Chemoselective methylation of amides and heterocycles using chloromethyldimethylsilyl chloride

The reaction of chloromethyldimethylsilyl chloride with an amide generates a pentacoordinate N-(amidomethyl)-halosilane that can be desilylated with cesium fluoride to give the N-methyl amide. This provides a selective method for the monoalkylation of amides in the presence of other, more nucleophilic groups.