Structural and mechanistic studies on the activation and propagation of a cationic allylpalladium procatalyst in 1,6-diene cycloisomerization

Chemistry - A European Journal

Volumn 7, Issue 19, 2001, Pages 4205-4215

  Bray, Katharine L ^a   Charmant, Jonathan P H ^a   Fairlamb, Ian J S ^a   Lloyd Jones, Guy C ^a  

^a UNIVERSITY OF BRISTOL   (United Kingdom)

Author keywords

Cyclization; Dienes; Isotopic labeling; Palladium

Indexed keywords

ACETONITRILE; CATALYSTS; ISOMERIZATION; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; OLEFINS; STEREOCHEMISTRY;

PROCATALYSTS;

PALLADIUM;

ALKADIENE; PALLADIUM;

ARTICLE; CATALYSIS; CYCLIZATION; ISOMERISM; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; SYNTHESIS; THERMODYNAMICS;

EID: 0035477778     PISSN: 09476539     EISSN: None     Source Type: Journal    
DOI: 10.1002/1521-3765(20011001)7:19<4205::AID-CHEM4205>3.0.CO;2-Q     Document Type: Article

References (73)

1. Reviews: a) B. M. Trost, Acc. Chem. Res. 1990, 23, 34-42;
2. b) B. M. Trost, M. J. Krische, Synlett 1998, 1-15.
3. A. Bright, J. F. Malone, J. K. Nicholson, J. Powell, B. L. Shaw, J. Chem. Soc. Chem. Commun. 1971, 712-713.
4. E. Schmitz, R. Urban, G. Zimmermann, J. Prakt. Chem. 1976, 318, 185;
5. E. Schmitz, U. Hench, D. Habisch, J. Prakt. Chem. 1976, 318, 471.
6. R. Grigg, T. R. B. Mitchell, A. Ramasubbu, J. Chem. Soc. Chem. Commun. 1979, 669-670.
7. R. Grigg, T. R. B. Mitchell, A. Ramasubbu, J. Chem. Soc. Chem. Commun. 1980, 27-28.
8. R. Grigg, J. F. Malone, T. R. B. Mitchell, A. Ramasubbu, R. M. Scott, J. Chem. Soc. Perkin Trans. 1 1984, 1745-1754.
9. a) W. E. Piers, P. J. Shapiro, E. E. Bunel, J. E. Bercaw, Synlett 1990, 74-84;
10. b) K. S. Knight, R. M. Waymouth, J. Am. Chem. Soc. 1991, 113, 6268-6270;
11. c) G. A. Molander, J. O. Hoberg, J. Am. Chem. Soc. 1992, 114, 3123-3126;
12. d) E.-I. Negishi, T. Takahashi, Acc. Chem. Res. 1994, 27, 124-130;
13. e) U. M. Dzhemilev, Tetrahedron 1995, 51, 4333-4346;
14. f) J. Christoffers, R. G. Bergman, J. Am. Chem. Soc. 1996, 118, 4715-4716;
15. g) S. Thiele, G. Erker, Chem. Ber./Recueil 1997, 130, 201-207;
16. h) S. Okamoto, T. Livinghouse, J. Am. Chem. Soc. 2000, 122, 1223-1224.
17. Y. Yamamoto, N. Ohkoshi, M. Kameda, K. Itoh, J. Org. Chem. 1999, 64, 2178-2179.
18. B. Radetich, T. V. RajanBabu, J. Am. Chem. Soc. 1998, 120, 8007-8008.
19. B. Bogdanovic, Adv. Organomet. Chem. 1979, 17, 104-140.
20. During the course of our investigations, a number of related papers were published by Widenhoefer et al.: a) R. A. Widenhoefer, N. S. Perch, Org. Lett. 1999, 1, 1103-1105;
21. b) P. Kisanga, R. A. Widenhoefer, J. Am. Chem. Soc. 2000, 122, 10017-10026;
22. c) N. M. Perch, R. A. Widenhoefer, J. Am. Chem. Soc. 1999, 121, 6960-6961;
23. d) N. M. Perch, P. Kisanga, R. A. Widenhoefer, Organometallics 2000, 19, 2541-2545;
24. e) P. Kisanga, L. A. Goj, R. A. Widenhoefer, J. Org. Chem. 2001, 66, 635-637;
25. f) Up to >90% ee has been achieved in the cycloisomerisation of 1a to 3a: R. A. Widenhoefer, personal communication.
26. a) A. Heumann, M. Moukhliss, Synlett 1998, 1211-1212;
27. b) K. L. Bray, I. J. S. Fairlamb, G. C. Lloyd-Jones, Chem. Commun. 2001, 187-188.
28. A. Fürstner, M. Liebl, C. W. Lehmann, M. Picquet, R. Kunz, C. Bruneau, D. Touchard, P. H. Dixneuf, Chem. Eur. J. 2000, 6, 1847-1857;
29. see also: B. Cetinkaya, S. Demir, I. Özdemir, L. Toupet, D. Sémeril, C. Bruneau, P. H. Dixneuf, New J. Chem. 2001, 25, 519-521.
30. G. C. Lloyd-Jones, Synlett 2001, 161-183.
31. K. L. Bray, G. C. Lloyd-Jones, Eur. J. Org. Chem. 2001, 1635-1642.
32. Detailed investigations into the mechanism by which simple neutral chloropalladium complexes effect highly selective cycloisomerisation of 1a to 3a (see ref. [12b]) will be reported in due course.
33. [11b] A recent study demonstrated the importance of the counterion with regard to the activity of these procatalysts: P. G. Cozzi, personal communication.
34. 2] (5 mol%) was completely inert as a catalyst for cycloisomerisation of 1a, even on prolonged heating (60°C).
