Eschenmoser's salt

Eschenmoser's salt, dimethylmethylideneammonium iodide, is a strong dimethylaminomethylating agent, used to prepare derivatives of the type RCH₂N(CH₃)₂. Enolates, enolsilylethers, and even more acidic ketones undergo efficient dimethylaminomethylation. Once prepared, such tertiary amines can be further methylated and then subjected to base-induced elimination to afford methylenated ketones. The salt was first prepared by the group of Albert Eschenmoser after whom the reagent is named.

Analogous salts, dimethylmethylideneammonium chloride (Böhme's salt, after Horst Böhme) and trifluoroacetate, have similar properities and applications.