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Intramolecular hydroamination of alkynes catalysed by late transition metals |
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Dalton Transactions,
Volume 1,
Issue 4,
1999,
Page 583-588
Thomas E. Müller,
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摘要:
DALTON FULL PAPER J. Chem. Soc. Dalton Trans. 1999 583–587 583 Intramolecular hydroamination of alkynes catalysed by late transition metals Thomas E. Müller * and Anna-Katharina Pleier Institut für Technische Chemie II Technische Universität München Lichtenbergstraße 4 85747 Garching Germany. E-mail tmuller@ibm.net Received 16th November 1998 Accepted 15th December 1998 The cyclisation of 6-aminohex-1-yne to 2-methyl-1,2-dehydropiperidine in the presence of late transition metal catalysts was examined. The highest catalytic activity was observed for [Cu(CH3CN)4]PF6 as well as with Group 12 metal salts. Slightly lower conversions were obtained with the rhodium(I) and palladium(II) complexes [Rh(COD)(DiPAMP)]BF4 and [Pd(Triphos)][BF4]2. Catalysis was also observed with complexes of all group 9 to 12 metals and [Ru3(CO)12].All catalytically active complexes contain a metal with a d8 or d10 electronic configuration. This observation allows preliminary conclusions about the mechanism to be made. Introduction The direct addition of amine H–N bonds to alkenes and alkynes is an eYcient method of carbon–nitrogen bond construction and provides a direct route to a variety of molecules containing an amine functionality. Although the corresponding addition of alcohol H–OR bonds to alkenes and alkynes has been known for a long time additions of amines to alkenes and alkynes are rare.1–3 Thermodynamic considerations indicate that the direct addition of amines to alkenes is approximately thermoneutral.4–6 Although hydroamination of alkynes is thermodynamically more favourable the reaction is hampered by a high activation barrier.Promoting the reaction by high temperatures is limited as the entropy is negative. Consequently catalysis at relatively low temperatures is required. Catalysts based on early transition metals especially zirconium 7 lanthanide metals 8–10 and actinide metals,11 have recently been developed. Mechanistic investigations have shown that catalysis with early transition metals often involves activation of the amine by co-ordination to the metal.7–11 The key step of the catalytic cycle is the insertion of the carbon– carbon double or triple bond into the M–N bond. In contrast examples for the direct addition of amines to alkenes and alkynes using late transition metal catalysts are rare. Tethered aminoalkynes have been cyclised using nickel,12 palladium 13,14 and gold14 complexes as catalysts.Moderate activity of the catalysts requires 3–5 mol% of the complexes (turnover number TON = 13–22). Compared to an intramolecular reaction the intermolecular addition of amines to alkynes is thermodynamically less favoured. Therefore stoichiometric use of transition metal complexes as promoters is generally required. The most established synthetic route is the aminomercuration–demercuration sequence.15 This method can be made catalytic by appropriate choice of the reaction conditions although catalytic eYciency remains low (TON = 8–14).16 We now report that various complexes of Group 8 to 12 metals eVectively catalyse the intramolecular addition of amines to alkynes.17,18 Major factors aVecting the catalytic activity of late transition metal complexes for the addition of amines to alkynes are discussed.Special focus is given to the oxidation state of the metal centre as mechanistic conclusions can be drawn from it. Results and discussion The catalytic activity of various