syn-Selective Catalytic Asymmetric Nitro-Mannich Reactions

Significance

This communication highlights the first syn-selective catalytic asymmetric nitro-Mannich reaction. The catalyst consists of a hetero­bimetallic Cu-Sm-Schiff base complex synthesized from a dinucleating Schiff base ligand in two steps. The scope is broad with a variety of N-Boc imines affording high yields, syn selectivities, and enantioselectivities, including imines with electron-donating, electron-withdrawing, and hetero­aryl substituents. Even isomerizable alkyl N-Boc imines and use of nitropropane instead of nitro­ethane afford high yields and selectivities. The synthetic utility is demonstrated by converting one of the products into syn-1,2-diamines in two steps and with excellent yields.