A silicon-position dependent 6-endo-trig cyclization during Tsuji-Trost alkylation

Two silylated cyclohexenes products have been prepared by using a Tsuji-Trost palladium-catalyzed cyclization. It involves the generation of a cationic π-allylic palladium complex bearing a triethylsilyl group on C-3, which cyclizes via a 6-endo-trig process to afford the cyclohexene derivatives. It is also demonstrated that the position of the silyl group on the starting allylic substrate strongly influenced the reaction. It could favor either the production of the expected cyclohexenyl ring or a diene by an elimination that occurs on the silyl-substituted C-2 π-allylic palladium complex.