Enantioselective Synthesisof (-)-(<i>R</i>)-Baclofen and Analoguesvia Rhodium-Catalysed Conjugate Addition of Boronic Acids
作者:Günter Helmchen、Oliver Meyer、Jean-Michel Becht
DOI:10.1055/s-2003-40847
日期:——
Highly enantioselective syntheses of the antispastic drug (-)-(R)-Baclofen and analogues have been achieved by using rhodium-catalysed asymmetric 1,4-additions of arylboronic acids to 4-amino-but-2,3-enoic acid derivatives.
γ-amino butyric acid derivatives were synthesized in good enantioselectivities via the Cu-catalyzed asymmetric conjugate reduction of γ-phthalimido-α,β-unsaturated carboxylic acid esters using Cu(OAc)2·H2O as a catalyst precursor, (S)-BINAP as a ligand, PMHS as a hydride source, and t-BuOH as an additive. The methodology has been applied successfully to the enantioselective synthesis of a chiral pharmaceutical