Cu-catalyzed asymmetric conjugate reduction of β-substituted α,β-unsaturated phosphonates: an efficient synthesis of optically active β-stereogenic alkylphosphonates

A series of chiral alkylphosphonates bearing beta-stereogenic center were synthesized in good enantioselectivities (up to 95% ee) via the CuH-catalyzed asymmetric conjugate reduction of beta-substituted alpha,beta-unsaturated phosphonates under optimal conditions using Cu(OAc)(2)center dot H2O as the copper source, (R)-SEGPHOS as the ligand. PMHS as the siloxane, and t-BuOH as the additive. (C) 2009 Elsevier Ltd. All rights reserved.