complexes for the direct addition of amines to alkynes is compared for the cyclisation of 6-aminohex-1-yne 1. The cyclisation of 1 with 1 mol% of the appropriate transition metal complex first generates 2- methylenepiperidine 2 with an exocyclic double bond. Subsequent 1,3-hydrogen shift converts the enamine into the more stable isomeric imine 2-methyl-1,2-dehydropiperidine 3 [eqn. (1)]. Close to quantitative conversions were observed for the copper(I) compound [Cu(CH3CN)4]PF6 and Group 12 metal salts like Zn(O3SCF3)2 Cd(NO3)2?4H2O and Hg(NO3)2? H2O (see Table 1).Slightly less active are the rhodium(I) and palladium(II) complexes [Rh(COD)(DiPAMP)]BF4 DiPAMP = 1,2-bis[(o-methoxyphenyl)(phenyl)phosphino]ethane (80% conversion) and [Pd(Triphos)][BF4]2 Triphos = bis(diphenylphosphinoethyl) phenylphosphine (83% conversion). A 44% conversion of 1 was observed when the silver(I) salt AgBF4 was employed at room temperature using CH2Cl2 as solvent. Catalysis with noble metal salts without co-ordinating ligands is hampered by their poor stability. During catalysis employing AgBF4 in CH2Cl2 AuCl3 in CH2Cl2 AuCl3 in CH3CN or [Pd(CH3CN)4][BF4]2 in CH3CN at reflux temperature the metal salts decomposed to varying degrees although catalytic activity was still observed (51 34 57 and 83% conversion respectively). In order to increase the stability of noble metal salts as catalysts phosphines were added.Use of bidentate phosphines however leads to a dramatic drop in catalytic activity e.g. with [Pd(dppf)][NO3]2 only 5% conversion of 1 was observed. In contrast with Triphos as tridentate ligand the metal complexes were catalytically active although under comparable conditions the complexes Mn1(Triphos)(X2)n Mn1 = Ag1 Au31 or Pd21 X2 = BF4 2 Cl2 or BF4 2 respectively were not as active as the corresponding salts of the naked metal. The good thermal stability of the complexes Mn1(Triphos)- (X2)n allowed the use of higher temperatures without catalyst decomposition the best results being obtained using non-co- NH2 HN N H2C H3C H Cat. 1 3 2 (1) 584 J. Chem. Soc. Dalton Trans. 1999 583–587 Table 1 Cyclisation of 6-aminohex-1-yne with Group 8 to 12 transition metal catalysts Group 8999 10 10 10 11 11 11 12 12 12 Metal Ruthenium(0) Cobalt(2I) Rhodium(I) Iridium(I) Nickel(0) Palladium(II) Platinum(II) Copper(I) Silver(I) Gold(III) Zinc(II) Cadmium(II) Mercury(II) Catalyst a [Ru3(CO)12] K[Co(CO)3(PPh3)] [Rh(COD)(DiPAMP)]BF4 [Ir(COD)(PCy3)(py)]PF6 [Ni(PPh3)4] [Pd(CH3CN)4][BF4]2 d [Pd(dppf)][NO3]2?CH2Cl2 [Pd(Triphos)][BF4]2?0.5CH3CN [Pd(Triphos)][BF4]2?0.5CH3CN [PtH(PEt3)2]NO3 [Cu(CH3CN)4]PF6 AgBF4 AgBF4 d [Ag(Triphos)]BF4 AuCl3 d AuCl3 d AuCl3–Triphos Zn(O3SCF3)2 Cd(NO3)2?4H2O Hg(NO3)2?H2O Solvent CH2Cl2 Toluene Toluene CH2Cl2 THF CH3CN CH2Cl2 Toluene Toluene CH2Cl2 CH3CN CH2Cl2 CH2Cl2 Toluene CH2Cl2 CH3CN CH2Cl2 Toluene CH3CN CH3CN T/8C 40 111 111 40 66 82 40 111 150 e 40 82 r.t.40 111 40 82 40 111 82 82 Yield b (%) 21 66 59 76 40 67 77 52 67 42 93 56 69 75 70 71 49 85 98 80 Conversion c (%) 18 2 80 42 28 83 5 69 93 29 100 44 51 26 34 57 14 100 98 100 a Mol ratios 1 catalyst = 100 1 time = 20 h.b Isolated yield of a mixture of 1?HCl and 3?HCl. c Determined by integration of the 1H NMR spectra of the mixtures 1?HCl and 3?HCl. d Some decomposition of the catalysts was observed. e Using a pressure tube. ordinating solvents. Thus conversions of 26 and 93% were obtained with the noble metal complexes [Ag(Triphos)]BF4 and [Pd(Triphos)][BF4]2 respectively. In general the cyclisation of compound 1 was achieved with complexes of all Group 9 to 12 metals and ruthenium. For a successful catalysis the valence state of the metal appears to be essential since no conversion of 1 was observed when complexes in diVerent