Intramolecular palladium(0)-catalyzed coupling of enol triflate and vinylstannane functions. New annulation sequences leading to bicyclic diene systems

Abstract

A new, concise annulation method leading to the efficient production of structurally novel bicyclic dienes has been developed. The individual synthetic steps that constitute this method, as outlined in general terms in Scheme 1, involve (a) the alkylation of (functionalized) carbonyl compounds with ε{lunate}-iodo-2-trimethylstannyl-1-alkenes (17 → 21), (b) the conversion of the alkylatlon products into the corresponding enol trifluoromethanesulfonates (triflates) (21 → 22), and (c) the palladlum(0)-catalyzed intramolecular coupling of the enol triflate-vinylstannanes to provide the dienes (22 → 23). The generality of the method is demonstrated by the synthesis of functionalized bicyclo(4.3.0]nonane (61, 62, 65, 66), bicyclo[4.4.0]decane (63, 64, 67, 68, 71), bicyclo[5.3.0]decane (70), and bicyclo[5.4.0]undecane (69) derivatives. © 1991.