摘要:
J. CHEM. SOC. PERKIN TRANS. 1 1994 Asymmetric Diels-Alder React ion of 0pt ica IIy Active a-(2-exo-Hydroxy-10-bornyl)sulf inylmaleimides and its Application to Optically Active 5-Fu nct i on a Ii sed Pyr ro Ii n es via Ret ro -DieIs-A Id e r React ion Yoshitsugu Arai,a Makoto Matsui,a Akihito Fujii,a Tohru Kontani,a Toshiyuki Ohno,a Toru Koizumi"sa and Motoo Shirob a Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, Sugitani 2630, To yama 930-0 1, Japan Rigaku Corporation, 3-9-12 Matsubara, Akishima, Tokyo 196, Japan Optically pure sulfinylmaleimides 1 have been synthesized. The Diels-Alder reactions of the sulfoxides 1 with various dienes showed high diastereoselectivity. Regioselective reduction of the adducts 4c and 6c followed by desulfinylation afforded the y-hydroxy lactams 17 and 27, respectively. N-Acyliminium additions using compounds 17 and 27 proceeded diastereoselectively to give y-alkyl lactams 23 and 29 by virtue of its conformationally rigid, bicyclo[2.2.1] -and 7-oxabicyclo[2.2.1] -heptene moiety, respectively. The use of compound 29 allows a simple preparation of chirally 5-functionalised A3-pyrrolin-2-ones of high optical purity such as compound 25 via retro- Diels-Alder reaction, whereas the thermal cycloreversion of adduct 23 required such forcing conditions as flash vacuum pyrolysis.Despite a large number of highly asymmetric Diels-Alder reactions * that have been exploited, most of the dienophiles in the cycloadditions have been treated with reactive Diels-Alder dienes such as cyclopentadiene, but are generally unreactive towards furan under conventional conditions due to its aromaticity. Thus, development of the Diels-Alder reaction with low-reactivity dienes still remains elusive.During the course of our studies on asymmetric Diels-Alder reactions using a chiral vinyl sulfoxide as a dienophile,'" we focused on the utility of chiral sulfinylmaleimides. Since maleimides are quite reactive towards a variety of Diels-Alder dienes,2 the use of chirally functionalised maleimides seemed to be attractive from the viewpoint of the enhancement of dienophilic reactivity as well as the diastereoselectivity in asymmetric Diels-Alder cycloadditions. To date, some reports of Diels-Alder cyclo- additions using maleimides and chiral diene partners and involving chirally N-substituted maleimides have appeared.However, an efficient route to maleimides bearing a chiral auxiliary in the a-position is as yet unknown. We here describe the syntheses and Diels-Alder reaction of a series of chiral a-sulfinylmaleimides 1 having a (2-exo-hydroxy- 10-borny1)- sulfinyl group as a chiral auxiliary, in detail.5 Results and Discussion Preparation of a-SulJinylma1eimide.s.-The first task was to prepare the chiral N-substituted maleimides 1which would be readily obtained according to our procedure of preparing diastereoisomerically pure 2-exo-hydroxy- 1 0-bornyl sulfoxides reported previously.6 The addition of 10-mercaptoisoborneol to N-methylmaleimide in the presence of a catalytic amount of triethylamine gave the succinimide 2a as a 1 :1-mixture of diastereoisomers (Scheme 1).Heating of compound 2a with N- chlorosuccinimide (NCS) at reflux in carbon tetrachloride led to the maleimide 3a with spontaneous dehydrochlorination during the heating. Exposure of compound 3a to rn-chloro- perbenzoic acid (MCPBA) afforded the sulfinylmaleimide la as essentially a single diastereoisomer in quantitative yield. The high diastereoselectivity in the oxidation and the expected absolute stereochemistry at the sulfur centre could be explained by analogy with our earlier synthesis6 of chiral 2-exo-hydroxy-10-bornyl sulfoxides. Other sulfinylmaleimides 1b-e were also prepared in excellent yield by the same procedure, and the absolute stereochemistry of sulfoxides 1 could be assigned as R,.t Sulfinylmaleimide If was prepared by a Mitsunobu reaction of sulfide 3g and but-3-yn-1-01 followed by oxidation of the resulting sulfide 3f. All attempts to oxidise sulfide 3g to sulfoxide lg were unsuccessful, resulting in polymerisation of starting material.Although the maleimides 1 obtained are sensitive to acid, base or silica gel, the crude oxidation products from sulfides 3 are essentially pure enough to be used for the cycloaddition. Diels-A lder Reaction of cr-SulJinylmaleimides. -At the outset , the Diels-Alder reaction of maleimides 1 with cyclopentadiene, which is very reactive, were examined and the results are summarised in Table 1.As one can see, in the absence of a Lewis acid (ZnCl,), the cycloaddition of maleimides 1 affords two adducts 4 and 5 with moderate diastereoselectivity. Whatever substituents are incorporated onto the nitrogen atom of maleimides 1, the Diels-Alder reaction of a dienophile 1 with cyclopentadiene in the presence of a Lewis acid proceeds with a high degree of diastereoselectivity to give an adduct 4, along with a small amount of the corresponding stereoisomer 5, almost exclu- sively. No other diastereoisomeric adducts (i. e. exo-imido-carbonyl adducts) were detected in the reaction products. These two endo-adducts 4 and 5 are generally inseparable without the aid of HPLC; however, simple recrystallisation of the original mixture affords isomerically pure stereoisomers 4 in good yield.The adducts 4d and 5d were sensitive to silica gel, leading readily to the unsubstituted parent 4g and 5g, respectively. The product ratio of the adducts 4d and 5d was thus determined by the 'H NMR spectrum of compounds 4g and 5g derived by hydrolytic cleavage of the tert-butyldimethylsilyl group by exposure to silica gel. The minor adducts 5a and 5e derived from the reaction of dienophiles la and le were isolated by preparative TLC (PLC) (after 30 developments) and fully characterised. t The symbol R, in this text expresses the absolute configuration of the sulfinyl centre as R. 26 J. CHEM. SOC. PERKIN TRANS. I 1994 0 @OH + Q4 -iisqN-R' @OH 0 0 2 a R'=Me b R1 = Ph C R' = CH2Ph d R' = SiMe2Bu' iii -@OH qN8 R' = CH2C6H40Me-g f R' = CH2CH&rCH -R' g R'=H 0 0 1 3 Scheme 1 Reagents and conditions: i, Et,N (cat.), CH,Cl,; ii, N-chlorosuccinimide, CCl,; iii, rn-chloroperbenzoic acid, CH,Cl, Table 1 Diels-Alder reaction of maleimides 1with cyclopentadiene Reaction conditions 4:5 Additive Entry 1 Time (t/h) Temp.(T/OC) (1.5 mol equiv.) (Product ratio) Isolated yield 1 la 0.5 0 4a:5a (27 :73)" 99 2 la 0.5 0 ZnCl, 4a:5a (94:6)" 95 3 lb 0.5 0 4b:5b (28:72)" 98 4 lb 0.5 0 ZnC1, 4b:5b (90: 10)" 97 5 lc 0.5 0 4c:5c (28:72)" 97 6 lc 1 0 ZnC1, 4c:5c (97:3)" -100 7 Id 0.5 -78 ZnC1, 4d :5d (99.5 :0.5) 93 8 le 0.5 0 4e:5e (30:70)" 97 9 le 0.5 0 ZnC1, &:5e (98:2)" 98 10 If 0.5 -75 ZnC1, 4f: 5f (98 :2) 93 " The ratio was determined from the pertinent peaks in the 'H NMR spectrum.The ratio was estimated by HPLC analysis (see Experimental section). 'Total yield of both diastereoisomers. 10 4 5 by transformation of the resulting compound 4g into the benzyl The endo stereochemistry of adducts 4 and 5 was evident derivative 4c under Mitsunobu conditions. from the coupling contants (J 34 Hz) between 6-H and 7-H Under the chelation-controlled (ZnC1,) conditions, the high (bridgehead) in the 'H NMR spectra. The absolute stereo- diastereoselectivity in the cycloaddition can be easily explained as shown in Fig. 2. Inchemistry of adducts 4 was determined on the basis of single- by the mechanism reported previo~sly,~ crystal X-ray analysis of compound 4c (Fig.l).* The atomic the presence of a Lewis acid, the dienophile 1 would exist co-ordinates, bond lengths and bond angles have been predominantly as the more stable conformer A which reacts deposited with the CCDC.? The absolute stereochemistry of with cyclopentadiene from the less hindered lone-pair side, to compound 4d was also established by protodesilylation followed give the adduct 4. Without a Lewis acid, however, a more stable conformer B, due to the dipole-dipole repulsion, would react * Since theabsolute stereochemistry ofthe bornyl moiety in compound 4c from the sterically less hindered face, to give the adduct 5 is known, all other asymmetric centres are automatically established by predominantly. X-ray analysis.To date, we have devised several chiral sulfinyl dienophiles t Supplementary data: see Instructions for Authors, in the January issue. that give high diastereoselectivity in cycloadditions with cyclo- J. CHEM. SOC. PERKIN TRANS. 1 1994 Table 2 Diels-Alder reaction of maleimides 1 with other dienes Reaction conditions' Additive Entry 1 Diene Time (t/h) Temp. (T/OC) (1.5 mol equiv.) 1 lc furan 62 -20 2 lc furan 0.5 0 ZnC1, 3 lc furan 60 0 ZnCl, 4 Ic furan 1 10 ZnC1, 5 lc furan 56 10 ZnCl, 6 lc furan 10 20 ZnC1, 7 lc furan 24 0 8 lc furan 5 25 9 le furan 0.5 0 ZnCl, 10 Ic cyclohexa- 1,3-diene 1 -40 ZnC1, 11 Ic cyclohexa- 1,3-diene 10 25 12 Ic anthracene 18 -20 ZnC1, 13 Ic anthracene 4 80 Product (ratio) Yield (%)d 6c:7c:&:9c(49:26: 10: 15)b 60 666c:7c(71 :29)b 726c:7~(68:32)~ 566c:7c:&:9c (79: 9: 7: 5)h 686c:7c:&:9c (80:8 :4:8) 566c:& (55:45)b 566c:7c:&:9c (29:22:29:20) 546c:7c:&:9c (22 :32 :24:22) 766e :7e (73 :27) 7210:11 (-100:O)b1O:ll (22:78)b 70 12:13(-1OO:O)' 96 12:13(56:M)' 77 'The reactions were conducted in methylene dichloride as solvent except for entry 13 (benzene as solvent).HPLC analysis. 'The ratio was determined by integration of the pertinent peaks in the 'H NMR spectrum. Total yield of diastereoisomers. Fig. 1 X-Ray molecular structure of compound 4c I II "t tB I Fig. 2 pentadiene.Among the dienophiles investigated so far, only (2-pyridylsulfiny1)acrylates'react with furan to afford Diels- Alder adducts. However, the reactions required long reaction times and suffered from low yields. In order to investigate the dienophilic reactivity and the diastereoselectivity of the sulfinyl maleimides 1 with several poorly reactive dienes including furan, we chose N-benzyl derivative lc since it was found that the diastereoselectivity of the reaction does not depend upon the N-substituent on the dienophile. For the cycloaddition of compound lc with furan, notable reactivity as well as diastereoselectivity was apparent. The results are listed in Table 2. With lower reaction temperature (entry 1) the reaction afforded all four possible adducts 6c-9c, while the reaction conducted at 0 "C (entries 2 and 3) gave only two adducts, 6c and 7c.On the other hand at higher temperature (10 "C), the exo adduct 6c was formed pre- dominantly, together with small amounts of other adducts 7c-9c. At room temperature (entry 6) the reaction afforded two exo adducts 6cand & in roughly a 1:1 mixture. These results show that the initially formed mixture of endo adducts 7c and 9c undergoes thermal isomerisation, with reversion to starting materials followed by recombination. It was found that under the specified conditions (entries 4 and 5) high diastereoselectivity (6cus. &) as well as high stereoselectivity ((6c + &) us. (7c + 9c)} was realized. 