Borrowing Hydrogen in Water and Ionic Liquids: Iridium-Catalyzed Alkylation of Amines with Alcohols

The use of [Cp*IrI2](2) as an efficient catalyst for the alkylation of amines by alcohols in either water or ionic liquid is described. Primary amines are converted into secondary amines, and secondary amines into tertiary amines in the absence of base, and the chemistry has been applied to the synthesis of the analgesic fentanyl. The conversion of primary amines into N-heterocycles by the reaction with diols is also described, along with the N-alkylation of sulfonamides.