Asymmetric conjugate addition of organometallic reagents to chiral α, β-unsaturated esters

Abstract

Asymmetric conjugate addition to α,β-unsaturated ester was studied using four kinds of cyclic diols ( 1c–4c) as chiral auxiliaries. Among the tested substrates, ( R,R)-cyclohexane-1,2-diol derivatives ( 6a–c) and (1 R,2 S)-2-hydroxymethylcyclopentanol derivative ( 7a) showed high and reverse diastereoselectivity in conjugate addition by organocuprates (R 2CuLi) and/or Grignard reagents in the presence of copper iodide (RMgBr + CuI), respectively.