80–3.85 (1 H m) 5.85 (1 H s) 6.25–6.30 (3 H m) 6.85 (1 H dd J7,10 6.5 and J10,11 7.5) and 7.15–7.45 (10 H m); dC(22.4 MHz; CDCl3) 25.2 (q) 45.3 (d) 46.5 (d) 51.7 (s) 56.5 (d) 64.5 (d) 126.2 (d) 126.6 (d) 127.3 (d) 128.0 (d) 128.5 (d) 129.0 (d) 132.7 (d) 134.7 (d) 136.0 (d) 141.6 (d) 143.3 (s) 170.7 (s) and 175.0 (s); vmax(neat)/cm21 2972 2924 1744 1690 1374 1334 1280 and 666 [Found MH+ (FAB) 356.1638. C24H22NO2 (MH+) requires 356.1650]. (2S*,5S*,6R*)-2-Methyl-6-phenyl-N-[(1-phenylethyl)aminocarbonyl]- 3-azatricyclo[5.2.2.01,5]undeca-8,10-dien-4-one 6b. Colourless oil (56%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 7.0) 1.50 (3 H d JN9-a,N9-b 7.5) 2.75 (1 H d J5,6 6.5) 3.15 (1 H dd J6,7 2.0 and J5,6 6.5) 3.90 (1 H ddddd J7,9 0.5 J7,11 0.5 J6,7 2.0 J7,8 5.5 and J7,10 6.5) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 0.5 and J10,11 7.5) 6.45 (1 H dd J7,8 5.5 and J8,9 7.5) 6.70 (1 H dd J7,9 0.5 and J8,9 7.5) 6.80 (1 H dd J7,10 6.5 and J10,11 7.5) 7.15–7.35 (10 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 44.9 (d) 46.0 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.5 (d) 125.9 (d) 126.6 (d) 127.2 (d × 2) 128.6 (d × 2) 133.6 (d) 134.5 (d) 136.2 (d) 141.3 (d) 143.5 (s) 152.1 (s) and 176.3 (s); vmax(neat)/cm21 1714 1534 1370 1342 1232 760 718 and 700 [Found MH+ (FAB) 399.2077.C26H27N2O2 (MH+) requires 399.2072].(2S*,5S*,6R*)-2-Methyl-6-(4-methoxyphenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6c. Colourless oil (55%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 7.0 Hz) 1.50 (3 H d JN9-a,N9-b 7.3) 2.70 (1 H d J5,6 6.5 Hz) 3.13 (1 H dd J6,7 1.5 and J5,6 6.5) 3.75 (3 H s) 3.85 (1 H ddddd J6,7 1.5 J7,9 1.5 J7,11 1.5 J7,8 6.0 and J7,10 6.0) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 1.5 and J10,11 7.5) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.5 and J8,9 7.5) 6.80 (2 H d J29,39 9.0) 6.80 (1 H dd J7,10 6.0 and J10,11 7.5) 7.15 (2 H d J29,39 9.0) 7.15–7.35 (5 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 45.2 (d) 49.7 (d) 51.3 (d) 55.3 (s) 57.4 (d) 57.5 (d) 114.0 (d) 125.9 (d) 127.2 (d) 128.2 (d) 128.6 (d) 133.6 (d) 134.5 (d) 135.7 (d) 136.0 (d) 141.3 (s) 143.6 (s) 152.2 (s) 158.3 (s) and 176.4 (s); vmax(neat)/cm21 1715 1520 1375 1250 1180 765 and 705 [Found MH+ (FAB) 429.2161.C27H29N2O3 (MH+) requires 429.2178]. (2S*,5S*,6R*)-2-Methyl-6-(4-methylphenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6d. Colourless oil (56%); dH(270 MHz; CDCl3) 1.50 (3 H d J2,2-Me 6.5) 1.50 (3 H d JN9-a,N9-b 7.0) 2.30 (3 H s) 2.70 (1 H d J5,6 6.5) 3.10 (1 H dd J6,7 1.0 and J5,6 6.5) 3.85 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 6.0 and J7,10 6.5) 4.85 (1 H q J2,2-Me 6.5) 5.05 (1 H dq JN9H,N9-a 7.0 and JN9-a,N9-b 7.0) 6.15 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.0 and J8,9 7.5) 6.80 (1 H dd J7,10 6.5 and J10,11 7.0) 7.10 (2 H d J29,39 8.5) 7.15 (2 H d J29,39 8.5) 7.15–7.35 (5 H m) and 8.70 (1 H d JN9H,N9-a 7.0); dC(22.4 MHz; CDCl3) 14.7 (q) 20.9 (q) 22.9 (q) 45.0 (d) 45.6 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.4 (d) 125.9 (d) 127.1 (d) 128.6 (d) 129.2 (d) 133.7 (d) 134.4 (d) 136.1 (d) 136.2 (s) 140.5 (s) 141.3 (d) 143.6 (s) 152.1 (s) and 176.4 (s); vmax(neat)/cm21 2972 1716 1690 1532 1372 1344 1232 and 762 [Found MH+ (FAB) 413.2222.C27H29N2O2 (MH+) requires 413.2229]. (2S*,5S*,6R*)-2-Methyl-6-(4-chlorophenyl)-N-[(1-phenylethyl) aminocarbonyl]-3-azatricyclo[5.2.2.01,5]undeca-8,10-dien- 4-one 6e. Colourless oil (61%); dH(270 MHz; CDCl3) 1.50 (3 H, 84 J. Chem. Soc. Perkin Trans. 