Pinacol Cross Coupling Reactions of Ethyl 2-Alkyl-2-Formylpropionates. Stereoselective Synthesis of 2,2,4-Trialkyl-3-Hydroxy-γ-Butyrolactones

Article abstract of DOI:10.1055/s-1997-709

Intermolecular pinacol coupling of ethyl 2-alkyl-2-formylpropionates (2) (i.e. EtOC(O)CR¹MeCHO) with non-chelating aldehydes provides high yields of threo diols. The reaction is promoted by vanadium(II) ions which are conveniently generated in situ from VCl₃(THF)₃ and zinc dust. High diastereofacial selectivity is observed when starting with chiral 2, or chiral non-chelating aldehydes.