oxidation states were employed.In contrast to the palladium(II) catalyst [Pd(Triphos)][BF4]2 no conversion was obtained with palladium(0) compounds like [Pd(PtBu3)2] [Pd(dppf)2] and the palladium dimer [Pd2Br2(PtBu3)4]. This is in accordance with the literature where a sharp increase in yield is reported for the cyclisation of a substituted 1-aminodec-3-yne with catalytic [Pd(PPh3)4] when the reaction mixture was left open to air.13 Similarly catalysis was observed with the rhodium( I) compound [Rh(COD)(DiPAMP)]BF4 but not with the rhodium(III) complex [RhI2(COD)]Cl. Another example is the activity of the gold(III) catalyst AuCl3–Triphos (14% conversion) which is in contrast to that of the gold(I) complex [AuCl(PPh3)] for which no conversion was observed.There was also no reaction when the complex [RuCl2(PPh3)2] [CoCp- (CO)2] or [Ni(PPh3)2][NO3]2 was employed whereas a moderate catalytic activity was observed with the following ruthenium(0) cobalt(2I) and nickel(0) complexes [Ru3(CO)12] K[Co- (CO)3(PPh3)] and [Ni(PPh3)4] (18 2 and 28% conversion). Considering the oxidation state of the catalytically active metal compounds the following rules can be formulated (Scheme 1) (i) transition metals in the fourth period are catalytically active if they have a d10 electronic configuration (Co2I Ni0 CuI ZnII); (ii) elements in the fifth period found to the right of palladium are active with a d10 electronic configuration (AgI CdII) whereas palladium and elements to the left are catalytically active if they have a d8 electronic configuration (Ru0 RhI PdII); (iii) elements in the sixth period are catalytically active only with a d8 electronic configuration (IrI PtII AuIII) except mercury which is active with a d10 electronic configuration (HgII).Scheme 1 Oxidation states of the catalytically active metals. Group 8 Group 9 Group 10 Group 11 Group 12 Co–I RhI IrI Ni0 PdII PtII CuI AgI AuIII ZnII CdII HgII Ru0 From these observations a number of mechanistic conclusions can be drawn. Common for all catalytically active complexes is that they are rather electron rich compounds. The metals with d10 electronic configuration especially ZnII and CuI can be described as typical Lewis acids. This suggests a mechanism where the transition metal activates the alkyne toward nucleophilic attack by the amine rather than one involving oxidative addition of the N–H bond to the metal.The metals with d8 electronic configuration especially IrI and PtII can act either as Lewis acids or as Lewis bases. However a mechanism based on the activation of the amine by oxidative addition of the amine to the metal centre requires a metal which can increase its oxidation state by two more units. Since it was demonstrated that for the redox pairs Pd0/PdII and AuI/AuIII only those complexes display catalytic activity which contain the metal in the higher oxidation state a mechanistic cycle for the hydroamination of alkynes cannot involve an oxidative addition of the amine to the metal centre. Support for this conclusion comes from the fact that for copper(I) and silver(I) only the increase of oxidation state by one unit is possible under normal conditions and no other oxidation state is available for zinc(II) during a catalytic cycle.Since copper(I) zinc(II) and silver(I) salts have been shown to be good catalysts for the cyclisation of compound 1 the reaction cannot involve a change of oxidation state at the metal centre. For the redox pairs Ru0/RuII RhI/RhIII and Ni0/NiII where catalytic activity was observed only for those complexes which contain the metal in the lower oxidation state a mechanism via an oxidative addition to the metal centre cannot be excluded. However the experimental results indicate that the same