35. 3 that had been freshly filtered through basic alumina, distilled and then degassed. Negligible conversion rates were observed at ambient temperature. However, after initiation of reaction (60°C, 30 min), slow turnover (72% conversion, 15 h; 2a, 3a, 4a obtained in 47:31:18 ratio) could be observed at 25°C. Pre-heating in the absence of 1a was not effective. Reaction at 40°C proved optimum for mechanistic studies in terms of rates and product ditributions. Reactions at 60°C proceeded more rapidly (>90%, 2 h), but generated large amounts of 4a (the thermodynamic product) through isomerisation of 2a and 3a.
36. After complete consumption of 1a, chromatography on silica gel afforded the cycloisomerisation product as an analytically pure mixture of double-bond isomers (2a, 3a and 4a).
37. 13C-labelled 4a.
38. a) G. Oehme, J. Prakt. Chem. 1984, 526, 779-790;
39. b) M. G. Barlow, M. J. Bryant, R. N. Haszeldine, A. G. Mackie, J. Organomet. Chem. 1970, 21, 215-226;
40. c) I. Guibert, D. Neibecker, I. Tkatchenko, J. Chem. Soc. Chem. Commun. 1989, 1850-1852;
41. d) G. Wilke, Angew. Chem. 1988, 100, 189-210;
42. Angew. Chem. Int. Ed. Engl. 1988, 27, 185-206;
43. e) G. M. DiRenzo, P. S. White, M. Brookhart, J. Am. Chem. Soc. 1996, 118, 6225-6234, and references therein;
44. f) S. J. McClain, J. Sanco, R. R. Schrock, J. Am. Chem. Soc. 1979, 101, 5451-5453.
45. For leading references and an overview from the perspective of organic chemists on the generation of "M-H", see B. M. Trost, Chem. Eur. J. 1998, 4, 2405-2412.
46. 2H exchange under CI conditions. Furthermore, since GC-MS was not available to us, we were unable to distinguish m/z peaks arising from isomeric alkenes (i.e., 1a from 2a, 3a and 4a).
47. 2H NMR).
48. 2H occurring through traces of water present in the reaction mixture.
49. 2H isotope shift (Δδ = 0.0175).
50. 2J(H,H) coupling is not observed (< 0.3 Hz).
51. 3.
52. 13C(2)) confirmed the earlier assignment of the E/Z methylene geometries in unlabelled 2a by NOED.
53. 3).
54. 2D) in both sets of C(5).
55. 3J(H,H) coupling to C(4)H.
56. A. Sen, T.-W. Lai, Organometallics 1983, 2, 1059-1060.
57. S. Mecking, W. Keim, Organometallics 1996, 15, 2650-2656.
58. Examples of reactions of cycloctadiene with cationic Pd - allyl species: a) R. R. Schrock, J. A. Osborn, J. Am. Chem. Soc. 1971, 93, 3089-3091;
59. b) B. F. G. Johnson, J. Lewis, D. A. White, J. Am. Chem. Soc. 1969, 91, 5186-5187.
60. +), the Pd atom is coordinated to the same enantioface of the two alkenyl groups. For a related and opposite example, see K. Nordström, C. Moberg, A. Heumann, J. Organometal. Chem. 1996, 525, 233-238.
61. A complete study of the solid (single-crystal X-ray diffraction) and solution-phase (NMR) structures of 15a and its reactivity towards a variety of ligands will be reported in due course: K. L. Bray, J. P. H. Charmant, I. J. S. Fairlamb, G. C. Lloyd-Jones, P. A. Slatford, unpublished results.
62. Note that other types of elimination have been documented: general-base-promoted anti-β-H elimination: a) P. G. Andersson, S. Schab, Organometallics 1995, 14, 1-2;
63. b) J. M. Tackacs, E. C. Lawson, F. Clement, J. Am. Chem. Soc. 1997, 119, 5956-5957;
64. specific-base-promoted syn-β-H elimination: c) D. R. Chrisope, P. Beak, W. H. Saunders, Jr., J. Am. Chem. Soc. 1988, 110, 230-238;
65. d) E. Keinan, S. Kumar, V. Dangur, J. Vaya, J. Am. Chem. Soc. 1994, 116, 11151-11152.
66. For a recent example of this effect, see S. Aït-Mohand, F. Hénin, J. Muzart, Organometallics 2001, 20, 1683-1686.
67. In asymmetric Pd-catalysed oxidative cyclisation reactions of a 1,5-diene, the presence of water was found to be crucial for selectivity: L. Tottie, P. Baeckström, C. Moberg, J. Tegenfeldt, A. Heumann, J. Org. Chem. 1992, 57, 6579-6587.
68. In a kinetic study of the Heck reaction, water was found to be involved in the activation process: T. Rosner, A. Pfaltz, D. G. Blackmond, J. Am. Chem. Soc. 2001, 123, 4621-4622 and references therein.
69. For a recent overview of some of the other remarkable effects that traces of water can have on organometallic systems, see S. Ribe, P. Wipf, Chem. Commun. 2001, 299-307.
70. [37].
71. Presumably due to the higher initial concentration of free MeCN, the reaction gave reasonable selectivity for the trisubstituted isomer 3a (ratios by GC, 2a/3a/4a: 9:75:16).
72. J. M. Brown, G. D. Hughes, Inorg. Chim. Acta 1996, 252, 229-237.
73. For example, see A. Takeda, S. Kamijo, Y. Yamamoto, J. Am. Chem. Soc. 2000, 122, 5662-5663.