6 7 8 N-R' N-CHzPh 0 0 9 10 11 12 13 The adducts 6c4k were isolated and fully characterised; however, the adduct 9c was inseparable from other products by column chromatography.The endo stereochemistry of adducts 7c and 9c was readily assigned based upon the presence of coupling between 6-H and the bridgehead 7-H (J -5 Hz) in 28 C Fig. 3 X-Ray molecular structure of compound 6c the 'H NMR spectra. The ex0 stereochemistry of adducts 6c and &was assigned on the basis of the lack of coupling between 6-H and the bridgehead 7-H in the 'H NMR spectra. The absolute stereochemistry of adduct 6cwas established by single- crystal X-ray analysis, shown in Fig. 3. Atomic coordinates, bond lengths and angles have been deposited with the CCDC.Diels-Alder reaction of dienophile lc with cyclohexa- 1,3- diene and anthracene in the presence of ZnCl, proceeded smoothly to give the adducts 10 and 12 as single products, respectively. Without a Lewis acid these reactions were slow even at 80 "C and gave a mixture of two adducts (i.e. 10 and 11 or 12 and 13) in each case. The stereochemistry of adducts 10-13 was tentatively assigned on the basis of the reaction mechanism described above. Simple Entry to Chiral y-Hydroxy Lacturns.-Having obtained the Diels-Alder adducts in the cycloaddition of dienophile 1, attention was then turned to their transformation into a chiral, y-hydroxy lactam. The utility of y-hydroxy lactams as useful precursors for the synthesis of a number of alkaloids through N-acylimino addition has been well docu- mented to date.8 The use of a chiral y-hydroxy lactam would thus allow a convenient, enantioselective synthesis of the alkaloids.To obtain the chiral y-hydroxy lactam, two routes can be envisaged: (i) via asymmetric reduction of a meso-imide (route a), and (ii) by diastereoselective reduction of one of the imidocarbonyl groups in a chiral imide (route b, e.g. 4)." J. CHEM. SOC. PERKIN TRANS. 1 1994 In spite of the pioneering work by Mukaiyama et al.,9a the former method often provides unsatisfactory results. Our approach relies on the latter route, which effects an easy access to chiral hydroxy lactams from the Diels-Alder adduct. Reduction of adduct 4cwith NaBH, in refluxing ethanol was complete with 2 h, and led to the y-hydroxy lactam 14 as a single product in 93% yield (Scheme 2). The method of Speckamp and co-workers ' ' through acid-catalysed NaBH, reduction of imides did not work well for the imide 4c,resulting in recovery of a substantial amount of starting material.The regiochemistry of the hydroxy group of the reduction product could not be ascertained at this stage. Desulfinylation of compound 14 with SmI,12 proceeded smoothly to give the hydroxy lactam 15 in 60% yield, with efficient recovery of the chiral auxiliary, 10-mercaptoisoborneol and the bis-sulfide 16.' The ratio of 10-mercaptoisoborneol and bis-sulfide 16 depended upon the reaction conditions: without tert-butyl alcohol as a proton source, compound 16 was produced exclusively. The ethoxy lactam 17 was obtained by treatment of the alcohol 15 with EtOH and pyridinium toluene-p-sulfonate (PPTS).l4 Alternatively, treatment of compound 6c with NaBH, followed by acidic work-up '' afforded the hydroxy lactam 18 as a single product in 94%yield (Scheme 3).On the other hand reduction of compound 6cwith NaBH,/H+ and basic work-up gave its epimeric lactam 19 exclusively in 92%yield. Treatment of compound 19 with NaOEt or a catalytic amount of HCl resulted in complete epimerisation into compound 18. It was thus found that epimer 18 is the thermodynamically more stable lactam. The regiochemistry of the hydroxy group in compounds 18 and 19 was now established based upon the coupling of 5-H with 6-H in the 'H NMR spectra.The 5-H proton of compound 18 appears as a doublet (J 6.6 Hz) by coupling with OH at 6 5.00, whereas that of epimer 19 exhibits as a doublet by coupling with 6-H (J 7 Hz). Desulfinylation of sulfoxides 18 and 19 with samarium(I1) iodide afforded the lactams 20 and 21, respectively. The sulfinyl group, which has served as a chiral auxiliary in the Diels-Alder cycloaddition, was thus employed as an efficient control element to effect the diastereoselective reduc- tion of the imidocarbonyl group in the adducts. Next, we undertook the N-acyliminoaddition to the hydroxy lactams. N-Acyliminoaddition to y-Hydroxy Lactams.-For the N-acyliminium addition, racemic ( f)-17 and the sulfonyl derivative ( f)-22 were employed as substrates.Using organo- metallic compounds such as organic cuprate '' and allyl- silane,' we examined the alkylation of the ethoxy compound ( f)-l7, and results are summarised in Table 3. The reaction of compound ( f)-17 with allyltrimethylsilane (4 mol equiv.) b -HO 4c 14 RSSR + RSH 15 R~=H 17 R2= Et iiic 16 Scheme 2 Reagents and conditions: i, NaBH,, EtOH; ii, SmI,, HMPA, Bu'OH, THF; iii, PPTS, EtOH J. CHEM. SOC. PERKIN TRANS. 1 1994 Table 3 N-Acyliminoaddition with organometallic reagents Lewis acid ( k )-23, Isolated Entry Nucleophile (mol equiv.) (mol equiv.) Solvent Temp. (T/"C) Time (t/h) R2= yield (%) 1 ( f)-I7 2 ( f)-I7 3 ( f)-17 4 ( f)-I7 5 ( f)-I7 6 ( f)-I7 7 ( f)-17 8 ( ? )-I7 9 ( f)-I7 10 ( f)-I7 1 1 ( k )-I7 12 (+)-I7 13 ( f)-22 allyltrimethylsilane, 4 SnCl,, 2.5 CHzC1, -78-25 22 CH,CH=CH, 45" allyltrimethylsilane, 4 TiCl,, 2.5 CH2C12 -78 6.5 CH,CH=CH, 44" allyltrimethylsilane, 4 TiCl,, 2.5 CH2C12 0 1 CH,CH=CH, 94 allyltrimethylsilane, 4 TiCI,, 2.5 CH,CI, 25 0.5 CH2CH=CH, 96 allyltrimethylsilane, 4 BFyEt,O, 2.5 CH,CI, 0 24 CH,CH=CH, 73' allyltrimethylsilane, 4 butylmagnesium chloride, 3 dibutylcopper lithium, 2 vinylmagnesium bromide, 3 BF3*Et20, 2.5 BF3*Et,0,2 CH,CI, THF Et20 THF 25 70 -78-5 25 -70 17.5 23 1 2 CH,CH=CH, Bu Bu CH=CH2 95 0 0 20 butylcopper, 2 vinylcopper, 2 heptylcopper 3 BFyEt,O,2 BF,*Et,O, 2 BF3*Et20, 2 Et20 Et20 Et20 -78-25 -78-25 -78 -25 2.5 2.5 3 Bu CH=CH, C7Hl5 90 65 87 heptylmagnesium bromide, 4 ZnBr,, 2 CHZCI, 0-25 14 C7H15 83 " Not purified.Yield was determined by integration of the pertinent peaks in the 'H NMR spectrum. 48% of substrate ( f)-17 was recovered. '14%of substrate ( f)-I7 was recovered. Substantial amounts of compounds ( f)-17 and ( f)-14 were detected in the reaction mixture. 0 6c OH /3" "' ~ iii &@j-CH2ph RSO 7 Hz 18 19 IN wpCH2f'h CH2Ph0 &$:-0 20 21 Scheme3 Reagents and conditions: i, NaBH,, EtOH-THF; then acidic work-up; ii, NaBH,, EtOH-THF; then basic work-up; iii, EtONa, EtOH or conc. HCI (cat.), THF; iv, SmI,, Bu'OH, HMPA, THF in the presence of TiC1, (2.5 mol equiv.) proceeded smoothly to give the allylated lactam ( f )-23 (R2 = allyl) in excellent yields (entries 3 and 4).It was found that other Lewis acids such as BF,*Et,O or SnCl, were less effecti~e.'~ Similarly the cuprate/BF,-mediated alkylations (entries 10-1 2) afforded the corresponding lactams ( f )-23,whereas the addition of a Grignard reagent or a dialkylcuprate to compound ( k )-17 was inefficient (entries 7-9). For the reaction of compound ( f )-17 the use of a lower amount of the nucleophile and a Lewis acid decreased the yields. The reaction of a Grignard reagent with the sulfonyl lactam 22, which was obtained from the ethoxy analogue ( f )-17 by the procedure developed by Ley and co- workers,18 produced the alkylated lactam in 83% yield. In contrast to the reaction of the ethoxy lactam using an organo- copper reagent, the route uia a sulfonyl lactam was found to be convenient from the viewpoint of easy handling and simple operation techniques.In all cases the reactions proceed with high diastereo- selectivity to give the corresponding lactams ( f )-23as a single diastereoisomer. The stereochemistry of the newly formed C(5) asymmetric centre could be tentatively assigned as shown because the nucleophilic attack should take place from the sterically less hindered convex face of the bicycloC2.2. llheptene group. The stereochemical assignment of the products 23 was unequivocally established by transformation of (+)-23 (R2 = C7H15) into a chiral pyrrolidin-Zone 24'" with known absolute configuration (uide infra).(LN-CH2PhR2 C7H15 C7H15 22 R2 = S02T0l-p 25 24 X=O 23 R2 = alkyl, allyl, aryl 30 X=S 26 X = S(O)R, Y = OEt; 27 X = H, Y = OEt 3128 X = H, Y = S0,ToI-p; 29 X= H, Y =C,H15 In a similar manner to its racemate (?)-23 (R2 = C7H15), the optically active heptyl lactam (+)-23(R2 = C7H15) {CCC]~~+ 24.7 (c 2.1, CHCL,)} was obtained from the sulfonyl lactam (+)-22 {[a]i4 +29.4 (c 1.97, CHCl,) -100%e.e. judged by chiral HPLC analysis}. The optical purity of (+)-23 (R2 = C7H15) could not be determined by chiral HPLC analysis because of unsatisfactory resolution; however, there is no doubt about the high optical purity of compound (+)-23 (R2= C7H15) since it was obtained as a single diastereoisomer from optically pure sulfone ( + )-22.Although a retro-Diels-Alder reaction of compound (+)-23 (R2 = C7HI5) by heating in a high b.p.solvent such as toluene or o-dichlorobenzene did not work, flash vacuum pyrolysis 2o (FVP, 450 OC, 0.5 Pa) effecting thermal cycloreversion afforded the 5-heptylpyrrolin-Zone 25 {Cali8 +42.4 (c 2, CHCl,)} in 78% yield. The enantiomeric excess (e.e.) was 74% by HPLC analysis using a chiral column. Hydrogenation of compound 25 over pt on alumina at 3.5 atm for 5 h gave the known compound 24 {Calk6 -13.3 (c 1.2, CH2C12); lit., '9[a]ho -21.9 (c 1.0, CH2C12)}. Our synthetic lactam 24 indicates 57-61 % optical purity when compared with the evaluated optimum rotation value for 2 94% e.e. Presum- ably the pyrroline 25 obtained with moderate e.e., under the FVP conditions, racemised because A3-pyrrolin-2-ones tend to undergo thermal interconversion ' into the corresponding A4-pyrrolin-2-ones at ambient or higher temperature. Other catalysts such as Pd/C and/or longer reaction period resulted in racemisation 22 of lactam 24.The absolute stereochemistry of lactam 24 prepared above was established as S by comparison with the sign of the reported value l9 of the optical rotation.To overcome the unsatisfactory enantiomeric control, we envisaged the use of a 7-oxabicyclo[2.2. llheptene moiety that would easily effect cycloreversion under milder conditions. Attempts at ethoxylation of hydroxy lactam 20 or 21 under conditions using EtOH-H 'or EtOH-PPTS met with failure. On the other hand reduction of compound 6c followed by treatment by acid proceeded smoothly to give the ethoxy lactam 26, which was desulfinylated with SmI, to give the lactam 27.After sulfonylation of ethoxy lactam 27 the resulting sulfone 28 was subjected to acylimino addition with heptyl- magnesium bromide to afford the heptyl derivative 29. The cycloreversion of adduct 29 conducted in liquid phase (xylenes, reflux, 0.5 h) led to the A3-pyrrolin-2-one 25 {[a]?