Performance of C1-symmetric chiral ammonium betaines as catalysts for the enantioselective Mannich-type reaction of α-nitrocarboxylates

The catalytic performance of C-1-symmetric chiral ammonium betaines in the enantioselective direct Mannich-type reaction of alpha-nitrocarboxylates with N-Boc imines has been investigated. The most effective catalyst structure has been identified; this provides a reliable synthetic route to a variety of enantiomerically enriched alpha-tetrasubstituted alpha,beta-diamino acid derivatives. (C) 2010 Elsevier Ltd. All rights reserved.