1 1997 d J2,2-Me 7.0) 1.50 (3 H d JN9-a,N9-b 7.5) 2.65 (1 H d J5,6 6.0) 3.10 (1 H dd J6,7 1.0 and J5,6 6.0) 3.85 (1 H ddddd J6,7 1.0 J7,9 1.0 J7,11 1.0 J7,8 6.0 and J7,10 6.0) 4.85 (1 H q J2,2-Me 7.0) 5.05 (1 H dq JN9H,N9-a 7.5 and JN9-a,N9-b 7.5) 6.15 (1 H dd J7,11 1.0 and J10,11 7.0) 6.45 (1 H dd J7,8 6.0 and J8,9 7.5) 6.70 (1 H dd J7,9 1.0 and J8,9 7.5) 6.80 (1 H dd J7,10 6.0 and J10,11 7.0) 7.15– 7.40 (9 H m) and 8.70 (1 H d J 7.5); dC(22.4 MHz; CDCl3) 14.7 (q) 22.9 (q) 44.7 (d) 45.4 (d) 49.7 (d) 51.3 (s) 57.3 (d) 57.5 (d) 125.9 (d) 127.2 (d) 128.6 (d) 128.6 (d) 132.4 (s) 133.3 (d) 134.9 (d) 136.3 (d) 141.1 (d) 142.0 (s) 143.4 (s) 152.0 (s) and 176.0 (s); vmax(neat)/cm21 1714 1530 1496 1372 790 762 700 and 666 [Found MH+ (FAB) 433.1674.C26H26N2O2Cl (MH+) requires 433.1683]. References 1 (a) J. Cornelisse Chem. Rev. 1993 93 615; (b) P. A. Wender L.Shiggel and J. M. Nuss Org. Photochem. 1989 10 357; (c) P. J. Wagner Acc. Chem. Res. 1989 22 83; (d ) H. Aoyama Y. Arata and Y. Omote J. Chem. Soc. Chem. Commun. 1990 736; (e) N. Al-Jalel and A. Gilbert Recl. Trav. Chim. Pays-Bas 1990 109 21; (f ) P. A. Wender and M. A. deLong Tetrahedron Lett. 1990 31 5429; (g) A. Gilbert and P. W. Rodwell J. Chem. Soc. Perkin Trans. 1 1990 932; (h) D. Bryce-Smith and A. Gilbert Tetrahedron 1977 33 2459; (i) D. Bryce-Smith A. Gilbert B. H. Orger and H. M. Tyrrell J. Chem. Soc. Chem. Commun. 1974 334; (j) D. Bryce-Smith B. Foulger J. Forrester A. Gilbert B. H. Orger and H. M. Tyrrell J. Chem. Soc. Perkin Trans. 1 1980 55; (k) A. Gilbert G. N. Taylor and M. W. bin Samsudin J. Chem. Soc. Perkin Trans. 1 1980 869; (l) J. Mattay H. Leismann and H. D. Scharf Chem.Ber. 1979 112 577; (m) H. G. Heine and W. Hartmann Angew. Chem. Int. Ed. Engl. 1975 14 698; (n) M. F. Mirbach M. J. Mirbach and A. Saus Tetrahedron Lett. 1977 959. 2 D. Bryce-Smith B. Foulger J. Forrester and A. Gilbert J. Chem. © Copyright 1997 by the Royal Society of Chemistry Soc. Chem. Commun. 1972 664; J. C. Berridge J. Forrester B. Foulger and A. Gilbert J. Chem. Soc. Perkin Trans. 1 1980 2425. 3 A. Gilbert and P. W. Rodwell J. Chem. Soc. Perkin Trans. 1 1990 931. 4 H. D. Scharf H. Leismann W. Erb and J. Aretz Pure Appl. Chem. 1975 41 581. 5 G. O. Schenck J. Kuhls and C. H. Krauch Justus Liebigs Ann. Chem. 1966 693 20; K. Kraft G. Koltzenburg and G. O. Schenck Tetrahedron Lett. 1965 353; T. S. Cantrell J. Org. Chem. 1974 39 3063. 6 The MM2 force field in Chem3D (Cambridge Soft Co.) was used for the calculation.Cf. U. Bunkert and N. L. Allinger Molecular Mechanics ACS Washington DC USA 1982; J. W. Ponder J. Comput. Chem. in preparation. 7 D. Bryce-Smith and A. Gilvert Tetrahedron 1976 32 1309. 8 G. Himbert K. Kiehl and G. Maas J. Chem. Soc. Chem. Commun. 1984 900; L. A. M. Turkenburg P. M. L. Blok W. H. De Wolf and F. Bickelhaupt Angew. Chem. Int. Ed. Engl. 1982 21 298; A. F. Murad J. Kleinschroth and H. Hopf Angew. Chem. Int. Ed. Engl. 1980 19 389. 9 M. Wollenweber H. Fritz G. Rihs and H. Prinzbach Chem. Ber. 1991 124 2465; M. Mintas D. I. Schuster and P. G. Willard Tetrahedron 1988 44 6001. 10 J. Bregmen K. Osaki G. M. J. Schmidt and F. I. Sontag J. Chem. Soc. 1964 2021. 11 W. M. Hardham and G. S. Hammond J. Am. Chem. Soc. 1967 89 3200. 12 S.Kohmoto T. Kreher Y. Miyaji M. Yamamoto and K. Yamada J. Org. Chem. 1992 57 3490. 13 J. S. Bradshaw J. Org. Chem. 1966 31 3974. 14 T. S. Lee S. J. Lee and S. C. Shim J. Org. Chem. 1990 55 4544. Paper 6/01710J Received 11th March 1996 Accepted 19th August 1996
ISSN:1472-7781
DOI:10.1039/a601710j
出版商:RSC
年代:1997
数据来源: RSC
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