Development of an anomalous heck reaction: Skeletal rearrangement of divinyl and enyne carbinols

Organic Letters

Volumn 7, Issue 26, 2005, Pages 5845-5848

  Ndungu, J Maina ^a   Larson, Kimberly K ^a   Sarpong, Richmond ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 30144440079     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol052382p     Document Type: Article

References (23)

1. Larhed, M.; Hallberg, A. In Handbook of Organopalladium Chemistry for Organic Synthesis; Negishi, E., Ed.; John Wiley and Sons: Hoboken, 2002; Vol. 1, pp 1133-1178.
2. (a) Scott, W. J.; Pena, M. R.; Swärd, K.; Stoessel, S. J.; Stille, J. K. J. Org. Chem. 1985, 50, 2302-2308.
3. (b) Cacchi, S.; Morera, E.; Ortar, G. Tetrahedron Lett. 1984, 25, 2271-2274.
4. Gribble, G. W.; Conway, S. C. Synth. Commun. 1992, 22, 2129-2141.
5. Iodobenzene and phenyl triflate react similarly to bromobenzene.
6. Only a trace amount of 9b was observed in this initial screen and in subsequent studies.
7. TMEDA has been shown to be a useful additive for preventing β-hydride elimination in other systems. See: Nakamura, M.; Matsuo, K.; Ito, S.; Nakamura, E. J. Am. Chem. Soc. 2004, 126, 3686-3687.
8. Although mixtures of TMEDA and Hünig's base did provide the desired products, thus supporting the necessity of Hünig's base, no increase in the amount of the anomalous Heck product was observed relative to entry 1.
9. Hills, I. D.; Netherton, M. R.; Fu, G. C. Angew. Chem., Int. Ed. 2003, 42, 5749-5752 and references therein.
10. Interestingly, ample precedent exists for the dramatic effect of quaternary ammonium salts on the efficiency of the standard Heck reaction as well. See: (a) Soderberg, B. C. In Comprehensive Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, NY, 1995; Vol. 12, Chapter 3.5, p 259.
11. (b) Bräse, S.; de Meijere, A. In Metal Catalyzed Coupling Reactions; Stang, P. J., Diederich, R, Eds.; John Wiley & Sons: New York, 1998 and references therein.
12. Other solvents that were examined include N-methyl pyrrolidone, dimethylimidazolidone, and acetonitrile.
13. See Supporting Information.
14. Our mechanistic proposal takes into consideration our observations of reactivity of both divinyl and enyne carbinols in the anomalous Heck reaction.
15. Coordination of hydroxyl functionality to cationic palladium intermediates during the vinylation of aryl triflates has been proposed previously and should predicate the stereochemistry indicated. See: (a) Oestreich, M.; Sempere-Culler, F.; Machotta, A. B. Angew. Chem., Int. Ed. 2005, 44, 149-152.
16. (b) Bernocchi, E.; Cacchi, S.; Ciattini, P. G.; Morera, E.; Ortar, G. Tetrahedron Lett. 1992, 33, 3073-3076.
17. 4NCl additive may serve to augment this effect, or the added halide might competitively bind to the metal center to further minimize β-hydride elimination.
18. (a) Owzarczyk, Z.; Lamaty, F.; Vawter, E. J.; Negishi, E.-i. J. Am. Chem. Soc. 1992, 114, 10091-10092.
19. See also: (b) Trost, B. M.; Dumas, J. Tetrahedron Lett. 1993, 34, 19-22.
20. (c) Brown, D.; Grigg, R.; Sridharan, V.; Tambyrajah, V.; Thornton-Pett, M. Tetrahedron 1998, 54, 2595-2606.
21. b bonds to provide an enol that tautomerizes to 15. The intermediacy of 15 is supported by the isolation of styrenyl products (see entry 5, Table 2).
22. b, readily undergo the anomalous Heck reaction to provide very good yields of the desired product. (Chemical Equation Presented) (19) The enal 9a was isomerized to a 3:1 E/Z mixture of olefin iosmers under photochemical irradiation (medium-pressure Hanovia Hg lamp), which when subjected to the reaction conditions readily reverts to 9a.
23. 1H NMR resonances using 1,2-dichloroethane as an internal standard.