Homologative Trifluoromethylation of Acetals

We dedicate this manuscript to Prof. Dr. Scott E. Denmark in honor of his 60^th birthday.

Abstract

Trifluoroethyl α-insertion of acetals has been developed. Aromatic, heteroaromatic, and alkenyl acetals react with in situ generated­ (trifluoromethyl)diazomethane in the presence of antimony(V) chloride to furnish α-trifluoromethyl acetals. A stereoselective version of this transformation exploiting the acetal as a chiral auxiliary is also presented.

Key words

antimony - acetals - insertion - diazo compounds - trifluoromethyl group

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