+ 58.8 (c 0.8, CHCl,)} of high optical purity (297% e.e. judged from chiral HPLC analysis). Hydrogenation of compound 25 over 5% Pt/alumina (tert-butyl alcohol, 3.5 atm, 2 h) and subsequent treatment of optically active lactam 24 { Cali6 -19.3 (c 0.5, CH,Cl,} with 2,4-bis-(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson's reagent) pro- duced a thiolactam 30 {[a]h6 -145.5 (c 0.44, EtOH), 293% e.e.by chiral HPLC analysis} whose spectroscopic data were identical with those {[a];' -107.1 (c 1.3, EtOH)} reported previously.' Thiolactam 30 has been further transformed into cis-2-butyl-5-heptylpyrrolidine 31 ' that is of some interest because of its entomological properties,,, as well as its trans- isomer.24 Furthermore, 5-substituted A3-pyrrolin-2-ones are widely utilised not only as Diels-Alder dienophiles 25 but also as potent intermediates 26 for alkaloids synthesis. In conclusion, maleimide dienophiles having a (2-exo-hydroxy- 10-borny1)sulfinyl group as a chiral auxiliary show high diastereoselectivity in Diels-Alder reactions under chela- tion-controlled conditions.The Lewis acid (ZnC1,) as an additive plays a role not only as a reaction promoter but also as a chelating agent of the sulfinyl oxygen with one imidocarbonyl group, resulting in a rigid Diels-Alder transition state of the dienophile. High stereocontrol in the N-acyliminium addition directed by a bicyclo[2.2.1]- and a 7-oxabicyclo[2.2.l]-heptene moiety has been achieved. RetrwDiels-Alder reaction of the resulting 7-oxabicycloC2.2. llheptene system proceeded smoothly to give a chirally 5-substituted A3-pyrrolin-2-one. Experimental M.p.s were determined with a Yanagimoto micro melting-point apparatus and are uncorrected. B.p.s for Kugelrohr distillation indicate bath temperature. IR spectra were recorded on a Perkin-Elmer 1605 spectrometer. NMR spectra were measured in CDCl,, unless otherwise stated, with tetramethylsilane as internal standard on a JEOL GX-270 (270 MHz 'H) and a Varian XL-200 (50.1 MHz 13C) spectrometer.J Values are in Hz. Mass spectra were recorded on a JEOL JMS-300 spectrometer. Optical rotations were recorded on a JASCO DIP-140 digital polarimeter, and are given in units of lo-' deg cm2g-' . TLC analyses were performed using Merck pre-coated silica 60F254 plates (0.2 mm). Column chromatography was carried out on Merck silica (70-230 mesh) or Merck silica (230- 400 mesh). Dry tetrahydrofuran (THF) was freshly distilled from sodium benzophenone ketyl prior to use. The organic extracts were dried over anhydrous magnesium sulfate which was later removed by filtration.The solvent used was con- J. CHEM. SOC. PERKIN TRANS. I 1994 centrated by a rotatory evaporator under reduced pressure. Dry methylene dichloride was distilled from phosphorus pentaoxide and stored with 4 8, molecular sieves. MCPBA was used after purification by washing with phosphate buffer of pH 7.5 according to the literature method.27 Zinc chloride and zinc bromide were dried at 160 "C in an oven for 2 h prior to use. High-performance liquid chromatography (HPLC) was per- formed on a 5 p Develosil 60 column (4.6 mm x 250 mm). Chiral HPLC analyses were performed using a chiral column (Daicel Chemical Industries Ltd.), Chiralcel OC or Chiralpak AS (4.6 x 250 mm). Peak ratios on HPLC were determined with an integrator (Shimadzu Chromatopac C-R3A).Light petroleum refers to the fraction boiling in the range 40-60 "C. General Procedure for Preparation of 2-(2-exo-Hydroxy- 10- b0rn~lthio)succjnimides2.-To a solution of the parent N-substituted maleimide (0.16 mmol) in methylene dichloride (30 cm3) at 0 "C was added a solution of 10-mercaptoisoborneol (3.0 g, 0.16 mmol) in methylene dichloride (10 cm3) followed by 4 drops of triethylamine. The mixture was allowed to reach 25 "C and was stirred for a further 4-12 h. The resulting mixture was concentrated under reduced pressure and the residue was chromatographed on silica with hexane-ethyl acetate (4 : 1) to give the corresponding compound 2 as a diastereoisomeric mixture.a-({( 1S,2R,4R)-2-Hydroxy-7,7-dimethylbicycfo[2.2.llheptan-1-yl }methylthio)-N-methylsuccinimide2a. Prepared from N-methylmaleimide (500 mg, 4.5 mmol) and 1O-mercaptoiso-borneol(880 mg, 4.73 mmol) in 89% yield. Apowder, m.p.s 105- 107 and 120-130°C (from hexanexthy1 acetate) (Found: C, 60.9; H, 7.8; N, 4.9. C,,H,,NO,S requires C, 60.59; H, 7.80; N, 4.71%); Calk5 -20.5 (c 1.0, CHCl,); v,,,(KBr)/cm-' 3570,2950, 1690, 1435 and 1275; 6, 0.85 (3 H, s, Me), 1.05 and 1.09 (total 3 H, each s, diastereoisomeric Me), 1.0-1.9 (7 H, m, bornyl H), 2.55 and 2.60 (total 1 H, each dd, J 19 and 4.5, and 19 and 4, 4-H), 2.66 and 3.03 (total 1 H, br, OH), 2.83 and 2.96 (total 1 H, each d, J 11, 10'-Ha) 3.02 and 3.04 (total 3 H, s, NMe), 2.90 and 3.19 (total 1 H, each d, J 1 1, 10'-Hb), 3.17 and 3.19 (total 1 H, each dd, J 19 and 9, 4-H), 3.74 and 3.81 (total 1 H, each dd, J 9 and 4.5, 3-H) and 3.90 (1 H, m, 2'-H); m/z 297 (M'), 279,184, 145 and 108.a({( 1 S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2.2.l]heptan-l-yl}methylthio)-N-phenylsuccinimide 2b. Prepared from N-phenylmaleimide (500 mg, 2.89 mmol) and 1O-mercaptoiso-borneol(564 mg, 3.03 mmol) in 98% yield. A powder, as a 1 : 1 diastereoisomeric mixture, m.p. 86-89 "C (from hexane-ethyl acetate) (Found: C, 67.1; H, 7.0; N, 4.0. C2,H2,N0,S requires C, 66.83; H, 7.01; N, 3.90%); [a]k5 -22.4 (c 1.0, CHCI,); v,,,(KBr)/cm-' 2950, 1710, 1500, 1380, 1180 and 850; BH 0.84 and 0.86 (total 3 H, each s, diastereoisomeric Me), 1.06 and 1.07 (total 3 H, each s, Me), 1.O-1.9 (7 H, m, bornyl H), 2.63.4 (5 H, m, 4- and 10'-H,, and OH), 3.8-4.0 (2 H, m, 3- and 2'-H) and 7.2-7.6 (5 H, m, ArH); m/z 360 (M' + l), 359 (M'), 208,206 and 175.N-Benzyl-a-({(1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo-C2.2. llheptan- 1-yl}methylthio)succinimide 2c. Prepared from N-benzylmaleimide28 (1 1.3 g, 60 mmol) and 10-mercaptoiso- borneol (1 1.5 g, 62 mmol) in 96% yield. An oily 1 : 1 dia-stereoisomeric mixture (Found: M', 373.1696. C,,H,,NO,S requires M, 373.1710); v,,,(neat)/cm-' 2950, 1700, 1395 and 1165;dH0.80 and 0.8 1 (total 3 H, each s, diastereoisomeric Me), 0.99 and 1.05 (total 3 H, each s, Me), 0.9-1.9 (7 H, m, bornyl H), 2.55 and 2.60 (total 1 H, each dd, J 19 and 4.5, 4-Ha), 2.74 and 2.89 (total 1 H, each d, J 11, 10'-Ha), 2.78 and 3.13 (total 1 H, each d, J 11, 10'-Hb), 2.65 and 2.95 (total 1 H, each d, J 3, OH), 3.14 and 3.18 (total 1 H, each dd, J 19 and 9, 4-Hb), 3.70 and 3.79 (total 1 H, each dd, J 9 and 4.5, 3-H), 3.87 (1 H, m, 2'-H), 4.63 and 4.64 (total 1 H, each d, J 14 and 13, NCHH), 4.70 and J.CHEM. SOC. PERKIN TRANS. 1 1994 4.73 (total 1 H, each dd, J 14 and 13, NCHH) and 7.2-7.4 (5 H, m, ArH); m/z 373 (M'), 355,222, 188 and 91. N-(tert-Butyldimethylsily1)-a-({(1 S,2R,4R)-2-hydroxy-7,7- dimethylbicyclo[2.2.1 Iheptan- 1-yl }methylthio)succinimide 2d. Prepared from N-( tert-butyldimethylsily1)maleimide29 (596 mg, 2.8 mmol) and 10-mercaptoisoborneol(500mg, 2.7 mmol) in 99% yield.An oily 2: 1 diastereoisomeric mixture (Found: M', 397.2072. C,,H,,NO,SiS requires M, 397.2105; Cali6 -19.8 (c 4.9, CHCl,); v,,,(neat)/cm-' 3500, 2950, 1700, 1470, 1320 and 1170; 6, 0.35 (6 H, s, SiMe,), 0.76 (2/3 x 3 H, s, diastereoisomeric Me), 0.83 (1/3 x 3 H, s, diastereoisomeric Me), 0.87 (9 H, s, SiBu'), 0.95 (1/3 x 3 H, s, Me), 0.99 (2/3 x 3 H, s, Me), 0.8-1.2 (2 H, m, bornyl H), 1.4-1.8 (5 H, m, bornyl H), 2.46 (2/3 x 1 H, dd, J 19, 5, X of AMX pattern), 2.50 (1/3 x 1 H, dd, J 19 and 4, X of AMX pattern), 2.62 (1/3 x 1 H, d, J 11.4, 10'-Ha), 2.74 (1/3 x 1 H, d, J 11.4, 10'-Hb), 2.85 (2/3 x 1 H, d, J 11.2, 10'-Ha), 3.03 (2/3 x 1 H, d, J 11.2, 10'- Hb), 3.0-3.15 (1 H, m, M of AMX pattern), 3.2 (1 H, br, OH), 3.61 (2/3 x 1 H, dd, J 9.6 and 5, A of AMX pattern), 3.69 (1/3 x 1 H, dd, J 9.5 and 4, A of AMX pattern) and 3.8 (1 H, br, 2'-H); mjz 398 (M' + l), 397 (M'), 380,340,322,246, 188 and 135.a-( ((1S,2R,4R)-2-Hydroxy-7,7-dimethylbicycl0[2.2.1Iheptan-I-yl}methylthio)-N-(4-methoxybenzyf)succinimide2e. Prepared from N-(4-methoxybenzyl)maleimide28 (34.3 g, 0.16 mol) and 10-mercaptoisoborneol (30.0 g, 0.16 mmol) in 99% yield. An oily 1 :1 diastereoisomeric mixture (Found: M', 403.1776. C,,H,,NO,S requires M, 403.1816); [a]h6 -15.5 (c 6.2, CHCI,); v,,,(neat)/cm-' 3507, 2952, 2836, 1694 and 1613; 6, 0.80 (3 H, s, Me), 0.97 and 1.05 (total 3 H, each s, dia-stereoisomeric Me), l .O-1.9 (7 H, m, bornyl H), 2.5-2.75 (3 H, m), 3.1-3.2 (2 H, m), 3.75 and 3.76 (total 3 H, each s, OMe), 3.65-3.95 (2 H, m), 4.60 and 4.64 (total 2 H, each ABq, J 14, NCH,), 6.81 (2 H, d, J 8.6, ArH) and 7.32 (2 H, d, J 8.6, ArH); m/z 403 (M'), 386,251 and 218.a( {(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.llheptan-1-yl}methylthio)succinimide2g. Prepared from maleimide (300 mg, 3.09 mmol) and 10-mercaptoisoborneol (604 mg, 3.25 mmol) in 98% yield. A powdery 1 :1 diastereoisomeric mixture, m.p. 102-105 "C (from hexane-thy1 acetate) (Found: C, 59.55; H, 7.6; N, 4.9. C,,H,,NO,S requires C, 59.35; H, 7.47; N, 4.94%); v,,,(KBr)/cm-' 3500,2950, 1775, 1705, 1350 and 1190; 6, 0.85 (3 H, s, Me), 1.05 and 1.07 (total 3 H, each s, diastereoisomeric Me), 1.&I .9 (7 H, m, bornyl H), 2.60 and 2.65 (total 1 H, each dd, J 19 and 5, and 19 and 4, 4-Ha), 2.79 and 3.08 (total 1 H, each d, J3, OH), 2.81 and 2.92 (total 1 H, each d, J 11, 10'-Ha), 2.88 and 3.16 (total 1 H, each d, J 11, 10'-Hb), 3.21 and 3.22 (total 1 H, each dd, J 19 and 9, 4-Hb), 3.78 and 3.84 (total 1 H, each dd, J9 and 5, and 9 and 4,3-H), 3.90 (1 H, m, 2'- H) and 8.80 (1 H, br, NH); m/z 283 (M'), 265, 109 and 108.General Procedure for Preparation of a-({(1S,2R,4R)-2-Hy-droxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl}methylthio)male-imides 3.-A solution of the succinimide 2 (2.5 mmol) and NCS (2.7 mmol) in carbon tetrachloride (50 cm3) was heated under reflux for 6-8 h in a well ventilated hood because of gaseous evolution of hydrogen chloride during the reaction. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure.The residue was purified by column chromatography on silica (20 g) with hexane-ethyl acetate (4: 1) to give the corresponding maleimide 3. (-)-a-( ((1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]-heptan- 1 -yl }methylthio)-N-methyfmaleimide3a. Prepared from the succinimide 2a (1.10 g, 3.7 mmol) and NCS (544 mg, 4.07 mmol) in 93% yield. Pale yellow needles, m.p. 177-178 "C (from hexane-ethyl acetate) (Found: C, 61.15; H, 7.3; N, 4.6. ClSH2,N0,S requires C, 61.00; H, 7.17; N, 4.74%); -39.7 (c 1.O, CHCl,); v,,,(CHC1,)/cm-' 1700, 1550, 1450, 1390 and975;6,0.92(3H,s,Me),l.l1(3H,s,Me),1.0-1.9(7H,m, bornyl H), 2.20 (1 H, d, J4, OH), 2.83 (1 H, d, J 1I, 10'-Ha), 3.0 1 (3H,s,NMe),3.22(1H,d,Jll,1O'-Hb),3.90(1H,dt,J7and 4,2'-H)and6.16(1 H,s,CH=);m/z295(M+), 153, 143and 108.