mechanism is valid for all metal complexes described here. Most of the noble metal complexes mentioned have a square planar geometry. Typical examples for this geometry are [Rh(COD)(DiPAMP)]BF4 [Ir(COD)(PCy3)(py)]PF6 and Mn1- (Triphos)(X2)n.The high catalytic activity of the complexes with tridentate phosphines indicates that only one co-ordination site is required for catalysis. If no change of oxidation state occurs during catalysis the overall square planar co-ordination of the metal might be maintained throughout the catalytic cycle. However a ligand exchange which proceeds via the coordination of a further ligand resulting in a five-co-ordinate transition state 19 cannot be excluded. With the aim of obtaining further insights into the mechanism the triply deuteriated substrate DC]] ] C(CH2)4ND2 was cyclised with various catalysts. The product was isolated J. Chem. Soc. Dalton Trans. 1999 583–587 585 together with the remaining starting material as the hydrochlorides and 1H and 13C-{1H} NMR spectra taken of the mixture.For each catalyst the spectra were identical except for the relative intensities of the signals assigned to the deuteriated starting material d3-1?HCl and product d3-3?HCl. Closer inspection of the 13C-{1H} NMR signals of 3?HCl reveals that in three positions they are split due to C–D coupling. A quintet at d 24.4 is assigned to the methyl group attached to C2 with the approximate substitution CHD2 a triplet at d 31.7 to the methylene group at C3 with the substitution CHD (Scheme 2). A further triplet at d 17.8 is assigned to the methylene group at C4 the signal being split by coupling with the deuterium atoms at C3. The assignment is confirmed by the smaller coupling constant 2J(13C 2D) = 10 Hz for the signal at d 17.8 in comparison to 1J(13C 2D) = 20 Hz for the multiplets at d 31.7 and 24.4.Integration of the 1H NMR spectrum of the deuteriated product d3-3?HCl gives 1.4 proton for the methyl group and 1.0 proton for the methylene group at C3 (Scheme 2). From this 1.6 deuterium atoms are calculated for the methyl group and 1.0 deuterium atom for the methylene group. The same ratio of protons to deuterium is observed for all catalysts employed including [Ir(COD)(PCy3)(py)]PF6 [Ni(PPh3)4] [Pd(CH3- CN)4][BF4]2 and AgBF4. Within the statistical error these numbers agree with a random distribution of the three deuterium atoms over the methyl group and the methylene group at C3 which is calculated as in eqn. (2) and (3) with n = number Methyl group n × n(D) n(H 1 D) × a = 3 × 3 5 × 0.8 = 1.4D (2) Methylene group n × n(D) n(H 1 D) × a = 2 × 3 5 × 0.8 = 1.0D (3) of positions in each group n(D) = total number of deuterium atoms involved n(H 1 D) = sum of protons and deuterium atoms involved.For a starting material with the three acidic protons completely exchanged by deuterium (a = 1.0) a ratio H:D of 0.8 1.2 and 1.2 1.8 is calculated for the methylene and the methyl group respectively whereas for the partially deuteriated starting material used (a = 0.8) a ratio H :D of 1.6 1.4 and 1.0 1.0 is calculated. From the experimental results described and their discussion a mechanism can be proposed. It will be described using the cyclisation of DC]] ] C(CH2)4ND2 with [Pd(Triphos)][BF4]2 as an example (Scheme 3). In the first step the substrate is coordinated to the empty site in the cationic complex Pd(PPP)21 via the triple bond.An equilibrium exists where the substrate is co-ordinated via the amine functionality but does not lead to further reactions. Co-ordination of p(C]] ] C) to the palladium centre activates the triple bond for a nucleophilic attack of the free electron pair on nitrogen. The formation of the carbon– nitrogen bond is accompanied by the formation of