Synthesis of carbobicyclic compounds via palladium-catalyzed cyclization/hydrosilylation: evidence for reversible silylpalladation

Cyclization/hydrosilylation of substituted 1-vinyl-1-(3-butenyl)cycloalkanes catalyzed by a 1:1 mixture of (phen)Pd(Me)Cl (1) and NaBAr(4) [phen = 1,10-phenanthroline; Ar = 3,5-C(6)H(3)(CF(3))(2)] formed silylated spirocycles in high yield with excellent regio and diastereoselectivity. Cyclization/hydrosilylation of substituted 3-(3-butenyl)cycloalkenes or 2,3-diallyl-5,6-dimethyl-1,4-hydroquinone diacetate (16) formed silylated fused bicyclic complexes in good yield. Reaction of substituted 1,6,11-nonatrienes with silane catalyzed by 1/NaBAr(4) led to cascade cyclization with hydrosilylation. This latter procedure was employed in the synthesis of silylated bicyclopentanes and a linear triquinane.