( -)-a-( {(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]-heptan-1-yl}methylthio)-N-phenylmaleimide3b. Prepared from the succinimide 2b (800mg, 2.23 mmol) and NCS (327 mg, 2.45 mmol) in 92% yield. Pale yellow needles, 147-148 "C (from hexane-ethyl acetate) (Found: C, 67.5; H, 6.6; N, 3.8. C,,H,,NO,S requires C, 67.21; H, 6.49; N, 3.92%);[a]i6-35.7 (c 1.0, CHCl,); ~,~,(CHCl,)/crn-' 1710, 1550, 1500 and 1390; 6,0.94 (3 H, s, Me), 1.13 (3 H, s, Me), 0.8-1.9 (7 H, m, bornyl H), 1.98 (1 H, d, J6, OH), 2.89 (1 H, d, J 11, 10'-Ha), 3.29 (1 H, d, J 11, 10'-Hb), 3.91 (1 H, m, 2'-H), 6.30 (1 H, s, CH=) and 7.3-7.5 (5 H, m, ArH); m/z 357 (M+), 339,205 and 85.(-)-N-Benzyl-a-({( 1S,2R,4R)-hydroxy-7,7-dimethylbicyclo-[2.2.1]heptan-l-yl )methylthio)maleimide 3c. Prepared from the succinimide2c (4.98 g, 13.4 mmol) and NCS (1.96 g, 14.7 mmol) in carbon tetrachloride (100 cm3) in 88% yield. Yellow prisms, 133-1 34 "C (from hexane-thy1 acetate) (Found: C, 68.2; H, 6.9; N, 3.8. C2,H,,N0,SrequiresC, 67.90; H, 6.78; N, 3.77%); -31 -6 (c 1.O, CHCI,); ~,~,(CHCl,)/crn-' 1705, 1550, 1430 and 1400; 6, 0.91 (3 H, S, Me), 1.10 (3 H, S, Me), 0.8-2.0 (8 H, m, bornyl H, OH), 2.81 (1 H, d, J 11, 10'-Ha), 3.21 (1 H, d, J 11, 10'-Hb), 3.89 (1 H, dd, J 8 and 4, 2'-H) 4.66 (2 H, s, NCH,), 6.15 (1 H, s, CH=) and 7.2-7.5 (5 H, m, ArH); m/z 371 (M+), 219, 191 and91. (-)-N-(tert-Butyldimethylsily1)-a-(((1S,2R,4R)-hydroxy-7,7-dimethylbicyclo[2.2.1]heptan-1-yl }methylthio)maleimide 3d. Prepared from the succinimide 2d (1 1.4 g, 28.8 mmol) and NCS (4.23 g, 31.7 mmol) in carbon tetrachloride (200 cm3) in 55% yield.Yellow prisms, m.p. 152-1 55 "C (from hexane-ethyl acetate) (Found: C, 60.7; H, 8.3; N, 3.6. C,,H,,NO,SiS requires C, 60.72; H, 8.41; N, 3.54%); Cali6 -31.3 (c 2.0, CHCl,); v,,,(KBr)/cm-' 3452,3072,2955,2882,1757,1691 and 13 18; 6, 0.43 (6 H, s, SiMe,), 0.91 (3 H, s, Me), 0.93 (9 H, s, SiBu'), 1.11 (3 H, s, Me), 1.1-1.3 (2 H, m, bornyl H), 1.6-1.8 (5 H, m, bornyl H),2.04(1H,brs,OH),2.81(1H,d,Jll, 10'-Ha),3.19(1H,d, J 11, 10'-Hb), 3.90 (1 H, br, 2'-H) and 6.16 (1 H, s, CH=); m/z 396 (M' + l), 395 (M'), 378,362,338,320,187 and 186. (-)-a-({( 1S,2R,4R)-2-Hydroxy-7,7-dimethyfbicyclo[2.2.1]-heptan-1-yl }methylthio)-N-(4-methoxybenzyl)maleimide3e. Prepared from the succinimide 2e (30.0 g, 74.4 mmol) and NCS (10.9 g, 81.9 mmol) in carbon tetrachloride (600 cm3) in 93% yield.Yellow needles, m.p. 111 "C (from hexane-ethyl acetate) (Found: C, 65.7; H, 6.9; N, 3.6. C2,H,,N0,S requires C, 65.82; H, 6.78; N, 3.49%); [a]ifs -30.8 (c 2.8, CHCI,); v,,,(KBr)/m-' 2952, 1702 and 1549; 6, 0.9 (3 H, s, Me), 1.10 (3 H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 2.04 (1 H, br s, OH), 2.80 (1 H, d, J 11.2, 10'-Ha), 3.19 (1 H, d, J 11.2, 10'-Hb), 3.77 (3 H, s, OMe), 3.86 (1 H, m, 2'-H), 4.59 (2 H, s, NCH,), 6.12 (1 H, s, CH=), 6.82 (2 H, d, J 8.7, ArH) and 7.29 (2 H, d, J 8.7, ArH); m/z 401 (M'), 384,249 and 221.(-)-a-( {(1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]-heptan-1 -yl jmethy1thio)maleimide 3g. Prepared from the suc- cinimide 2g (671 mg, 2.4 mmol) and NCS (332 mg, 2.5 mmol) in carbon tetrachloride (20 cm3) in 95% yield. Pale yellow prisms, m.p. 182-1 84 "C (from hexane-ethyl acetate) (Found: C, 59.8; H, 6.9; N, 5.0. C,,H,,NO,S requires C, 59.77; H, 6.81; N, 4.98%); -27.1 (c 1.0, EtOH); v,,,(KBr)/cm-' 3450, 2950, 1710, 1550 and 1330; 6, (CDCI,-CD,OD) 0.95 (3 H, S, Me),1.12(3H,s,Me),1.1-1.9(7H,m,bornylH),2.88(1H,d, J11.5,10'-Ha),3.25(1H,d,J11.5,lO'-Hb),3.33(1H,br,OH), 3.84 (1 H, br, 2'-H) and 6.17 (1 H, s, CH=); m/z 282 (M+ + l), 257,154,135 and 109. (-)-N-But-3-ynyl-a-({(1S,2R,4R)-2-Hydroxy-7,7-dimethyl-bicycloC2.2. llheptan- 1-yZ)methylthio)maleimide 3f.-To a solution of compound 3g (210 mg, 0.74 mmol), triphenylphos- phine (226 mg, 0.88 mmol) and but-3-yn-1-01 (0.07 ml, 0.88 mmol) in THF (30 cm3) at 0 "C was added dropwise a solution of diethyl azodicarboxylate (DEAD) (0.074 cm3, 0.88 mmol) in THF (5 cm3).After this addition, the reaction mixture was kept at room temp. overnight. The solvent was removed under reduced pressure and the residue was purified by chromato- graphy on silica with hexane-ethyl acetate (4: 1) to give compound 3f (245 mg, 99%) as yellow prisms, m.p. 86-87 "C (from hexane-ethyl acetate) (Found: C, 64.8; H, 6.8; N, 4.1. C,,H,,NO,S requires C, 64.85; H, 6.95; N, 4.20%); Cali5 -33.0 (c 1.8, CHCl,); vma,(KBr)/crnp1 3550, 3290, 2960, 1760, 1700,1550, 1400 and 980; d"0.92 (3 H, s, Me), 1.1 1 (3 H, s, Me), 1.14-1.98 (7 H, m, bornyl H), 1.97 (1 H, t, J 2.7, 4"-H), 2.00 (1 H, br s, OH), 2.51 (2 H, dt, J 7 and 2.7, NCH,CH,), 2.84 J.CHEM. SOC. PERKIN TRANS. 1 1994 2.0 (7 H, m, bornyl H), 3.06 (1 H, d, J 13, 10'-Ha), 3.42 (1 H, br, OH), 3.48 (1 H, d, J 13, 10'-Hb), 4.05 (1 H, dd, J8 and 4,2'-H), 4.64(1H,d,J15,NCHH),4.71(1H,d,J15,NCHH),7.15(1H, s, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 388 (M' + l), 370,235, 135 and 93. (1)-N-(tert-Butyldimethylsily1)-a-({(1 S,2R,4R,Rs)-2- hydroxy-7,7-dimethylbicycl0[2.2.1Iheptan-1-yl }methysulJinyl)- maleimide Id. Prepared from sulfide 3d (1.83 g, 4.63 mmol) and MCPBA (882 mg, 5.1 mmol) in -100% yield. Needles, m.p. 107-109 "C (from light petroleum) (Found: C, 57.1; H, 7.9; N, 3.4.C,,H3,N04SiS-1/2H,0 requires C, 57.11; H, 8.15; N, 3.33%);[a]h5 +40.4 (c 2.1, CHC1,); vmax(KBr)/cm-' 3450,2960, 1710and1310;6,0.46(6H,s,SiMe3),0.88(3H,s,Me),0.95(9 H, s, SiBu'), 1.10 (3 H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 3.07 (1 H, d, J 12.7, 10'-Ha), 3.48 (1 H, br s, OH), 3.49 (1 H, d, J 12.7, (lH,d,Jll,SCHH),3.23(1H,d,Jll,SCHH),3.71(2H,t,J10'-Hb), 4.09 (1 H, m, 2'-H) and 7.14 (1 H, s, CH=). 7, NCH,), 3.90 (1 H, m, 2'-H) and 6.16 (1 H, s, CH=); m/z 333 (M+), 317,302,274 and 181. General Procedure for Preparation of N-Substituted a-({(1S,2R,4R, RS)-2-Hydroxy-7, 7-dimethylbicyclo C2.2.13 heptan- 1-yl )methysulJinyl)maleimides 1.-To a solution of this maleimide 3 (0.85 mmol) in methylene dichloride (30 cm3) at 0 "C was added dropwise a solution of MCPBA (1.2-1.4 mol equiv.) in methylene dichloride (20 cm3).After this addition, the mixture was allowed to reach room temp. and was stirred for a further 2-3 h. The mixture was then cooled to -70 "C to precipitate 3-chlorobenzoic acid, which was filtered off with suction. The filtrate ( -30 cm3) was diluted with diethyl ether (50 cm3). The organic phase was washed successively and quickly with cold, saturated aq. sodium hydrogen carbonate (20 cm3 x 2) and saturated brine (20 cm3), and was dried. The solvent was evaporated off under reduced pressure and the residue was suctioned by a vacuum pump to give the corresponding compound 1 as a semi-solid in nearly quantitative yield.All attempts at further purification by column chromato- graphy on silica resulted in decomposition of the product. ( -)-a-(((1S,2R,4R,R,)-2-Hydroxy-7,7-dimethylbicyclo-C2.2. llheptan- 1-yl )methysu&nyl)-N-methylmaleimidela. Pre-pared from sulfide 3a (800 mg, 2.71 mmol) and MCPBA (563 mg, 3.26 mmol) in -100% yield. Prisms, m.p. 152-155 "C (from hexane-ethyl acetate) (Found: C, 57.6; H, 6.6; N, 4.4. C15H,,N0,S requires C, 57.86; H, 6.80; N, 4.50%); Cali3 -12.0 (c 1.0, CHCl,); v,,,(KBr)/cm-' 3400, 1700, 1440 and 1380; 6, 0.88 (3 H, s, Me), 1.08 (3 H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 3.08 (1 H, d, J 13, 10'-Ha), 3.08 (3 H, s, NMe), 3.43 (1 H, br, OH), 3.49 (1 H, d, J 13, 10'-Hb), 4.07 (1 H, br, 2'-H) and 7.18 (1 H, s, CH=); m/z 311 (M'), 159,135 and 93.( +)-a-({(1S,2R,4R,R,)-2-Hydroxy-7,7-dimethylbicyclo-C2.2. llheptan-1 -yl )methysulJinyl)-N-phenylmaleimidelb. Pre-pared from sulfide 3b (1.SO g, 4.2 mmol) and MCPBA (727 mg, 4.2 mmol) in -100% yield. Pale yellow needles, m.p. 129- 131 "C (from pentanediethyl ether) (Found: C, 64.15; H, 6.2; N, 3.6. C,,H,,NO,S requires C, 64.33; H, 6.21; N, 3.75%); [a]? +89.2 (c 0.97, CHC1,); vma,(CHCl,)/cm-' 2950, 1720, 1505, 1390 and 1080; 6, 0.87 (3 H, s, Me), 1.10 (3 H, s, Me), 1.1-2.0 (7 H, m, bornyl H), 3.15 (1 H, d, J 13, 10'-Ha), 3.43 (1 H, br, OH), 3.59 (1 H, d, J 13, 10'-Hb), 4.11 (1 H, dd, J8 and 4, 2'-H) and 7.2-7.6 (6 H, m, CH= and ArH); m/z 373 (M'), 355, 221 and 135. ( +)-N-Benzyl-a-({(1S,2R,4R,Rs)-2-hydroxy-7,7-dirnethylbi-cycloC2.2.I] heptan-1-yl )methysu&nyl)rnaleimide lc.Prepared from sulfide 3c (4.05 g, 10.9 mmol) and MCPBA (2.65 g, 15.4 mmol) in -100% yield. An amorphouspowder (Found: C, 65.1; H, 6.5; N, 3.5. C21H25N04S requires C, 65.10; H, 6.50; N, 3.62%); [a]h6 +45.8 (c 1.0, CHC1,); v,,,(CHCl3)/cmp' 1710, 1390, 1070 and 750; 6, 0.87 (3 H, s, Me), 1.07 (3 H, s, Me), 0.8-( +)-a-({(1S,2R,4R,Rs)-2-Hydroxy-7,7-dimethylbicyclo-C2.2.1 Iheptan- 1-yl )methysulJinyl)-N-(4-methoxybenzyl)male-imide le. Prepared from sulfide 3e (340 mg, 0.85 mmol) and MCPBA (206 mg, 1.19 mmol) in -100% yield. A foam (Found: M+, 417.1658. C2,H,,N05S requires M, 417.1610); [a]fp +49.0 (c 1.1, CHCl,); v,,,(neat)/cm-' 3466, 2953, 1708, 15 15 and 1245; 6,0.88 (3 H, S, Me), 1.08 (3 H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 3.07 (1 H, d, J 13, 10'-Ha), 3.40 (1 H, br s, OH), 3.49 (1 H, d, J 13, 10'-Hb),3.79 (3 H, s, OMe), 4.09 (1 H, m, 2'- H),4.61(1H,AofABq,J14.4,NCHH),4.67(1H,BofABq,J 14.4, NCHH), 6.84-7.32 (4 H, m, ArH) and 7.14 (1 H, s, CH=); m/z 417 (M'), 265,135,121 and 93.(-)-N-But-3-ynyl-a-({( 1S,2R,4R,RS)-2-hydroxy-7,7-dimeth-ylbicycloC2.2. llheptan- 1-yl )methysulJinyZ)maleimide If. Pre-pared from sulfide 3f (5.0 g, 15 mmol) and MCPBA (2.70 g, 15.6 mmol) in 94% yield. Prisms, m.p. 130-1 3 1 "C (from diethyl ether) (Found: C, 61.7; H, 6.7; N, 3.9. C,,H,,NO,S requires C, 61.88; H, 6.64; N, 4.01%); [a]? -59.0 (c 1.05, CHCl,); v,,,(KBr)/crn-' 3400, 2950, 1720, 1700, 1400 and 1040; 6,0.85 (3 H, s, Me), 1.13 (3 H, s, Me), 1.25-1.89 (7 H, m, bornyl H), 1.95 (1 H, t, J 2.7, 4-H), 2.57 (2 H, dt, J 6.7 and 2.7, NCH,CH,), 3.05 (1 H, d, J 14, 10'-Ha), 3.31 (1 H, br d, J 3.7, OH), 3.76 (2 H, t, J6.7, NCH,), 3.80 (1 H, d, J 14, 10'-Hb), 4.1 1 (I H.m, 2'-H) and 7.18 (1 H, s, CH=); m/z 349 (M'), 331, 316, 283 and 197. General Procedure of Diels-Alder Reaction of Maleimides 1 and Cyc1opentadiene.