FORMATION AND ALKYLATION OF (TRIMETHYLSILYL)-DICHLOROMETHYLLITHIUM, (PHENYLDIMETHYLSILYL)-DICHLOROMETHYLLITHIUM, AND (DIPHENYLMETHYLSILYL)-DICHLOROMETHYLLITHIUM - PREPARATION OF ALPHA,ALPHA-DICHLOROALKYLSILANES AND ((Z)-1-CHLORO-1-ALKENYL)-SILANES

(Dichlorometyl)trimethylsilane, Me3SiCCl2H, (dichloromethyl)phenyldimethylsilane, PhMe2SiCCl2H, and (dichloromethyl)diphenylmethylsilane, Ph2MeSiCCl2H, readily react with lithium diisopropylamide in THF at -78°C to from the corresponding α-silyldichloromethyllithium reagents. The relative stability of the lithium reagents at -78°C is Ph2MeSiCCl2Li~PhMe2SiCCl2Li > > Me3SiCCl2Li. All three of the lithium reagents are readily silylated with chlorosilanes or alkylated with primary bromides and iodides. The α,α-dichloroalkylsilanes formed from the alkylation are stereoselectively dehydrochlorinated in refluxing dimethylformamide to ((Z)-1-chloro-alkenyl)silanes. © 1979.