a palladium–carbon single bond which is then protonated quickly and irreversibly. The intermediate product d3-2 is formed but is likely to remain co-ordinated to the palladium either via the double bond or the nitrogen or both. Co- Scheme 2 Cyclisation of DC]] ] C(CH2)4ND2 with various catalysts. ND2 DHC N D2HC D 2 4 3 Me Distribution of deuterium in the product Position Experiment Calculated Methyl group Methlene group (C3) 1.4H 1.6D 1.6H 1.4D 1.0H 1.0D 1.0H 1.0D ordination of d3-2 to the palladium centre favours a shift of the C]] C double bond from the exocyclic position to an endocyclic position.A further reversible reaction is the formal [1,3] shift of the remaining deuterium on the nitrogen atom and formation of the more stable imine d3-3. Elimination of d3-3 from the co-ordination sphere of the palladium closes the catalytic cycle. In the mechanistic cycle proposed a number of formal [1,3]- hydrogen shifts were mentioned. However the orbital symmetry does not allow the geometrically easy [1,3] suprafacial shift of hydrogen atoms.20,21 Intramolecular reactions of this type are virtually unknown. Therefore intermolecular reactions are postulated in order to account for the hydrogen shifts observed.The shift of the double bond from the exocyclic position to the endocyclic position as well as the formation of the imine probably involves deprotonation in the a position which is facilitated by co-ordination of the substrate to the palladium.22 An intermediate allyl complex is postulated which can easily be protonated to give the product of a formal [1,3]- hydrogen shift. Conclusion The aminoalkyne 1 can be eYciently converted into the cyclic imine 3 with a series of transition metal catalysts. The most active catalysts are the copper(I) compound [Cu(CH3CN)4]PF6 and Group 12 metal salts. Turnover numbers close to the theoretical limit (up to 96) have been achieved which is much higher than previously known. Slightly less active are the rhodium(I) and palladium(II) complexes [Rh(COD)(DiPAMP)]BF4 and [Pd(Triphos)][BF4]2.The connection between the oxidation state of the transition metal i.e. number of d electrons and the catalytic properties was demonstrated. The trends observed lead to a prediction of catalytic activity and enable a more rational choice of compounds as new catalysts for the hydroamination of alkynes. Preliminary mechanistic studies indicate a common pathway for the intramolecular hydroamination of alkynes with all the late transition metal complexes investigated and a plausible mechanism is proposed. Current work in our laboratories is aimed at further investigating the mechanism as well as to explore the preparative scope of the cyclisation of aminoalkynes. Experimental Materials and methods All reactions involving air- and/or water-sensitive compounds were performed using standard Schlenk techniques.Solvents were obtained dry from Aldrich except thf which was dried over KH and distilled prior to use. Catalysts and other chemicals were purchased from Aldrich [Cu(CH3CN)4]PF6 [Pd(CH3CN)4][BF4]2 Fluka AgBF4 Hg(NO3)2?H2O and Strem [Ir(COD)(PCy3)(py)]PF6 [Rh(COD)(DiPAMP)]BF4 Zn(O3SCF3)2 and used as received. Professor W. A. Herrmann is thanked for a gift of AuCl3 and Cd(NO3)2?4H2O Dr. P. Dyson for [Ru3(CO)12] and Dr. R. Vilar for [Pd(PtBu3)2] and [Pd2- Br2(PtBu3)4]. The salt K[Co(CO)3(PPh3)] 23 was prepared as described. Physical and analytical methods The 1H 13C and 31P NMR spectra were recorded on a Bruker AM 400 spectrometer and referenced in ppm relative to the solvent shift 24 or tetramethylsilane infrared spectra on a Perkin-Elmer 1600 spectrometer as KBr discs if not stated otherwise and mass spectra on a Finnigan MAT 311A instrument by chemical ionisation (CI) or the fast atom bombardment (FAB) method.Elemental analyses were performed by the Microanalytical Laboratory of the Technische Universität München. 