Enantio- and Diastereoselective Nitro-Mannich Reactions with in situ Generated N-Boc-imines Catalyzed by a Bifunctional Thiourea–Guanidine Catalyst

摘要

The asymmetric nitro-Mannich reactions of nitroalkanes and in situ generated N-Boc-imines were achieved with a new type of thiourea-guanidine bifunctional organocatalyst. The novel transformations exhibited good diastereoselectivities, and the adducts bearing adjacent chiral centers were generally obtained in moderate to high enantioselectivities (up to 94% ee). This reaction provides a concise and alternative route converting readily accessible and stable N-carbamate amido sulfones into optically active 1,2-diamino compounds.