-(a) In thepresence of a Lewis acid. To a solution of a sulfoxide 1 (0.3 mmol) in dry methylene dichloride (25 cm3) at the temperature indicated in Table 1 was added zinc chloride (1.5 mol equiv.) in one portion. After the mixture had been stirred at that temperature for 0.5 h, cyclopentadiene (5-20 mol equiv.) was added via a syringe. The mixture was stirred at that temperature for 0.5-1 h, then was poured onto cold, 1 mol dm-, hydrochloric acid (15 cm3), and the organic layer was separated. The aqueous phase was extracted with methylene dichloride (10 cm3 x 3) and the combined organic phase was washed with saturated brine and dried.The solvent was evaporated off under reduced pressure and the residue was purified by chromatography on silica with hexane%thyl acetate (5 :1+1 :1) to give the adducts 4 and 5. The major adducts 4 obtained from the reaction were isolated in 70-80% yield by recrystallisation of the reaction mixture. (b) Without a Lewis acid. To a solution of a sulfoxide 1 ( -0.3 mmol) in methylene dichloride (5 cm3) at 0°C was added dropwise cyclopentadiene (20 mol equiv.) via a syringe.After being stirred for 0.5 h, the solvent and the excess of cyclopentadiene were evaporated off under reduced pressure. The residue was purified by chromatography on silica with hexane-ethyl acetate (6: 1--+ 1 :1) to give the adducts 4 and 5. The adducts 5a and 5e were separated from their diastereo- isomers 4a and 4e by PLC [hexane-ethyl acetate (6:1), 30 J. CHEM. SOC. PERKIN TRANS. I 1994 developments], respectively. All attempts to isolate compounds conditions as follows. A solution of compound 4g (50 mg, 0.14 5b and 5c by chromatography were unsuccessful. mmol), triphenylphosphine (47 mg, 0.18 mmol) and benzyl (1R,4S)-(-)-2-exo-(((1S,2R,4R,Rs)-2-Hydroxy-7,7-dimeth-alcohol (0.02 cm3, 0.18 mmol) in THF (10 cm3) was stirred at ylbicyclo[2.2.1 Iheptan- 1-yl}methylsulJinyl)-N-methylbicyclo-room temp. for 10 min, after which DEAD (0.03 cm', 0.18 4a.A solid, mmol) as a solution in THF (5 cm3) was added dropwise to the C2.2.11hept-5-ene-2-endo,3-endo-dicarboximide m.p. 137-139 "C (from aq. MeOH) (Found: C, 63.9; H, 7.4; N, mixture. After being stirred at that temperature for 24 h, the 3.6. C20H27N04Srequires C, 63.64; H, 7.21; N, 3.71%); mixture was evaporated under reduced pressure. The residue -1.3 (c 0.4, CHCl,); ~,~,(CHCl,)/crn-' 2950, 1700, 1030 and was purified by chromatography on silica with hexane+thyl 750; 6, 0.91 (3 H, s, Me), 1.16 (3 H, S, Me), 1.1-2.0 (8 H, m), acetate (4: 1) to afford compound 4c (50 mg, 80%), identical 2.31 (1 H, d, J9, 7-Ha), 2.89 (3 H, s, NMe), 3.13 (1 H, d, J9, 7- with that obtained earlier.Hb), 3.47 (1 H, d, J 13, 10'-Ha), 3.49 (1 H, br, CH), 3.57 (1 H, d, (1 R,4S)-( -)-2-exo-((( 1S,2R,4R,RS)-2-Hydroxy-7,7-dimeih-J 13, 10'-H'), 3.61 (1 H, br, CH), 3.82 (1 H, br, CH), 4.01 (1 H, ylbicycloC2.2. llheptan- 1-yl}methylsulJinyl)-N-(4-methoxy-br, 2'-H), 6.29 (1 H, dd, J 5.5 and 3, CH=) and 6.36 (1 H, dd, J benzyl)bicyclo[2.2.1 Jhep t -5-ene-2 -en do,3 -endo -dicarboximide 5.5 and 3, CH=); m/z 378 (M' + l), 360,301,225 and 159. 4e. Prisms, m.p. 126-127 "C (from hexane-ethyl acetate) (Found: C, 67.2; H, 6.7; N, 2.9. C2,H,,N0,S requires C, 67.05; (1 R,4S)-( -)-2-exo-( {( 1S,2R,4R,Rs)-2-Hydroxy-7,7-dimethyl~-bicycloC2.2.1 Iheptan- 1-yl }methylsu@nyl)-N-phenylbicyclo-H, 6.88; N, 2.90%); Calk3 -7.8 (c 2.0, CHCl,); vmax(KBr)/cm-' C2.2.1]hept-5-ene-2-endo,3-endo-dicarboximide4b.Prisms, 3400, 2956, 1772, 1705, 1512, 1246 and 1038; 6, 0.67 (3 H, S, m.p. 187-189 "C (from hexane-ethyl acetate) (Found: C, 68.3; Me), 0.94 (3 H, s, Me), 1.C1.1 (1 H, m, bornyl H), 1.25-1.4 (1 H, 6.6; N, 3.1. C25H29N04S requires C, 68.32; H, 6.65; N, H, m, bornyl H), 1.37 (1 H, d, J 9.3, 7-Ha), 1.5-1.8 (5 H, m, 3.19%); Cali3 -23.8 (c 1.O, CHCl,); v,,,(KBr)/cm-' 2960, bornyl H), 2.13 (1 H, d, J9.3, 7-H'), 2.70 (1 H, d, J 12.9, 10'- 1710, 1370 and 1190; 6, 0.88 (3 H, S, Me), 1.16 (3 H, s, Me), Ha),3.21(1H,d,J12.9,lO'-Hb),3.25(1H,d,J4.4,3-H),3.39(1 0.8-2.0 (8 H, m, bornyl H and 7-Ha), 2.37 (1 H, d, J 9, 7-Hb), H, br s, 1-or 4-H), 3.52 (1 H, d, J2.9, OH), 3.69 (3 H, s, OMe), 3.17 (1 H, d, J 13, 10'-Ha), 3.55 (1 H, d, J 13, 10'-Hb), 3.61 (1 H, 3.73 (1 H, br s, 4- or 1-H), 3.94.0 (1 H, m, 2'-H), 4.39 (2 H, d, J3,OH), 3.61 (1 H, br, l-or4-H), 3.69(1 H,d, J4,3-H),3.94 ABq, J 13.9, AV 16.6 Hz, NCH,), 6.02 (2 H, S, CH=), 6.73 (2 H, (1 H,br,4-orl-H),4.05(1H,dt,J8and4,2'-H),6.45(1H,dd,d, J 8.6, ArH) and 7,18 (2 H, d, J 8.6, ArH); 483 (M +), 33 1,265 J 5 and 3, CH=), 6.52 (1 H, dd, J 5 and 3, CH=) and 7.1-7.5 and 121.(5 H, m, ArH); m/z 440 (M' + l), 422,287 and 221. (1 R,4S)-( +)-2-exo-({( 1S,2R,4R,Rs)-2-Hydroxy-7,7-dimeth-(1 R,4S)-( -)-N-Benzyl-2-exo-(((1S,2R,4R,Rs)-2-hydroxy-ylbicycloC2.2.1 Iheptan- 1-yl}methylsulJinyl)-N- But-3-ynylbi- 4f. Prisms,7,7-dimethylbicyclo[2.2.llheptan-1-yl )methylsulJinyl)bicyclo-cyclo[2.2.1] hept-5-ene-2-endo,3-endo-dicarboximide I:2.2.13hept-5-ene-2-endo,3 -endo-dicarboximide 4c.Needles, m.p. 64-66 "C (from pentaneaiethyl ether) (Found: C, 66.5; H, m.p. 172-173 "C (from hexane-ethyl acetate) (Found: C, 68.9; 7.3; N, 3.2. C23H29N04S requires C, 66.49; H, 7.04; N, H, 7.0; N, 2.9. C,,H,,N04S requires C, 68.85; H, 6.89; N, 3.37%); [a]i5 +3.9 (c 2.0, CHCI,); + 17.2 (c 0.8, acetone); 3.09%); Cali6 -4.4 (c 1.O, CHC1,); v,,,(KBr)/cm-' 3400,2960, v,,,(KBr)/cm-l 3460,3260,2960,1700,1450,1400 and 1030; 6, (3 H, s, Me), 1.03 (3 H, s, Me), 1.O-0.90 (3 H, s, Me), 1.16 (3 H, s, Me), 1.2-1.9 (8 H, m, bornyl H 1700, 1170 and 1035; ~3~0.77 1.9 (8 H, m, bornyl H and 7-Ha), 2.23 (1 H, d, J 9, 7-Hb), 2.86 and 7-Ha), 1.95 (1 H, t, J2.7, 4-H), 2.30 (1 H, d, J9.3, 7-H'), (1 H, d, J 13, 10'-Ha), 3.33 (1 H, d, J 13, 10'-Hb), 3.39 (1 H, d, 2.42 (2 H, dt, J6.8 and 2.7, 2"-H), 3.10 (I H, d, J 13, 10'-Ha), J4.5,3-H), 3.47(1 H, br, 1-or4-H), 3.59(1 H,d, J3.5,OH),3.81 3.46(1 H,d, J13, 10'-Hb),3.52(2H, brs,6-and 1-or4-H),3.57 (1 H, br, 4- or 1-H), 3.99 (1 H, ddd, J8,4 and 3.5, 2'-H), 4.49 (2 H, t, J6.8, NCH,), 3.60 (1 H, d, J3.5, OH), 3.83 (1 H, br s, (1 H, d, J 14, NCHH), 4.56 (I H, d, J 14, NCHH), 6.09 (2 H, br, 4- or 1-H), 4.02 (I H, dt, J4.0, 3.5, 2'-H), 6.30 (1 H, dd, J5.5, CH=) and 7.2-7.4 (5 H, m, ArH); 6,19.8,20.4,27.1, 30.9, 38.4, 3.0, CH=) and 6.37 (1 H, dd, J 5.5 and 3.0, CH=); m/z 416 (M' 42.6, 45.0, 45.3, 45.5, 46.0, 48.4, 49.1, 49.9, 51.1, 71.3, 76.8, + I), 398,332,263 and 197.128.1, 128.6, 128.8, 135.2, 135.8, 138.3 and 174.2; m/z 454 The d.e.was estimated as 96% (98:2) by HPLC analysis (M' + I), 353,301 and 235. Chexane-ethyl acetate-methanol (1 0 :1 :O.l), flow rate I .5 cm3 (1 R,4S)-( +)-2-exo-({(1S,2R,4R,Rs)-2-Hydroxy-7,7-dimeth-min-'; t, 4f 19.8 min; 5f 21.9 min]. ylbicyclo C2.2.11 heptan- 1-yl }methylsu@nyl)bicyclo C2.2.13 hept- (1 S,4R)-( -)-2-exo-( ((1S,2R,4R,Rs)-2-Hydroxy-7,7-dimeth-4g. The adducts 4d and 5d ylbicyclo C2.2.1)heptan- 1-yl }methy lsu@nyl)-N-methy lbicy clo- 5-ene-2-endo,3-endo-dicarboximide were acid labile and cleavage of the SiMe,Bu' group took place C2.2.1Jhept-5-ene-2-endo,3-endo-dicarboximide5a. Needles, during purification by chromatography on silica. The major m.p. 186188 "C (from aq. methanol) (Found: C, 62.6; H, 7.0; requires C, 62.64, H, 7.20; N, adduct was thus isolated as compound 4g after protodesilyl- N, 3.6.C20H2,N04S~1/3H20 ation by exposure to silica on a column for 1 day followed by 3.61%); -29.1 (c 0.7, CHCl,); vrnax(KBr)/cm-' 3400, elution with hexane-ethyl acetate (1 :1). 1700, 1290 and 1000; 6, 0.87 (3 H, S, Me), 1.13 (3 H, s, Me), Compound 4g: prisms, m.p. 230-232 "C (from hexane-ethyl 1.C2.0 (8 H, m, bornyl H and 7-Ha), 2.07 (1 H, d, J9, 7-Hb), acetate) (Found: C, 62.7; H, 6.9; N, 3.9. C,9H25N04S requires 2.64 (1 €3, d, J 13, 10'-Ha), 2.90 (3 H, s, NMe), 3.26 (1 H, br, C, 62.79; H, 6.93; N, 3.85%); Calk6 +2.4 (c 2.1, CHCl,); Calk6 1-or4-H), 3.50(1 H,d, J3,3-H), 3.55(1 H, br,4-or 1-H), 3.71 + 11.7(c 1.7, acetone); v,,,(KBr)/cm-' 3500, 3210, 2950, 1770, (1 H, d, J 5, OH), 3.73 (1 H, d, J 13, 10'-Hb), 4.00 (1 H, ddd, J 1710, 1340 and 1200; 6, 0.89 (3 H, S, Me), 1.14 (3 H, s, Me), 8,5and4,2'-H),6.26(1H,d,J7.5,CH=)and6.29(1H,d,J7.5, 1.1-1.3 (1 H, m, bornyl H), 1.4-1.7 (2 H, m, bornyl H), 1.7-1.95 CH=); HRMS (Found: M+ + 1, 378.1703.C20H,7N04S (5 H, m, bornyl H and 7-Ha), 2.25 (1 H, br d, J9, 7-Hb), 3.01 requires M + 1, 378.1737); m/z 378 (M' + l), 360, 294, 225 (1 H, d, J 13, 10'-Ha), 3.47 (1 H, d, J 13, 10'-Hb), 3.49 (2 H, br and 159. s, 1-or 4-H and 3-H), 3.61 (1 H, br d, J3, OH), 3.82 (1 H, br s, The adducts 5b and 5c could not be isolated in pure form; 'H 4- or 1-H), 4.02 (1 H, br t, J4,2'-H), 6.38 (1 H, dd, J5.4and 3.2, NMR spectral data of 5b:6,0.86 (3 H, s, Me), 1.12 (3 H, s, Me), CH=), 6.45 (1 H, br d, J5.4, CH=) and 8.36(1 H, br s, NH); m/z 1.1-2.0 (8 H, m, bornyl H and 7-Ha), 2.16 (1 H, d, J9, 7-Hb), 2.69 364 (M' + l), 346,280,263,211 and 135.(1 H, d, J 13, 10'-Ha), 3.43 (1 H, br, 1-or 4-H), 3.55 (1 H, d, J The diastereoisomeric excess (d.e.) was estimated as >99% 3,OH),3.62(1H,br,4-or1-H),3.72(1H,d,J13,10'-Hb),3.89 by HPLC analysis [hexane-ethyl acetate-methanol (5 :1 :OS), (1 H, d, J4, 3-H), 4.04(1 H, ddd, J8,4and 3, 2'-H), 6.44(2 H, flow rate 1.5 cm3 min-'1. The absolute stereochemistry of the br, CH=) and 7.1-7.5 (5 H, m, ArH). unstable compound 4d was confirmed by transformation of 'H NMR spectral data for adduct 5c: 6, 0.65 (3 H, s, Me), compound 4g into known compound 4c under Mitsunobu 1.OO (3 H, s, Me), 0.8-1.9 (8 H, m, bornvl H and 7-Ha).2.09 (1 H d, J9,7-Hb),2.40(1 H,d, J13, 10'-Ha), 3.33(1 H, br, 1-or4-H), 3.46(1 H,d, J3.5,3-H),3.50(2H,d + br, J13, 10'-Hband4-or I-H), 3.73 (1 H, d, J4, OH), 3.92 (1 H, m, 2'-H), 4.51 (1 H, d, J 14, NCHH), 4.57 (1 H, d, J 14, NCHH), 6.09 (2 H, br, CH=) and 7.2-7.4 (5 H, m, ArH). (1 S,4R)-( +)-2-exo-({( 1S,2R,4R,Rs)-2-Hydroxy-7,7-dimeth-ylbicyclo[2.2.1 Iheptan- 1 -yl}methylsulJinyl)-N-(4-methoxy-benzyl)bicyclo[2.2.l]hept-5-ene-2-endo,3-endo-dicarboximide 5e. Needles, m.p. 148-1 50 "C (from hexane-ethyl acetate) (Found: 67.0; H, 6.6; N, 2.9. C2,H,,N0,S requires C, 67.05; H, 6.88; N, 2.90%); Calk3 +61.1 (c 2.0, CHCl,); v,,,(KBr)/cm-' 3444,2952,1764,1696 and 1034; SH0.62 (3 H, s, Me), 0.98 (3 H, s, Me), 1.05-1.25 (1 H,m, bornyl-H), 1.4-1.5 (2H,m, bornylH), 1.6-1.85 (5 H, m, bornyl Hand 7-Ha), 2.10 (1 H, d, J9.3, 7-Hb), 2.32(1 H,d, J12.9, 10'-Ha), 3.35(1 H, br,s, 1-or4-H),3.41 (1 H, d, J 12.9, 10'-Hb), 3.45 (1 H, d, J3.4, OH), 3.49 (1 H, br s, 4- or l-H),3.71(1 H,d,J4.4,3-H),3.76(3H,s,OMe),3.97(1H,ddd, J 8.1, 4.2 and 3.4, 2'-H), 4.44 (1 H, A of ABq, J 13.9, NCHH), 4.51 (1 H, BofABq, J13.9,NCHH),6.09(2H, brs,CH=),6.80 (2 H, d, J 8.7, ArH) and 7.26 (2 H, d, J 8.7, ArH); m/z 483 (M'), 331,265 and 121.General Procedure of Diels-Alder Reaction of Maleimides lc and le with Furan.-(a) In thepresence of ZnC1,. To a solution of compound 1 (0.2 mmol) in dry methylene dichloride (5 cm3) at the temperature indicated in Table 4 was added ZnC1, (1.5 mol equiv.) and the mixture was stirred at that temperature for 0.5 h.To the solution was added dropwise furan (20 mol equiv.) via a syringe. After being stirred for 0.542 h, the mixture was poured onto cold, 1 mol dm-, HCl(l0 cm3). The organic phase was separated and the aqueous layer was extracted with methylene dichloride (5 cm3 x 3). The combined extracts were washed with saturated brine (20 cm3), dried, and concentrated. The residue was purified by chromatography on silica with hexane-ethyl acetate (2: 1) to give the adducts. (b) Without ZnC1,. A solution of compound lc (80 mg, 0.21 mmol) and furan (0.3 cm3, 20 mol equiv.) was stirred at 0 "C for 24 h. After the usual work-up, the crude product was purified by chromatography on silica with hexane-ethyl acetate (2 :1) to give adduct 6c (13 mg, 14%), adduct 8c (14 mg, 15%) and an inseparable mixture of diastereoisomers 7cand 9c (26 mg, 27%).