A highly efficient asymmetric synthesis of optically active α,β-epoxyaldehydes from α,β-unsaturated acids

The bromolactones(3) prepared from α,β-unsaturated acids(1) were converted to optically active α,β-epoxyaldehydes(2(R),3(S)-6)(84–98% ee) by successive epoxide formation and reductive cleavage of the proline moiety. The overall process constitutes a highly efficient asymmetric synthesis of 2(R),3(S)-6 from 1.