Enantioselective nitroaldol reaction catalyzed by chiral C ₁-tetrahydro-1,1′-bisisoquinoline-copper(I) complexes

An efficient catalytic system comprising of chiral C₁- tetrahydro-1,1′-bisisoquinoline and CuCl in the ratio of 2:1 has been developed for the enantioselective Henry reaction. The catalytic efficiencies of the chiral C₁-tetrahydro-1,1′-bisisoquinolines are governed to a great extent by the structural constraints and the type of substituent on the sp³-N. Aromatic and aliphatic aldehydes reacted with nitromethane to give β-nitroalcohols in very high yields (up to 95%) and enantioselectivities (up to 91% ee). The present catalyst system is simple in operation since no special precautions were taken to exclude moisture or air from the reaction flask and no additives were required for activation. Nonlinear effects have also been studied for this reaction.