(1 S,2S,6S,7R)-(-)-4-Benzyl-2-({(1 S,2R,4R,Rs)-2-hydroxy- 7,7-dimethylbicyclo[2.2.1]heptan-1-yl }methylsulJinyl)- 10-oxa-4-azatricyclo[5.2.1.02.6]dec-8-ene-3,5-dione6c.The reaction of compound lc (80 mg, 0.21 mmol) with furan (0.3 cm3, 4.13 mmol) at 0 "C for 0.5 h afforded the adducts 6c (48 mg, 51%) and 7c (1 4 mg, 15%). Compound 6c: needles, m.p. 143-144 "C (from hexane-ethyl acetate) (Found: C, 66.1; H, 6.4; N, 3.2. C25H29N05S requires C, 65.92; H, 6.42; N, 3.08%); Calk5 -26.9 (c 1.0, CHCl,); v,,,(KBr)/cm-' 2950, 1700, 1330, 1030 and 1020; S, 0.65 (3 H, s, Me), 0.96 (3 H, s, Me), 0.9-1.9 (7 H, m, bornyl H), 2.53 (1 H, d, J 13, 10'-Ha), 2.77 (1 H, s, 6-H), 3.25 (1 H, d, J 13, 10'-Hb), 3.39(1H,d,J3.5,OH),3.90(1H,dt,J8and3.5,2'-H),4.66(1 H, d, J 14, NCHH), 4.73 (1 H, d, J 14, NCHH), 5.37 (1 H, S, I-or7-H), 5.56(1 H,s, 7-or 1-H),6.69(1 H,dd, J6and2,CH=), 6.77 (1 H, dd, J 6 and 1.5, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 371,353,235,91 and 68.(I R,2S,6S,7S)-( -)-4-Benzyl-2-( {( 1S,2R,4R,Rs)-2-hydroxy-7,7-dimethylbicyclo[2.2.llheptan-1-yl}methylsulJinyl)- 10-oxa- 4-azatricyclo[5.2.1 .02*6]dec-8-ene-3,5-dione7c. Needles, m.p. 125-127 "C (from hexane-ethyl acetate) (Found: C, 65.5; H, 6.4; N, 3.1%); Calk5 -38.0 (c 1.0, CHCl,); v,,,(CHC1,)/cm~' 1710, 1650, 1390, 1340and 1070;6,0.71 (3H,s,Me), l.O0(3H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 2.37 (1 H, d, J 13, 10'-Ha), 3.19 (1 H, d, J13, 10'-Hb), 3.52(1 H, d, J3.4, OH), 3.61 (1 H, d, J 5.4, 6-H), 4.02 (1 H, ddd, J 8, 4 and 3.4, 2'-H), 4.54 (2 H, s, NCH,), 5.41 (1 H, S, 1-H), 5.44 (1 H, d, J5.4, 7-H), 6.27 (1 H, J.CHEM. SOC. PERKIN TRANS. 1 1994 dd, J 5.6 and 1.4, CH=), 6.30 (1 H, dd, J 5.6 and 1.7, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 371, 235, 135 and 91. The reaction of compound lc (100 mg, 0.26 mmol) and furan (0.94 cm3) conducted at 25 "C for 10 h afforded the adducts 6c and 8c (33 mg, 56%). The ratio 6c:& was 55:45 as judged by HPLC [hexane-ethyl acetate (2 :I), flow rate 1 cm3 min-'1. The adduct 8c was isolated by column chromatography on silica with hexane-ethyl acetate (1 : 1).(1 R,2R,6R,7S)-( -)-4-Benzyl-2-({(1 S,2R,4R,Rs)-2-hydroxy- 7,7-dimethylbicyclo[2.2.1]heptan-1-yl }methylsulJinyl)- 10-oxa-4-azatricyclo[5.2.1 .02*6]dec-8-ene-3,5-dione8c. Needles, m.p. 140-141 "C (from hexane-ethyl acetate) (Found: C, 65.8; H, 6.4; N, 3.3%); [a];' +27.4 (c 0.37, CHCl,); v,,,(CHCl,)/cm-' 1710, 1390, 1350 and 1030; 6, 0.74 (3 H, s, Me), 1.04 (3 H, s, Me), 1.0-1.9 (7 H, m, bornyl H), 2.33 (1 H, d,J 13, 10'-Ha), 3.25 (1 H,s,6-H), 3.32(1 H,d, J3.5,OH),3.88(1 H,d, J13, 10'-Hb), 3.91 (1 H,ddd,J8,4and3.5,2'-H),4.72(2H,s,NCH2),5.29(1 H, br s, 1-or 7-H), 5.40 (1 H, br d, J 1.5, 7- or 1-H), 6.43 (1 H, dd, J6 and 1.5, CH=), 6.71 (lH, dd, J6 and 1.5, CH=) and 7.2- 7.4 (5 H, m, ArH); m/z 235, 157,135 and 91. (I S,2R,6R,7R)-( - )-4-Benzyl-2-({(1 S,2R,4R,Rs)-2-hydroxy-7,7-dimethylbicyclo[2.2.llheptan-1-yl}methylsulJinyl)-10-oxa-4-azatricyclo[5.2.1 .02v6]dec-8-ene-3, 5-dione 9c.4, 0.80 (3 H, s, Me), 1.09 (3 H, s, Me), 1.1-1.9 (7 H, m, bornyl H), 2.62 (1 H, d, J 13, 10'-Ha), 3.43 (1 H, d, J3.5, OH), 3.82 (I H, d, J 13, 10'-Hb),3.98(1 H,d,J5.6,6-H),4.00(1 H,m,2'-H),4.54(2H,s, NCH,), 5.16(1 H,s, 1-H),5.46(1 H,d, J5.6,7-H),6.25(2H, br s, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 371, 235 and 91.Diels-Alder Reaction of the Maleimide lc and Cyclohexa- 1,3- diene.-(a) In thepresence of ZnCl,. To a solution of compound lc (98 mg, 0.25 mmol) in methylene dichloride (5 cm3) at -40 "C was added ZnC1, (52 mg, 0.38 mmol) in one portion. After the mixture had been stirred at that temperature for 0.5 h, cyclohexa-l,3-diene (0.48 cm', 20 mol equiv.) was added dropwise.After being stirred for 1 h and worked up as usual, the crude product was analysed by HPLC, which showed only a single diastereoisomer. The crude product was purified by chromatography on silica with hexane-ethyl acetate (2 :1) to give compound 10 (85 mg, 72%). (b) Without ZnCl,. To a solution of compound lc (50 mg, 0.13 mmol) in methylene dichloride (5 cm3) was added cyclohexa-1,3-diene (0.25 cm3, 20 mol equiv.) and the mixture was stirred for 10 h before being passed through a short pad of silica (2 g) with ethyl acetate to remove the polymerised material. Elution afforded adducts 10 and 11 (42 mg, 70%) in the ratio 22:78. The adduct 11 was separated from its diastereoisomer 10 by chromatography on silica with hexane- ethyl acetate (4 :1).(3aR,4R,7S,7aS)-( +)-2-Benzyl-3a-({(1 S,2R,4R,Rs)-2-hydr- oxy-7,7-dimethylbicyclo[2.2.llheptan-1-yl}methylsulJinyl)-3a ,4, -7,7a-tetrahydro-4,7-ethanoisoindole-1,3 -dione 10.Needles, m.p. 202-204 "C(from hexane-ethyl acetate) (Found: C, 69.3; H, 7.0; N, 2.8. C,,H,,NO,S requires C, 69.36; H, 7.11; N, 3.00%); Calk5 +28.2 (c 1 .O, KBr); v,,,(KBr)/cm-' 2590, 1700, 1350 and 1030; 6, 0.58 (3 H, s, Me), 0.88 (3 H, S, Me), 1.1-2.0 (10 H, m), 2.26 (1 H, m), 2.29 (1 H, d, J 13, 10'-Ha), 2.62 (1 H, d, J3, 7a-H), 3.11 (1 H, d, J 13, 10'-Hb), 3.26 (1 H, br, 4- or 7-H), 3.53(1 H,d, J3,OH), 3.60(1 H, br,7-or4-H), 3.97(1 H, ddd, J 8, 4 and 3, 2'-H), 4.58 (2 H, s, NCH,), 6.20 (1 H, t, J 7, CH=),6.30(1 H,t,J7,CH=)and7.2-7.4(5H,m,ArH);JC19.7, 20.2,22.8,27.0,31.0,32.5,38.5,42.6,45.0,46.6,48.2,48.5,51.1, 66.1,76.8, 128.3, 128.9, 133.4, 133.7,135.3, 173.1 and 175.3;mlz 468 (M' + l), 450,315 and 91.(3aS,4S,7R,7aR)-( -)-2-Benzyl-3a-({(1 S,2R,4R,Rs)-2-hy- droxy-7,7-dimethylbicyclo[2.2.llheptan-1-yl}methylsulJinyl)-3a,4,7,7a-tetrahydro-4,7-ethanoisoindole-1,3-dione 11. Prisms, m.p. 186-187 "C (from hexane-ethyl acetate) (Found: C,69.3; J3.4,9a-H),3.83(1 H,d,J13,lO'-Hb),3.85(1H,m,2'-H),4.312978, 1678, 1429, 1244 and 1082; SH1.20 (3 H, t, J7.1, Me), 1.38 J. CHEM. SOC. PERKIN TRANS. I 1994 H, 7.1; N, 2.9. C27H33N04S requires C, 69.36; H, 7.11; N, 3.00%); [a]h5 -5.5 (c 1.O, CHCl,); v,,,(KBr)/cm-' 1702, 1342, 1030 and 695;6,0.73 (3 H, s, Me), 1.01 (3 H, s, Me), 1.1-1.9 (1 1 H, m), 2.43 (1 H, d, J 13, 10'-Ha), 3.22 (1 H, m, 7-H), 3.31 (2 H, br, 4- and 7a-H), 3.45 (1 H, d, J 3, OH), 3.57 (1 H, d, J 13, 10'-Hb), 3.96 (1 H, ddd, J 8, 4 and 3, 2'-H), 4.61 (2 H, s, NCH,), 6.18(2H,m,CH=)and7.2-7.4(5H,m,ArH);m/z468(M++ I), 450, 315, 105 and 91.Diels-Alder Reaction of the Maleimide lc with Anthracene.-(a) In the presence of ZnC1,. To a solution of compound lc (60 mg, 0.16 mmol) in methylene dichloride (5 cm3) at 0 "C was added ZnC1, (32 mg, 0.23 mmol) in one portion and the mixture was stirred for 0.5 h. To the mixture at -20 "C was added a solution of anthracene (55 mg, 0.31 mmol) in methylene dichloride (2 cm3). After being stirred at that temperature for 18 h followed by the usual work-up, the crude product was analysed by 'H NMR spectrum, showing only a single diastereoisomer. The crude product was then purified by chromatography on silica with hexane-thy1 acetate (6 : 1+4 : 1) to afford compound 12 (84 mg, 96%).(3aR,9aS)-( + )-2-Benzyl-3a-({ (1S,2R,4R,Rs)-2-hydroxy-7,7-dimethylbicyclo[2.2.1 Iheptan- 1-yl }methylsulfinyl)-3a,4,9,9a-tetrahydro-4,9-o-benzenobenz[f lisoindole- 1,3-dione 12. Prisms, m.p. 215-216 "C (from hexane-ethyl acetate) (Found: C, 74.2; H, 6.2; N, 2.3. C,5H3,N0,S requires C, 74.31; H, 6.24; N, 2.48%); [a]h5 + 3 1.6 (c 1.O, CHCl,); v,,,(KBr)/cm-' 3400,2940, 1700 and 1390; 6, 0.47 (3 H, s, Me), 0.83 (3 H, s, Me), 0.9-1.9 (7 H, m, bornyl H), 1.79 (1 H, d, J 12.5, 10'-Ha), 2.84 (1 H, d, J 3.5,9a-H), 2.96(1 H, d, J 12.5, 10'-Hb), 3.41 (1 H, d, J3.5, OH), 3.86(1 H,ddd, J8,4and3S72'-H),4.21 (1 H,d, J15,NCHH), 4.27(1 H,d, J15, NCHH),4.84(1 H,d, J3.5,9-H), 5.20(1 H,s, 4-H) and 6.9-7.6 (13 H, m, ArH); m/z 556 (M+ + l), 230, 202, 178 and 91.(b) Without a Lewis acid. To a solution of compound lc (70 mg, 0.18 mmol) in benzene (5 cm3) was added anthracene (35 mg, 0.2 mmol) and the mixture was heated at reflux for 4 h. After removal of the solvent, the residue was purified by chromatography on silica with hexane-ethyl acetate (4: 1 +2: 1) to give an inseparable mixture of diastereoisomers 12 and 13 (79 mg, 77%) in the ratio 56:44 as judged by 'H NMR spectroscopy. (3aS,9aR)-( + )-2-Benzyl-3a-({ (1S,2R,4R,RS)-2-hydroxy-7,7-dimethylbicyclo[2.2.13hep tan- 1-y1 }me thy lsulfin y1)- 3 a,4,9,9a- tetrahydro-4,9-o-benzenobenz[flisoindole- 1,3-dione 13 had 6, 0.96 (3 H, s, Me), 1-1.85 (7 H, m, bornyl H), 1.14 (3 H, s, Me), 2.96(1 H, d, J 13, 10'-Ha), 3.39(1 H,d, J2.9, OH), 3.67(1 H, d, (3 H, s, Me), 1.12 (3 H, s, Me), 1.1-2.2 (7 H, m, bornyl H), 1.61 (1 H, d, J9, 10-Ha), 1.93 (1 H, d, J9, 10-Hb), 2.79 (1 H, d, J3.9, 6-H), 2.99 (1 H, d, J 13, 10'-Ha), 3.16 (1 H, br s, 1-or 7-H), 3.28 (1 H, d, J 13, 10'-Hb), 3.48 (1 H, d, J 8.8, OH), 3.56 (1 H, br s, 7-or 1-H), 3.77 (1 H, d, J3, OH), 4.00 (1 H, m, 2'-H), 4.06 (1 H, d,J14.5,NCHH),4.42(1H,d,J8.8,5-H),4.78(1H,d,J14.5, NCHH), 5.83 (1 H, d, J 5.5 and 3, CH=), 6.23 (1 H, dd, J 5.5 and 3, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 456 (M+ + l), 438,303,237 and 91.(1 R,2S,SS,6R,7S)-( + )-4-Benzyl-5-hydroxy-4-azatricyclo-C5.2.1 .02*6]dec-8-en-3-one 15.-To a deoxygenated solution of sulfoxide 14 (80 mg, 0.18 mmol) and dry tert-butyl alcohol (0.1 7 cm', 1.76 mmol) in dry THF (1 0 cm3) was added a solution of SmI, (14.1 cm3, 1.41 mmol, 0.1 mol dm-, in THF) followed by hexamethylphosphoric triamide (HMPA) (0.8 cm3, 4.4 mmol). The intense purple suspension was stirred for 1.5 h and quenched with cold, 1 mol dmP3 HC1 (10 cm3). The mixture was extracted with chloroform (10 cm3 x 3) and the combined extracts were washed successively with dil. aq. sodium thiosulfate (10 cm3)and saturated brine (10 cm3). The organic phase was dried, and concentrated under reduced pr&ure.-The residue was purified by chromatography on silica with hexane-ethyl acetate (2: 1+0: 1) to give a mixture of 10-mercaptoisoborneol and the bis-sulfide 16 l2 (26 mg) in the ratio 48:33, and compound 15 (27 mg, 60%) as needles, m.p.143-145 "C (from hexane-ethyl acetate) (Found: C, 75.2; H, 6.9; N, 5.4, C,6H,7NO, requires C, 75.27; H, 6.71; N, 5.49%); [a];, +8.9 (c 0.95, CHCl,); v,,,(KBr)/cm-' 1640, 1450, 1330, 1060 and 700; BH 1.36 (1 H, d, J 8.5, 10-Ha), 1.54 (1 H, d, J 8.5, 10-Hb), 2.64 (1 H, dd, J 8 and 4, 6-H), 3.07 (1 H, br, 1- or 7-H), 3.20 (1 H, d, J8.5, OH), 3.2-3.3 (I H, m, 2-H), 3.26 (1 H, br, 7- or 1-H), 3.97 (1 H, d, J 14.5, NCHH), 4.34 (I H, d, J8.5, 5-H), 4.80 (1 H, d, J 14.5, NCHH), 5.65 (1 H, dd, J5.5 and 3, CH=), 6.07 (1 H, dd, J 5.5 and 3, CH=) and 7.2-7.4 (5 H, m, ArH); m/z 255 (M+), 189, 106 and 91.(1 R,2S,5S,6R,7S)-( + )-4-Benzyl-5-ethoxy-4-azatricyclo-C5.2.1 .02.6]dec-8-en-3-one 17.-A mixture of the alcohol 15 (1.350 g, 5.3 mmol) and PPTS (10 mg) in dry EtOH (70 cm3) was stirred at room temperature for 12 h. To the mixture was added anhydrous sodium carbonate (1 00 mg) and the mixture was filtered. The filtrate was concentrated under reduced pressure, and recrystallisation of the residue from diethyl ether afforded compound 17 (1.313 g, 88%) as a solid, m.p. 68-70 "C (Found: C, 76.25; H, 7.4; N, 5.2. C,,H,,NO2 requires C, 76.29; H, 7.47; N, 5.16%); [a]h4 + 26.1 (c 2.0, CHCl,); v,,,(KBr)/cm-' (1 H, A of ABq, J 14.5, NCHH), 4.37 (1 H, B of ABq, J 14.5, NCHH), 4.69 (1 H, s, 4-H), 4.89 (1 H, d, J3.4,9-H) and 6.7-7.6 (1 3 H, m, ArH).