Asymmetric 1,4 addition of Grignard reagents to chiral α,β- unsaturated esters in the presence of Lewis acids

Article abstract of DOI:10.1016/S0040-4020(99)00267-7

The synthesis of enantiomerically enriched α-amino acids is described, by means of the diastereoselective conjugate addition of Grignard reagent to (S)-2-acetamidoacrylic ethoxycarbonylphenyl-methyl ester 1 and its N-Boc derivative 5 in the presence of Lewis acids. The addition of magnesium organocuprates has also been analysed. The reaction proceeds with good yields and variable diastereoselectivities, depending on the organometallic reagent and on the Lewis acid utilised.