Nucleophilic bromo- and iododifluoromethylation of aldehydes.

A method for bromo- and iododifluoromethylation of aldehydes using bromo- and iodo-substituted difluoromethyl silicon reagents (Me(3)SiCF(2)X) is described. The reaction is performed in the presence of a combination of tetrabutylammonium and lithium salts Bu(4)NX/LiX (X = Br or I) in propionitrile. It is believed that, in this process, a short-lived halodifluoromethyl carbanion serves as nucleophile, which is reversibly generated from difluorocarbene and a halide anion.