Asymmetric Organocatalytic Formal Aza-Michael Addition of Ammonia to Nitroalkenes

The formal addition of ammonia to nitroalkenes, affording optically active β‐amino nitro compounds in high yields and enantioselectivities, is presented (see scheme). The approach is based on a novel thiourea‐catalyzed aza‐Michael reaction, by which benzophenone imine serves as a masked ammonia equivalent, which is released by hydrolysis.