Aza-Henry reaction of ketimines catalyzed by guanidine and phosphazene bases

A general catalytic addition of nitromethane to simple N-diphenylphosphinoyl ketimines is achieved using either 10 mol % 1,1,3,3-tetramethylguanidine (TMG) or 10 mol % phosphazene (t-Bu-P1) as organic base catalysts in good to high yields. On the other hand, N-sulfinylketimines also furnished the aza-Henry product in good yield with moderate diastereoselectivity (3:1). Thus, the methodology developed here is a good template for developing the first organocatalytic approach towards the aza-Henry reaction of ketimines.

Graphical abstractDownload full-size image