RuHCl(CO)(PPh3)3-Catalyzed α-Alkylation of Ketones with Primary Alcohols

The alpha-alkylation reaction of ketones with primary alcohols to give alpha-alkylated ketones was achieved using RuHCl(CO)(PPh3)(3) as a catalyst in the presence of Cs2CO3 as a base. This reaction proceeds via an aldol condensation of ketones with aldehydes, formed via transfer dehydrogenation of alcohols, to give alpha,beta-unsaturated ketones, which then undergo transfer hydrogenation with primary alcohols to give alpha-alkylated ketones and aldehydes, the latter of which participate in the next catalytic cycle. While the reaction of aliphatic primary alcohols was sluggish compared with that of benzylic alcohols, a catalytic amount of 1,10-phenanthroline was found to promote the alkylation dramatically.