Triflic acid promoted direct α-alkylation of unactivated ketones using benzylic alcohols via in situ formed acetals.

Direct α-alkylation of unactivated ketones using benzylic alcohols as electrophiles has been achieved at room temperature. This reaction takes place via in situ formed acetal using triflic acid and trimethyl orthoformate. It is believed that methyl vinyl ether formed from the in situ generated dimethyl acetal in the presence of triflic acid undergoes alkylation. Diverse ketones could be alkylated with diarylmethanols, cinnamyl alcohols, and phenyl propargyl alcohols having different electrophilicities.