REGIOCHEMICALLY AND STEREOCHEMICALLY DEFINED SYNTHESIS OF ALLYLSILANES

Allyl sulfides containing a siloxy or hydroxy group at appropriate pos itions were successfully converted by two methods into two types of al lylsilanes with almost complete stereo- and regiocontrol. In one metho d, an allyllithium was generated from the siloxy compound after which the silyl group migrated from oxygen to the carbanionic site. The reac tion of trimethylsilyl)oxy]methyl]-3-methyl-2-cyclohexenyl phenyl sulf ide with lithium di-tert-butylbiphenylide (LDBB) led to an exclusive f ormation of ethyl-2-(trimethylsilyl)-3-cyclohexene-1-methanol. The sec ond method involved the silylation of an oxyanion-carbanion. Using thi s method, methyl-4-(trimethylsilyl)-2-cyclohexene-1-methanol was obtai ned by treating its lithium alkoxide with LDBB followed by silylation with chlorotrimethylsilane.