( 1R,2R,5s,6S, 7s)-( + )-4-Benzyl- 5-hydroxy-2-( { ( 1S,2R,4R, Rs)-2-hydroxy-7,7-dimethylbicyclo[2.2.l]heptan-l-yl )methyl- sulJiny~-4-azatricyclo[5.2.1.02.6]dec-8-en-3-one14.--To a solu-tion of imide 4c (100 mg, 0.22 mmol) in EtOH (10 cm3) was added in portions NaBH, (9.2 mg, 0.24 mmol) and the mixture was heated at reflux for 2 h. To the cooled mixture was added dropwise water (10 cm3) and most of the solvent was evaporated off under reduced pressure. The aqueous layer was extracted with chloroform (10 cm3 x 3). The combined extracts were washed with saturated brine, dried, and con- cen trated.The residual solid was purified by chromatography on silica with hexane-ethyl acetate (1 :1) to give compound 14 (94 mg, 93%) as needles, m.p. 204-206°C (from aq. methanol) (Found: C, 68.4; H, 7.4; N, 3.0. C,,H3,N04S requires C, 68.55; H, 7.30; N, 3.08%); [a];, +9.9 (c 1.0, CHCI,); v,,,(KBr)/cm 3400, 1660, 1070 and 1030; SH 0.86 (1 H, d, J8.4, 10-Ha), 1.54 (1 H, dt, J8.4 and 1.6, 10-Hb), 2.65 (1 H, ddd, J8.5, 4.2 and 1, 6-H), 3.0 (1 H, br, 1-or 7-H), 3.22 (1 H, dd, J8.5 and 4.6, 2-H), 3.3 (1 H, br, 7- or 1-H), 3.4 (2 H, m, OCH,), 3.81 (1 H, dd, J 14.4 and 1, NCHH), 4.07 (1 H, s, 5-H), 4.88(1 H, d, J 14.4, NCHH), 5.66 (1 H, dd, J5.6 and 2.8, CH=), 6.11 (1 H,dd,J5.6and 2.9,CH=)and 7.15-7.35(5 H,m, ArH). Racemate ( k )-17 (m.p. 78 "C) was obtained from the Diels- Alder adduct 30 of N-benzylmaleimide with cyclopentadiene.(1 S,2S,5S76S,7R)-( + )-4-Benzyl-5-hydroxy-2-({ (1 S,2R,4R,Rs)- 2-hydroxy-7,7-dimethylbicyc10[2.2.1Iheptan-1-yl )methylsul- finyl)-l O-oxa-4-azatricyclo[5.2.1.02*6]dec-8-en-3-one 18.-To a solution of imide 6c (94 mg, 0.21 mmol) in EtOH (8 cm3)-THF (3 cm3) was added NaBH, (8.6 mg, 0.23 mmol) and the mixture was stirred for an additional 6.5 h. The reaction mixture was poured into ice-water (-10 g) and most of the solvent was evaporated off under reduced pressure. The aqueous phase was adjusted to pH -4 by addition of dil. HC1 using a pH test paper, and was extracted with chloroform (10 cm3 x 3). The combined extracts were washed with saturated brine, dried, and concentrated to give compound 18(89 mg, 94%) as a solid, m.p.150 "C (from chloroform-hexane) (Found: C, 65.5; H, 6.8; N, 3.0. C,,H,,NO,S requires C, 65.62; H, 6.83; N, 3.06%); [a]h6 + 23.2 (c 1.O, CHCl,); v,,,(KBr)/crn-' 3390, 2950, 1660, 1455, 1080and1010;6H0.83(3H,s,Me),1.12(3H,s,Me),1.1-1.9 (7 H, m, bornyl H), 2.19 (1 H, s, 6-H), 3.10 (1 H, d, J 12.9, 10'-Ha), 3.32 (1 H, d, J 12.9, 10'-Hb), 3.37 (1 H, d, J6.6, OH), 3.55 (1 H, d, J 3.4, OH), 3.95 (1 H, m, 2'-H), 4.40 (1 H, d, J 15.4, NCHH), 4.81 (1 H, d, J 15.4, NCHH), 5.00 (1 H, d, J6.6, 5-H), 5.03 (1 H, br s, 1- or 7-H), 5.45 (1 H, br s, 7- or 1-H), 6.58 (1 H,dd, J5.9and 1.7, CH=),6.68(1 H, dd, J5.9and 1.5,CH=) and 7.3-7.4 (5 H, m, ArH). (1S,2S,5R76S,7R)-(+ )-4-Benzyl-5-hydroxy-2-((( 1 S,2R,4R,RS)- 2-hydroxy-7,7-dimethylbicyclo[2.2.1Iheptan-1-yl )methylsul- $nyl)-1O-oxa-4-azatricyclo[5.2.1.02,6]dec-8-en-3-one 19.-In a similar manner to compound 18, the adduct 6c (250 mg, 0.55 mmol) was treated with NaBH, (125 mg, 3.3 mmol) in methanol (25 cm3).After the mixture had been stirred for 6.5 h, cold water (20 cm3) was added and the resultant mixture was stirred for 0.5 h. The precipitate was collected, and recrystallised from hexane4hloroform to give compound 19(232 mg, 92%) as prisms, m.p. 142-145 "C (Found: C, 65.3; H, 6.9; N, 2.87. C,,H,,NO,S requires C, 65.62; H, 6.83; N, 3.06%); [a]h6+ 108.1 (c 1.0,pyridine); v,,,(KBr)/cm-' 3385,3270,2950, 1655 and 1055; 6, (C2H5]pyridine) 0.74 (3 H, s, Me), 1.02 (1 H, br t, J 7.3, bornylH), 1.29(3H, s, Me), 1.4-1.8 (5 H,m, bornyl H), 1.9- 2.1 (1 H,m, bornylH), 2.80(1 H,d, J7,6-H), 3.18(1 H,d, J13, 10'-Ha), 3.87 (1 H, d, J 13, 10'-Hb), 4.24 (1 H, dd, J 8 and 4, 2'-H), 4.47 (1 H, d, J 15, NCHH), 5.0 (2 H, br, OH), 5.22 (1 H, d, J 15, NCHH), 5.73 (1 H, d, J 7, 5-H), 5.9 (2 H, m, 1- and 7-H),6.65(1 H,dd,J5.5and2,8-H),6.95(1H,dd,J5.5and1.5, 9-H) and 7.3-7.6 (5 H, m, ArH).Isomerisation of the Alcohol 19 into compound 18.-(a) To a mixture of compound 19 (3 mg) in EtOH (10 cm3) was added sodium (800 mg, 0.04 mol) and the mixture was stirred at room temperature for 2 days. To the mixture was added ice- water (10 cm3) and the aqueous phase was extracted with chloroform (10 cm3 x 3). The combined extracts were washed with saturated brine, dried, and concentrated to give compound 18(1.3 mg, 43%).(b)To a solution of compound 19 (5 mg, 0.01 mmol) in THF (1 5 cm3) was added conc. HCl (1 drop) at room temperature. The mixture was stirred for 4 days and similar work-up to that in the method (a) afforded compound 18(3 mg, 60%). (1 S,2R,5S,6S,7R)-( + )-4-Benzyl-5-hydroxy- 10-oxa-4-azatri- cyclo[5.2.1 .02.6]dec-8-en-3-one 20.-Tn a similar manner to the reduction of compound 14 (-315), a solution of sulfoxide 18 (60 mg, 0.13 mmol) and tert-butyl alcohol (0.12 cm3, 1.3 mmol) in THF (30 cm3) was treated with a solution of SmT, (7.9 cm3, 0.79 mmol, 0.1 mol dm-, in THF) and HMPA (0.3 cm3) afforded compound20 (33 mg, 98%) as needles, m.p. 153-155 "C (from hexane-ethyl acetate) (Found: C, 70.25; H, 5.85; N, 5.3.C1,H,,NO3 requires C, 70.02; H, 5.88; N, 5.44%); [a]k4 + 79.8 (c 1.0, CHCI,); v,,,(KBr)/cm-l 3180, 1655, 1470, 1450and1080; dH 2.25 (1 H, dd, J 7 and 1, 2- or 6-H), 2.79 (1 H, d, J 7, 6- or 2-H), 3.13 (1 H, d, J8, OH), 4.20 (1 H, d, J 15, NCHH), 4.86 (1 H, d, J 15, NCHH), 4.86 (1 H, d, J8, 5-H), 4.92 (1 H, br d, J2, 1- or 7-H), 5.21 (1 H, br d, J2, 7- or 1-H), 6.38 (1 H, dd, J 6 and 2, CH=N), 6.45 (1 H, dd, J 6 and 2, CH=) and 7.2-7.4 (5 H, m, ArH). ( 1S,2R, 5R, 6S,7R)-( + )-4-Benzyl- 5- hydroxy- 10-oxa-4-azatri-cycloC5.2.1 .02,6]dec-8-en-3-one 21.411 a similar manner to the preparation of compound 20, a solution of compound 19 (45 J. CHEM. SOC. PERKIN TRANS. 1 1994 mg, 0.1 mmol) in THF (40 cm3) was treated with SmI, (7.9 cm3, 0.79 mmol) and HMPA (0.2 cm3) to give compound 21 (20 mg, 79%) as a solid, m.p.135-137 "C (from hexane-ethyl acetate) (Found: 70.0; H, 5.85; N, 5.5%); Calk5 + 169.8 (c 1.0, CHCI,); vma,(KBr)/cm-'314O, 1635,1455and 1120;6,2.58(1 H,dd, J7.4 and7,6-H),2.67(1 H,d, J7.4,2-H),2.68(1 H,d, J12.9,OH),4.15 (1 H,d, J14.7,NCHH),4.86(1 H,d, J14.7,NCHH), 5.03(1 H, dd, J12.9and7,5-H),5.15(1 H, brd, J1.5, l-or7-H),5.25(1 H, brd, J1.5,7-or l-H),6.38(1 H,dd, J5.8and 1.7,CH=),6.55(1 H, dd, J 5.8 and 1.7, CH=) and 7.3-7.4 (5 H, m, ArH). (1R*,2S*,5S*,6R*,7S*)-4-Benzyl-5-(p-tolylsulfonyl)-4-azat~i-cycl0[5.2.1 .02*6]dec-8-en-3-one 22.-To a solution of toluene-p-sulfinic acid (1.02 g, 6.55 mmol) in methylene dichloride (20 cm3) was added powdered CaCl, (727 mg, 6.55 mmol).After the mixture had been stirred for 5 min, a solution of racemate (&)-17 (370 mg, 1.31 mmol) in methylene dichloride (5 cm3) was added and the mixture was stirred for 0.5 h before being washed successively with water (10 cm3), saturated aq. sodium hydrogen carbonate (1 0 cm3) and saturated brine (1 0 cm3), dried and concentrated. The residue was purified by chromatography on silica with hexane-ethyl acetate (3: 1) to give compound ( k )-22 (368 mg, 71%) as a solid, m.p. 151- 152 "C (from hexane-ethyl acetate) (Found: C, 70.2; H, 5.8; N, 3.6. C2,H,,N0,S requires C, 70.21; H, 5.89; N, 3.56%); v,,,(neat)/cm-' 3060, 2980, 1740, 1700, 1400, 1300, 1290 and 1130; BH 1.19 (1 H, d, J 8.8, 10-Ha), 1.42 (1 H, d, J 8.8, 10-Hb), 2.33 (1 H, dd, J 8 and 4,2-H), 2.47 (3 H, s, Me), 2.84 (I H, ddd, J 8,4 and 1.5,6-H), 2.98 (1 H, br s, 1-or 7-H), 3.12 (1 H, br s, 7-or 1-H), 3.99 (1 H, br d, J 1.5,5-H), 4.32 (1 H, d, J 14, NCHH), 5.12(1H,d,J14,NCHH),5.23(1H,dd,J5and3,CH=),5.91 (1 H, dd, J 5 and 3, CH=), 7.32 (5 H, m, ArH), 7.40 (2 H, d, J 8, ArH) and 7.74 (2 H, d, J 8, ArH); m/z 394 (M' + l), 352, 344,336,254,238 and 174.Optically active sulfone ( + )-22 was obtained similarly from the ether (+)-17, as prisms, m.p. 161-163 "C (from hexane- ethyl acetate); Calk6 +29.4 (c 1.97, CHCl,); -100% e.e. determined by chiral HPLC analysis [Chiralcel OC; hexane- EtOH (5: l), flow rate 0.5 cm3 min-', t, (+)-22,55 min; (-)-22, 64 min].General Procedure for Preparation of (1 R*,2S*,5S*,6R*, 7S*)-4-Benzyl-4-azatricyc10[5.2.1.02.6]dec-8-en-3-ones 23.-The reaction was conducted on a 0.354.5 mmol scale. (a) Using an organocopper reagent. To a suspension of an organocuprate (2-3 mol equiv., prepared from 1.56 mol dmP3 organolithium or -0.5 mol dm-, Grignard reagent and CuBr-Me,S complex) in diethyl ether (10 cm3)was added a Lewis acid under argon at the temperature indicated in Table 3. After the mixture had been stirred at that temperature for 15 min, a solution of the ether (&)-17 (0.35-0.5 mmol) in diethyl ether (5 cm3) was added via a syringe. The reaction mixture was allowed to reach the temperature in Table 3 and was quenched with saturated aq. NH,Cl (20 cm3).The aqueous layer was extracted with methylene dichloride (20 cm3 x 3) and the combined extracts were washed with saturated brine, dried, and concentrated. The residue was purified by chromatography on silica with hexane-ethyl acetate (2: 1 for R2 = vinyl; 3 : 1 for R2 = butyl; 1 : 1 for R2 = allyl; 8 : 1 for R2 = heptyl) to afford compound ( k )-23 or a product mixture. (b) Using allyltrimethylsilane. To a solution of the ether ( k )-17 (0.35-0.5 mmol) in dry methylene dichloride (20 cm3) at the temperature indicated in Table 7 was added allyltrimethylsilane (4 mol equiv., 1.4-2 mmol) followed by a Lewis acid (2.5 mol equiv., 0.9-1.25 mmol; 1 rnol dm-, SnCl, in CH2Cl, or 1 mol dm-, TiCl, in CH2C12 or BF,.Et,O complex). After being stirred for the appropriate time, the mixture was quenched with cold water (20 cm3) followed by 2 rnol dm-, hydrochloric acid J. CHEM.SOC. PERKIN TRANS. 