Direct and selective syntheses of alpha,alpha-dichloroethyl ketones or their ethyl trimethylsilyl mixed acetals by the reactions of methoxymethyl or ethyl carboxylates with 1,1-dichloroethyllithium in the presence of chlorotrimethylsilane

1,1-Dichloroethyllithium (1), generated by treating 1,1 dichloroethane (2) with lithium diisopropylamide (LDA) or n-butyllithium, reacted with methoxy methyl carboxylates in the coexistence of chlorotrimethylsilane (3) to affo rd the corresponding alpha,alpha-dichloroethyl ketones in good yields. On t he other hand, 1 reacted with ethyl carboxylates under the above reaction c onditions to give 2,2-dichloro-1-alkyl-1-ethoxy-1-(trimethylsiloxy)propanes selectively in good yields.