Bifunctional catalysis in the stereocontrolled synthesis of tetrahydro-1,2-oxazines

Abstract

This study demonstrates that the annulation of a tetrahydro-1,2-oxazine ring can be realized via bifunctional catalysis, employing nitroolefins and a recently introduced group of aminooxylating reagents as starting materials. The developed cascade reactivity proceeds in a sequence aza-Michael–Michael reaction. The target products, bearing three contiguous stereocenters, have been obtained with high yields (up to 97%) and excellent stereocontrol (>20 : 1 dr, up to 99.5 : 0.5 er).