High Asymmetric Induction in Conjugate Additions of RCu*BF3 to Chiral Enoates

Article abstract of DOI:10.1002/hlca.19810640842

1,4-Additions of PhCu*BF3, n-BuCu*BF3 and MeCu*BF3 to the trans-8-phenylmenthyl enoates 1 proceeded with high chiral induction.Saponification of the resulting esters 2 gave the corresponding enantiomerically pure β-substituted alkanoic acids 3 and the recovered (-)-8-phenylmenthol in good overall yields.Analogous additions to the cis-crotonate 1 led preferentially to the acids 3 enantiomeric to those obtained from the trans-crotonate 1, although with lower selectivity.A stereochemical model is proposed consistent with the observed results (Scheme 2, Table).