1 1994 (10 cm3). The aqueous layer was extracted with methylene dichloride (10 cm3 x 4) and the extracts were washed with saturated brine (10 cm3), dried, and concentrated. The product ( f)-23 (R2 = allyl) was isolated after column chromatography on silica. (c) From a sulfonyl lactam. To a stirred suspension of zinc bromide (263 mg, 1.17 mmol) in dry THF (10 cm3) was added a 0.35 mol dm-3 solution of heptylmagnesium bromide in THF (6.7 cm3, 2.34 mmol) oia a syringe. After the mixture had been stirred for 0.5 h, a solution of compound 22 (230 mg, 0.59 mmol) in dry THF (10 cm3) was added at 0 OC.The mixture was allowed to reach room temperature and was stirred for 14 h. The reaction mixture was cooled to 0°C and quenched with 1 mol dmP3 hydrochloric acid (10 cm3). The aqueous layer was extracted with diethyl ether (20 cm3 x 4) and the extracts were washed with saturated brine (30 cm3), dried, and concentrated. The residue was purified by flash chromato- graphy on silica to give compound 23 (R2 = heptyl) (164 mg, 83%).Compound ( k)-23 (R2 = vinyl) was an oil (Found: M+ 265.1485. C,,H19N0 requires M, 265.1465); v,,,(neat)/cm-' 2971, 1681, 1422and 1245;6, 1.32(1 H,d, J8.4, 10-Ha), 1.52(1 H, dt, J 8.4 and 1.7, 10-Hb), 2.48 (1 H, ddd, J9.3, 4 and 2.9, 6- H), 2.99 (1 H, br s, 1- or 7-H), 3.15-3.25 (2 H, m, 5- and 6-H), 3.30(1 H, brs, 7-or 1-H), 3.57(1 H,dd, J14.4and l,NCHH), 4.98 (1 H, d, J 14.4, NCHH), 5.06 (1 H, d, J 17, CH=), 5.19 (1 H, brd, JlO,CH=), 5.63(1 H,ddd, J17, lOand8.8,CH=), 5.69 (1 H,dd,J5.6and2.7,CH=),6.19(1H,dd, J5.6and2.9,CH=) and 7.05-7.35 (5 H, m, ArH); m/z 265 (M+), 199, 118 and 91.Compound (2)-23 (R2 = Bu) was an oil (Found: M+, 295.1892. C2,H2,N0 requires M, 295.1934); v,,,(neat)/crn-' 2930 and 1654; 6,0.89 (3 H, br t, J 7, Me), 1.05-1.67 (6 H, br, 3 x CH,), 1.34(1 H,d, J8.4, 10-Ha), 1.52(1 H,dt,J8.4and 1.7, 10-Hb),2.42(1H,ddd,J9.2,3.9and2.9,6-H),2.72(1H,ddd,J 6.9, 2.9 and 2.5, 5-H), 2.90 (1 H, br s, 7-H), 3.13 (1 H, dd, J9.2 and 4.4, 2-H), 3.29 (1 H, br s, I-H), 3.65 (1 H, dd, J 14.7 and 1, NCHH),4.98(1 H,d, J14.7,NCHH), 5.70(1 H,dd, J5.6and 2.9,CH=),6.19(1 H,dd, J5.6and3.0,CH=)and7.15-7.35(5H, m, ArH); m/z 295 (M+),229, 186, 172 and 91.Compound ( k )-23 (R2 = allyl) was obtained as plates, m.p. 81-82 "C(from hexane*thyl acetate) (Found: C,8 1.7; H, 7.3; N, 4.75. C,,H,,NO requires C, 81.68; H, 7.58; N, 5.01%); v,,,(KBr)/cm-' 2986, 2939, 1664, 1426, 1246 and 707; 6, 1.34 (1 H, d, J8.5,10-Ha), 1.52 (1 H, dd, J8.5 and 1.4, 10-Hb), 2.18 (1 H, m, 1'-Ha), 2.33 (1 H, m, 1'-Hb), 2.48 (1 H, ddd, J8.8, 3.3 and 2.9, 6-H), 2.84 (1 H, m, 5 H), 2.9 (1 H, br, 7-H), 3.12 (1 H, dd, J8.8 and 4.4,2-H), 3.3 (1 H, br s, 1-H), 3.69 (1 H, d, J 14.9, NCHH), 5.00 (1 H, d, J 14.9, NCHH), 5.1-5.2 (2 H, m, CH2=) 5.6-5.7 (1 H, m, CH=), 5.72 (1 H, dd, J 5.6 and 2.9, 8-H), 6.20 (1 H, dd, J 5.6 and 2.1,9-H) and 7.2-7.35 (5 H, m, ArH); m/z 279 (M +), 238, 172 and 91.Compound (+)-23 (R2 = heptyl) was an oil (Found: M+, 337.2385. C23H3 ,NO requires M, 337.2404); v,,,(neat)/cm-' 37 150 -220 "C; quartz tube: length, 48 cm; diameter, 16 mm; oven temp. 450 "C at 0.5 Pa, for 4 h) to give compound 25 (1 16 mg, 78%) as an oil (Found: M+, 271.1914. C,,H,,NO requires M, 271.1934); [a];' +42.4 (c 2.0, CHCl,); v,,,(neat)/cm-' 2926, 2855,1684and 1406;6,0.87(3H, brt, J6.5,Me), 1.1-1.4(10H, br,5 x CH,), 1.4-1.6(1 H,m), 1.7-1.85(1 H,m),3.95-4.0(1 H, m, 5-H),4.07(1 H,d, J15,NCHH), 5.12(1 H,d,J15,NCHH), 6.21(1H,dd,J5.9and1.5,3-H),7.02(1H,dd,J5.9and1.5,4-H) and 7.2-7.4 (5 H, m, ArH); m/z 271 (M+), 186, 173 and 91. E.e. 74% by chiral HPLC [Chiralpak AS; hexane-propan-2- 01 (19: l), flow rate 1 cm3 min-'; tR (-)-25, 39.2 min; (+)-25, 44.4 min].Racemate (k)-25 was prepared from racemate ( k )-22 (R2 = heptyl) by FVP. (5s)-(-)-1-Benzyl-5-heptylpyrrolidine-2-one24.-A solution of compound (+)-25 (25 mg) {Calk8 +42.4 (c 2.0, CHCl,)) and containing 5% Pt on alumina (200 mg) in tert-butyl alcohol (5 cm3) was hydrogenated at 3.5 atm for 5 h. The mixture was filtered and the filtrate was concentrated to give the saturated lactam (+)-24 l9 (24 mg, 95%) as an oil, Calk6 -13.3 (c 1.2, CH,Cl,) {lit.,19 [a];' -21.9 (c 1.2, CH,Cl,) for 294% e.e.}. (1 S,2S,5S,6S,7R)-( +)-4-Benzyl-5-ethoxy-2-({(1 S,2R,4R,RS)-2-hydroxy-7,7-dimethylbicyclo[2.2.1Jheptan-1-yl }methylsul- finy1)-1O-oxa-4-azatricycl0[5.2.1.02@Jdec-8-en-3-one26.-A mixture of imide 6c (1.43 g, 3.14 mmol) and NaBH, (360 mg, 9.24 mmol) in THF (30 cm3)-EtOH (100 cm3) was heated at 50 "Cfor 3 h.After the mixture had cooled to 0 OC, water (0.2 cm3), followed by conc. HCl (0.2 cm3), was added to the mixture. The mixture was heated at 50 "C for 2 days. Most of the solvent was evaporated off and the residue was partitioned between water (10 cm3) and chloroform (30 cm3). The aqueous layer was extracted with chloroform (20 cm3 x 4). The combined organic phases were washed with saturated brine (20 cm3), dried, and concentrated to give compound 26 (1.40 g, 92%) as prisms, m.p. 145-147 "C (from hexane*thyl acetate) (Found: C, 66.9; H, 7.1; N, 3.2. C,,H,,NO,S requires C, 66.78; H, 7.27; N, 2.88%); Calk6 +27.1 (c0.47, CHCl,); v,,,(KBr)/cm-' 2956, 1697, 1422 and 1074; 6, 0.83 (3 H, s, Me), 1.12 (3 H, s, Me), 1.1-1.2 (1 H, m, bornyl H), 1.15 (3 H, t, J 7.0, Me), 1.41.6(2H,m,bornylH), 1.7-1.9(4H,m, bornylH),2.14(1 H, S, 6-H), 3.22 (1 H, d, J 13, 10'-Ha), 3.35 (1 H, d, J 13, 10'-Hb), 3.45 (2 H, dq, J 6.9 and 4.9, OCH,), 3.63 (1 H, br, OH), 3.96-3.98 (1 H, m, 2'-H), 4.22 (1 H, d, J 15, NCHH), 4.62 (1 H, s, 5-H),4.94(1H,d,J15,NCHH),4.97(1H,brs,7-H),5.49(1H, brs,l-H),6.58(1H,dd,J5.8and1.6,CH=),6.73(1H,dd,J5.8 and 1.2, CH=) and 7.247.36 (5 H, m, ArH).(1 S,2R,5S,6S,7R)-( +)-4-Benzyl-5-ethoxy-lO-oxa-4-azatricy-cloC5.2.1 .02.6]dec-8-en-3-one 27.-To a deoxygenated solution of the sulfoxide 26 (1 SO g, 3.1 mmol), tert-butyl alcohol (3 cm', 31 mmol) and HMPA (5.6 cm3, 31 mmol) in THF (100 cm3) 5.6 and 2.9, CH=), 6.19 (1 H, dd, J5.6 and 2.9, CH=) and 7.15- 7.35 (5 H, m, ArH); m/z 337 (M+),294,271,238,186 and 172.In a similar manner to racemate (&)-23, compound (+)-23 (R2 =heptyl) was obtained from sulfone (+)-22 as an oil; [a]i4 +24.7 (c 2.1 ,CHCl,). (5s)-(+)-1 -Benzyl-5-heptyl- 1,5-dihydropyrrol-2-one 25 by Flash Vacuum Pyrolysis.-The lactam (+)-23 (R2 = heptyl) (1 84 mg, 0.55 mmol) was subjected to pyrolysis (sublimation at was added a solution of SmI, (1 54cm3, 15.4 mmol, 0.1 mol dmP3 2927, 2856, 1681 and 1428; 6, 0.89 (3 H, br t, J 6.7, Me), 1.25 in THF) over a period of 5 min. After an additional 0.5 h, the (12H, br,6 x CH,), 1.34(1 H,d, J8.4, 10-Ha), 1.52(1 H,dt, J mixture was quenched with water (10 cm3).Most of the THF 8.4 and 1.7, 10-Hb), 2.42 (1 H, ddd, J9.3, 4 and 3, 6-H), 2.73 was evaporated off and 1 mol dm-3 HCl(20 cm3) was added to (1 H, dt, J8 and 3,5-H), 2.91 (1 H, br s, 1-or 7-H), 3.13 (1 H, dd, the mixture. The aqueous layer was extracted with chloroform J9.3 and 4.6, 2-H), 3.29 (1 H, br s, 7- or 1-H), 3.66 (1 H, dd, J (20 cm2 x 5). The combined extracts were washed successively 14.7and1,NCHH),4.97(1H,d,J14.7,NCHH),5.70(1H,dd,Jwith aq. 0.5% sodium thiosulfate (10 cm3) and saturated brine (10 cm3), dried, and concentrated. The residue was purified by chromatography on silica with hexane*thyl acetate (2 :1) to give compound 27 (810 mg, 92%) as an oil (Found: M+, 285.1351.C1,H,,NO, requires M, 285.1363); Calk6 +74.1 (c 2.3, CHCI,); v,,,(neat)/cm-' 2976, 2927, 1694, 1445 and 1080; 6,1.16 (3 H, t, J7, Me), 2.25 (1 H, d, J7.1,2- or 6-H), 2.77 (1 H, d, J7.1,6- or 2-H), 3.39 (2 H, dq, J 12.9 and 7.0, OCH,), 4.05 (1 H,d, J15.3,NCHH),4.60(1 H,s, 5-H),4.85(1 H,s, 1-or7-H), 4.94(1 H, d, 515.3, NCHH), 5.21 (1 H, s, 7-or 1-H), 6.37 (1 H, d,J5.7,CH=),6.43 (1 H,d,J5.7,CH=)and 7.22-7.30(5 H,m, ArH); m/z 285 (M'), 217, 186,91 and 77. (1 S,2R,5S,6S,7R)-( +)-4-Benzyl-5-(p-tolylsulfonyl)-1O-oxa-4-azatricyclo[5.2.1 .02*6]dec-8-en-3-one 28.-In a manner similar to compound (+)-22, the ethoxy lactam 27 (810 mg, 2.8 mmol) was treated with toluene-p-sulfinic acid (2.7 g, 17.1 mmol) and powdered CaCl, (1.9 g, 17.1 mmol) in methylene dichloride (80 cm3) at room temperature for 17 h to give compound 28 (870 mg, 78%) as plates, m.p.134-135 "C (from hexane-ethyl acetate) (Found: C, 66.8; H, 5.4; N, 3.8. C22H21N04S requires C, 66.82; H, 5.35; N, 3.54%); [ct]k4 +75.3 (c 2.5, CHCl,); v,,,(KBr)/cm-' 3029, 2988, 1702 and 1595; 6, 2.02 (1 H, d, J 7, 2- or 6-H), 2.47 (3 H, s, Me), 2.49 (1 H, d, J 7, 6- or 2-H), 4.32(1 H,d, J15,NCHH),4.38(1 H,s, 5-H),4.82(1 H,s, 1-H), 5.17 (1 H, S, 7-H), 5.27 (1 H, d, J 15, NCHH), 6.36 (1 H, dd, J 5.8 and 1.6, CH=), 6.40 (1 H, dd, J5.8 and 1.5, CH=), 7.2-7.35 (5 H, m, ArH), 7.39 (2 H, d, J 8, ArH) and 7.69 (2 H, d, J 8, ArH); M/z 240, 172, 148 and 91. -100% E.e. was confirmed by chiral HPLC [Chiralcel OC; hexane-ethyl acetate (5: I), flow rate 1 cm3 min-'; tR (+)-28,56 min; (-)-28, 78.4 rnin].Racemate (+)-28 (m.p. 145-147 "C) was prepared from racemic (_+ )-27. (1 S,2R,5S,6R,7R)-( +)-4-Benzyl-5-heptyl-1O-oxa-4-azatricy-cloC5.2.1 .02*6]dec-8-en-3-one 29.-In a similar manner to its analogue (+)-23, compound (+)-29 (441 mg, 100%) was obtained by treatment of sulfone (+)-28 (510 mg, 1.29 mmol) in methylene dichloride (20 cm3) with solutions of heptyl- magnesium bromide (13.8 cm3, 0.56 mol dm-3 in diethyl ether, 7.74 mmol) and ZnBr, (871 mg, 3.87 mmol) in diethyl ether (50 cm3). Compound 29 was an oil (Found: M', 339.2169. C,,H2,N0, requires M, 339.2197); [ct]h7 +66.4(c 2.0, CHCl,); v,,,(neat)/cm-' 2927,2856, 1682 and 1445;6,0.88 (3 H, t, J6.7, Me), 1.23(10H,br, 5 x CH,), 1.3-1.7(2H,m),2.06(1 H,dd, J 7.6 and 2.7, 6-H), 2.72 (1 H, d, J7.6, 2-H), 3.29 (1 H, m, 5-H), 3.91 (1 H,d, J15.4,NCHH),4.74(1 H, brs, 7-H), 5.03(1 H,d, J 15.4,NCHH), 5.30(1 H, brs, 1-H), 6.36(1 H,dd, J5.9and 1.5, 8-H),6.44(1H,dd,J5.9and1.5,9-H)and7.1-7.4(5H,m,ArH).-100% E.e. by chiral HPLC [Chiralcel OC; hexane-propan- 2-01 (19 :I), flow rate 1 cm3 min-'; t, (+)-29,25.0 min; (-)-29, 30.6 rnin].The racemate (k)-29 was prepared in 86% yield from racemate ( k )-28. (5s)-(+)-1-Benzyl-5-heptyl- 1,5-dihydropyrro1-2-one 25 by Heating of Compound 29 in Xylenex-A solution of tricycle 29 (86mg, 0.26 mmol) in xylenes (3 cm3) was heated at reflux for 35 min. The reaction mixture was charged directly to a silica column. Elution with hexane+thyl acetate (1 :0+3 : 1) gave compound 25 (49 mg, 71%); +58.8 (c 0.8, CHCl,), e.e.>,97%. This compound was further transformed into the saturated lactam (-)-24 -19.3 (c 0.5, CH,Cl,)} by hydrogen- ation, as described above. (-)-1-Benzyl-5-heptylpyrrolidine-2-thione30.-A solution of (-)-24 -19.3 (c 0.5, CH,Cl,), 14 mg x mol} and Lawesson's reagent (12.4 mg, 3.1 x lop5 mol) in dry benzene (5 cm3) was heated at reflux for 1.5 h under a hood. The solvent was evaporated and the residue (31 mg) was purified by chromatography on silica with hexane-ethyl-acetate (10 :1) to give compound 30 '*(14 mg, 94%) as an oil; -145.5 (c 0.44, EtOH) {lit.," -107.1 (c 1.3, EtOH)}. The e.e. of product (-)-30 was estimated 393% by chiral HPLC [Chiralpak AS; hexane-propan-2-01 (40: I), flow rate 0.5 cm3 min-'; tR (-)-30, 29.6 min; (+)-30, 23.9 min].X-Ray Crystallography.-Compound 4c: C26H31N04S,M = 453.6, monoclinic, space group El,,a = 14.917(2), b = J. CHEM. SOC. PERKIN TRANS. I 1994 7.129(1), c = 11.137(2) A, /?= 98.20(1)", 2 = 2, V = 1172.2(3) A3,D, = 1.285 g ~m-~, p(Cu-Ka) = 14.6 cm-', crystal size = 0.3 x 0.07 x O.Oz3, number of reflections (28 d 110") = 1569, R = 0.042 for 1404 reflections with F, > 3a(F,). Compound 6c:C,,H2,N05S, M = 455.6, monoclinic, space group P2,, a = 9.742(1), b = 16.703(3), c = 7.041(2) A, = 92.39(2)0, Z = 2, V = 1144.7(4) A3, D,= 1.322 g ~m-~,p(Cu-Ka) = 15.3 cm-', crystal size = 0.5 x 0.05 x 0.05 mm3, number of reflections (28 < 110") = 1499, R = 0.051 for 975 reflections with F, > 3a(F0).Intensity data were collected on a Rigaku AFC-5R diffractometer in w-28 scan mode using Cu-Ka radiation (2 = 1.541 78 A). The structures were solved by use of the program of MULTAN3' and were refined by the block-diagonal least- squares method for the positional parameters of all the atoms, using anisotropic thermal parameters of the non-hydrogen atoms. 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ISSN:1472-7781
DOI:10.1039/P19940000025
出版商:RSC
年代:1994
数据来源: RSC