586 J. Chem. Soc. Dalton Trans. 1999 583–587 Scheme 3 Mechanism proposed for the intramolecular hydroamination of DC]] ] C(CH2)4ND2 with the palladium catalyst [Pd(Triphos)][BF4]2 (h represents an empty co-ordination site). PhP Pd2+ PPh2 PPh2 D ND2 PhP Pd+ PPh2 PPh2 N+ D2 D ND D2C ND D2HC TriphosPd2+ TriphosPd2+ PhP Pd2+ PPh2 PPh2 N CHD CHD2 PhP Pd2+ PPh2 PPh2 N Me ND2 D PhP Pd2+ PPh2 PPh2 D ND2 H/D = 0.8/1.2 H/D = 1.2/1.8 ± H/D ± D ± H/D Preparations H2N(CH2)4C]] ] CH.5-Cyanopent-1-yne (0.269 mol 25.0 g) was dissolved in Et2O (100 cm3) and added over a period of 60 min to a magnetically stirred mixture of 0.289 mol LiAlH4 (11.0 g) in Et2O (400 cm3) at 08C. The mixture was refluxed overnight the excess of LiAlH4 destroyed by addition of 75 cm3 water the mixture filtered and the organic layer separated. The Et2O was removed to yield a yellow liquid. Addition of 300 cm3 1 M HCl in Et2O (0.300 mol) precipitated the product as the hydrochloride which was filtered oV and dried in vacuo. The hydrochloride (23.3 g) was dissolved in methanol (100 cm3) 18.5 g Na2CO3 (0.175 mol) were added and the mixture stirred at room temperature for 1 h. The solvent was removed and the product distilled (69–70 8C at 18 mmHg).Yield 10.6 g 41% (Found C 74.3; H 11.4; N 14.2. Calc. for C6H11N C 74.2; H 11.3; N 14.4%). d = 0.852 g cm23. 13C-{1H} NMR (CDCl3) d 84.3 (s C2) 68.4 (s C1) 41.7 (s C6) 32.8 (s C5) 25.8 (s C4) and 18.3 (s C3). 1H NMR (CDCl3) d 2.72 (t 2 H CH2N) 2.22 (td 2 H CH2C]] ] C) 1.96 (t 1 H HC]] ] C) variable 1.9–1.6 (m 2 H NH2) and 1.57 (m 4 H CH2CH2). m/z (CI) 98 (M1 1 1). IR (film) 3295vs 2934vs 2862s 2115m 1596s 1455s 1392w 1328w 1037s 943w 896w and 635s cm21. H2N(CH2)4C]] ] CH?HCl. 6-Aminohex-1-yne (100 ml 0.88 mmol) was dissolved in Et2O 5 cm3 1 M HCl in Et2O (5 mmol) were added and the solvent removed in vacuo. Yield 10.6 mg 91% (Found C 53.9; H 9.0; Cl 26.3; N 10.4. Calc. for C6H13ClN C 53.9; H 9.0; Cl 26.6; N 10.5%). 13C-{1H} NMR (CD3OD) d 84.1 (s C2) 70.4 (s C1) 40.3 (s C6) 27.5 (s C5) 26.4 (s C4) and 18.6 (s C3).1H NMR (CD3OD) d 4.8 (s 3 H NH3 1) 2.96 (t 2 H CH2N) 2.27 (m 1 H HC]] ] C) 2.25 (m 2 H CH2C]] ] C) 1.80 (qnt 2 H CH2CN) and 1.60 (qnt 2 H CH2CC]] ] C). m/z (FAB) 98 (M1 2 Cl). IR 3228vs 3094vs 2981vs 2892vs 2722m 1609s 1490s 1466s 988s 880m 778s 715s 684s and 416s cm21. D2N(CH2)4C]] ] CD?HCl. 13C-{1H} NMR (CD3OD) d 83.6 [t C2 1J(13C 2D) = 7] 70.1 [t C1 1J(13C 2D) = 38 Hz] 40.3 (s C6) 27.5 (s C5) 26.4 (s C4) 18.6 (s C3). 1H NMR (CD3OD) d 4.8 [s 1.4 H N(H/D)3 1] 2.96 (t 2 H CH2N) 2.27 (m 0.2 H H/DC]] ] C) 2.25 (m 2 H CH2C]] ] C) 1.80 (qnt 2 H CH2CN) and 1.60 (qnt 2 H CH2CC]] ] C). Catalysis and hydrochloride of 2-methyl-1,2-dehydropiperidine. In a typical procedure a mixture of 6-aminohex-1- yne (0.10 cm3 0.88 mmol) [Cu(CH3CN)4]PF6 (3.2 mg 8.8 mmol) and acetonitrile (25 cm3) was heated at reflux for 20 h.The product 2-methyl-1,2-dehydropiperidine was isolated together with the remaining starting material as a mixture of hydrochlorides (0.11 g 93% yield). The product distribution was analysed by 1H NMR spectroscopy using the following signals for the integration at d 3.0 2.3 and 1.6 for the starting material and at d 3.6 2.8 and 2.4 for the product. For [Cu- (CH3CN)4]PF6 a quantitative conversion into the product was observed (Found C 53.5; H 9.1; H 10.4. Calc. for C6H12ClN C 53.9; H 9.1; H 10.5%). 13C-{1H} NMR (CD3OD) d 191.8 (s C2) 45.7 (s C6) 32.1 (s C3) 24.9 (s Me) 20.2 (s C5) and 17.9 (s C4). 