Tertiary Amine Synthesis via a Thiourea-Catalyzed Reductive Amination

Significance

A mild, acid- and metal-free reductive amination yielding tertiary amines has been reported. Thiourea is used as catalyst and a Hantzsch ester serves as hydrogen source in the transfer hydrogenation of in situ generated imines. This method is applicable for both primary and secondary amines; however, it is reported that the reaction proceeds directly to the tertiary amine starting from primary amines. Since ketones are much less reactive, it is possible to employ aldehydes that also contain a keto group as alkylating agents, giving the desired products in reasonable yields.