Mild Amide-Cleavage Reaction Mediated by Electrophilic Benzylation

摘要

An extremely mild method for amide-cleavage by using the triazine-based benzylating reagent 4-(4,6-diphenoxy-1,3,5-triazin-2-yl)-4-benzylmorpholinium trifluoromethanesulfonate (DPT-BM), which spontaneously releases benzyl cation species when being dissolved at room temperature, has been developed. O-Benzylation of the amide with DPTBM and the subsequent hydrolysis of the resulting intermediate benzyl imidate salt afford the corresponding amine and benzyl ester, which can be converted by hydrogenolysis into a carboxylic acid under neutral conditions. O-Benzylation proceeds depending on both steric and electronic factors around the amide group. Thus, some amides have been selectively cleaved over other amides. Furthermore, intramolecular chemoselective cleavage of an amide group in the presence of an ester group was achieved. Such selective hydrolytic reactions cannot be performed with Meerwein reagents as well as under acidic or basic hydrolytic conditions.