1H NMR (CD3OD) d 4.8 (s 1 H NH1) 3.64 (s 2 H CH2N) 2.83 (t 2 H CH2C]] N) 2.39 (s 3 H Me) 1.89 (m 2 H CH2CC]] N) and 1.85 (m 2 H CH2CN).m/z (FAB) 98 (M1 2 Cl). IR 2960s 2876s 1696vs 1637s 1450s 1026s cm21. Hydrochoride of 2-methyl-1,2-dehydropiperidine-d3. 13C-{1H} NMR (CD3OD) d 191.8 (s C2) 45.7 (s C6) 31.7 [t C3 1J(13C 2D) = 20] 24.4 [qnt Me 1J(13C 2D) = 21] 20.2 (s C5) and 17.8 [t C4 2J(13C 2D) = 10 Hz]. 1H NMR (CD3OD) d 4.8 (s 1 H NH1) 3.64 (s 2 H CH2N) 2.83 [t 1.0 H C(H/D)2C]] N] 2.39 (s 1.4 H Me) 1.89 (m 2 H CH2CC]] N) and 1.85 (m 2 H CH2CN). [Ag(Triphos)]BF4. The compound Triphos (0.47 mmol 0.25 g) was dissolved in CH2Cl2 (20 cm3) and added to a magnetic- J. Chem. Soc. Dalton Trans. 1999 583–587 587 ally stirred solution of 0.47 mmol AgBF4 (92 mg) in CH2Cl2 (100 cm3). The solution was filtered the volume reduced in a partial vacuum and the product precipitated with pentane. The product was recrystallised from CH2Cl2–pentane and dried in vacuo.Yield 0.32 g 93% (Found C 55.4; H 4.6. Calc. for C34H33AgBF4P3 C 56.0; H 4.6%). 31P-{1H} NMR (CD3CN) d 5.9 (br 1P) 4.6 (br 1P) and 1.7 (br 1P). 13C-{1H} NMR (CD3CN) d 133.4–130.2 (mm Ph) 25.5 (m CH2) and 24.8 (m CH2). 1H NMR (CD3CN) d 7.4 2 7.2 (mm 25 H Ph) 2.4 (br 4 H CH2) and 2.2 (br 4 H CH2). m/z (FAB) 641 (M1 2 BF4). IR 3053m 1482m 1435s 1084vs (BF4 2) 742s 695s and 511m cm21. AuCl3–Triphos. The compound Triphos (0.470 mmol 0.251 g) was dissolved in CH2Cl2 (15 cm3) and added to a magnetically stirred solution of 0.470 mmol AuCl3 (0.143 g) in CH2Cl2 (50 cm3). The volume was increased to 100 cm3 and 1.9 cm3 of the solution used for catalysis. Ni(PPh3)4. The complex Ni(COD)2 (8.8 mmol 2.4 mg) was dissolved in thf (5 cm3) 35 mmol PPh3 (9.2 mg) were added the solution filtered and the volatiles removed.The remaining solid was dried in vacuo and used without further characterisation. [Pd(dppf)][NO3]2?CH2Cl2. The compound dppf (0.35 mmol 0.19 g) was dissolved in CH2Cl2 (5 cm3) and added to a magnetically stirred solution of 0.35 mmol [PdCl2(COD)] (0.10 g) in CH2Cl2 (25 cm3). The solvent was removed and the residue dried in vacuo. The solid was redissolved in CH2Cl2 (15 cm3) and a solution of 0.70 mmol AgNO3 (0.12 g) in MeOH (35 cm3) added. The resulting suspension was stirred for 1 h in the dark and filtered over Celite. The filtrate was taken to dryness the residue recrystallised from CH2Cl2–MeOH (3 1)–Et2O and dried in vacuo. Yield 0.23 g 83% (Found C 48.3; H 3.5; N 3.2. Calc. for C35H30Cl2FeN2O6P2Pd C 48.3; H 3.5; N 3.2%).31P-{1H} NMR (CDCl3–CD3CN 1 1) d 40.6 (s). 1H NMR (CDCl3–CD3CN 1 1) d 7.8 (br 8 H Ph) 7.7 (m 4 H Ph) 7.5 (s 8 H Ph) 5.4 (s 2 H CH2Cl2) 3.8 (s 4 H cp) and 3.3 (s 4 H cp). m/z (FAB) 722 (M1 2 NO3) and 660 (M1 2 2NO3). IR 3055w 1477vs 1436s 1384vs (NO3 2) 1275vs 1168w 1097m 1000m 749m 693m 558w 493m and 467m cm21. [Pd(Triphos)][BF4]2?0.5CH3CN. The compound Triphos (0.224 mmol 0.120 g) was dissolved in CH2Cl2 (20 cm3) and added to a magnetically stirred mixture of 0.224 mmol [Pd(CH3CN)4][BF4]2 (0.100 g) in CH2Cl2 (100 cm3). The mixture was stirred overnight filtered the volume reduced in a partial vacuum and the product precipitated with pentane. The product was recrystallised from CH2Cl2–pentane and dried in vacuo. Yield 0.120 g 64% (Found C 50.5; H 4.9; N 1.0. Calc. for C35H34.5B2F8N0.5P3Pd C 50.3; H 4.2; N 0.8%).31P-{1H} NMR (CD3CN) d 117.4 (s 1P) and 54.2 (s 2P). 