A direct and selective syntheses of alpha,alpha-dichloro- and alpha-chloro-ethyl ketones by the reaction of alkyl carboxylates with 1,1-dichloroethyllithium

1,1-Dichloroethyllithium (5), generated by treating 1,1-dichloroethane (4) with lithium diisopropylamide (LDA) or n-butyllithium, reacted with alkyl c arboxylates to afford the corresponding alpha,alpha-dichloro- or alpha-mono chloro-ethyl ketones selectively in good to high yields. According to the a bove alkylation method, synthetic intermediates of Taxol, optically active alpha,alpha-dichloroethyl polyoxyketone 2 and alpha-chloroethyl polyoxyketo ne 3, were respectively synthesized from optically active methyl polyoxycar boxylate 1 in good yields.