13C-{1H} NMR (CD3CN) d 135.4s 134.6s 134.5s 134.0–133.7m 131.1– 130.7m 129.2s 128.5s 127.8s and 30.2 [d 2J(13C 31P) = 37 Hz] and 28.2s. 1H NMR (CD3OD) d 7.9 (dd 3 H) 7.7–7.5 (mm 22 H) 3.4 [dd 2 H 3J(1H 31P) = 54 Hz] 3.1 (br 2 H) 3.0 (m 2 H) 2.4 (br 2 H) and 2.1 (s 1.5 H CH3CN). m/z (FAB) 659 (M1 2 BF4 2 BF3) and 640 (M1 2 2BF4). IR 3053m 1436s 1084vs (BF4 2) 747s 692s 522s and 481m cm21. [PtH(PEt3)2]NO3. The complex [PtCl2(COD)] (0.815 mmol 0.305 g) was dissolved in 25 cm3 CH2Cl2 1.63 mmol PEt3 (1 M in thf 1.63 cm3) added and stirred for 10 min. Hexane (25 cm3) were added the volume reduced in a partial vacuum and the precipitate filtered oV. The solid was suspended in 20 cm3 hexane for 1 h.The product cis-[PtCl2(PEt3)2] was dried in vacuo dissolved in a mixture of 20 cm3 MeOH and 6.9 cm3 Et2NH; 0.82 mmol NaBH4 (31 mg) was added. After 10 min the volatiles were removed the residue extracted with pentane and the product [PtCl(H)(PEt3)2] isolated (0.13 g). The white powder was dissolved in 5 cm3 CH3CN 76.2 mg TlNO3 in a mixture of 2 cm3 water and 10 cm3 CH3CN added and the mixture stirred for 5 min. Filtration followed by removal of the solvent resulted in a white powder which was recystallised from pentane. Overall yield 69 mg 18% (Found C 29.1; H 6.3; N 2.7. Calc. for C12H31NO3PPt C 31.1; H 6.7; N 3.0%). 31P-{1H} NMR (C6D6) d 24.9 [t 2J(31P,195Pt) = 2819 Hz]. 13C-{1H} NMR (C6D6) d 18.0 (tt) and 8.4 (t). 1H NMR (C6D6) d 1.53 (m 12 H) 1.00 (qnt 18 H) and 0.39 (s 1 H).m/z (FAB) 431 (M1 2 NO3). IR 2962vs 2934s 2876s 2218s (Pt–H) 1448vs 1383vs (NO3 2) 1285vs 1051s 1020m 1002m 767vs and 696m cm21. Acknowledgements T. E. M. gratefully acknowledges funding as Liebig-Stipendiat by the Stiftung Stipendien-Fonds des Verbandes der Chemischen Industrie e.V. The Deutsche Forschungsgemeinschaft and Dr.-Ing. Leonhard-Lorenz-Stiftung are thanked for financial support. Daniel Käsmayr Dr. Carola Wagner and Erik Walter are thanked for their enthusiasm and their contribution to this project Dr. Gene Stark and Dr. Yaw-Kai Yan for proof reading the manuscript and last but not least Professor Matthias Beller for his support and many discussions. References 1 T. E. Müller and M. Beller Chem. Rev. 1998 98 675. 2 D. M. Roundhill Chem. Rev. 1992 92 1. 3 R. Taube in Applied Homogeneous Catalysis with Organometallic Compounds eds.B. Cornils and W. A. Herrmann VCH Weinheim 1996 vol. 1 p. 507. 4 D. Steinborn and R. Taube Z. Chem. 1986 26 349. 5 S. W. Benson Thermodynamical Kinetics Methods for the Estimation of Thermochemical Data and Rate Parameters 2nd edn. Wiley New York 1976. 6 J. B. Pedley R. D. Naylor and S. P. Kirby Thermochemical Data of Organic Compounds 2nd edn. Chapman and Hall London 1986 Appendix Table 1. 2. 7 A. M. Baranger P. J. Walsh and R. G. Bergman J. Am. Chem. Soc. 1993 115 2753. 8 M. R. Gagné C. L. Stern and T. J. Marks J. Am. Chem. Soc. 1992 114 275. 9 Y. Li and T. J. Marks J. Am. Chem. Soc. 1996 118 9295. 10 Y. Li and T. J. Marks Organometallics 1996 15 3770. 11 A. Haskel T. Straub and M. S. Eisen Organometallics 1996 15 3773. 12 E.M. Campi and W. R. Jackson J. Organomet. Chem. 1996 523 205. 13 K. Utimoto Pure Appl. Chem. 1983 55 1845. 14 Y. Fukuda K. Utimoto and H. Nozaki Heterocycles 1987 25 297. 15 J. Barluenga and F. Aznar Synthesis 1975 704. 16 J. Barluenga and F. Aznar J. Chem. Soc. Perkin Trans. 1 1980 2732. 17 T. E. Müller Tetrahedron Lett. 1998 39 5961. 18 T. E. Müller Ger. Pat. Appl. DE 19 816 479 1998. 19 J. P. Collmann L. S. Hegedus J. R. Norton and R. G. Finke Principles and Applications of Organotransition Metal Chemistry University Science Books Mill Valley CA 1987 vol. 4.4 p. 241. 20 I. Fleming Frontier Orbitals and Organic Chemical Reactions Wiley Chichester 1976 vol. 4.1.2.2 p. 98. 21 J. E. Baldwin and R. H. Fleming J. Am. Chem. Soc. 1972 94 2140. 22 R. B. Jordan Reaction Mechanisms of Inorganic and Organometallic Systems Oxford University Press 1998 vol. 4.5.e p. 125. 23 K. Inkrott R. Goetze and S. G. Shore J. Organomet. Chem. 1978 154 337. 24 H. E. Gottlieb V. Kotlyar and A. Nudelman J. Org. Chem. 1997 62 7512. Paper 8/08938H
ISSN:1477-9226
DOI:10.1039/a808938h
出版商:RSC
年代:1999
数据来源: RSC
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