Stereoselective synthesis of thienyl and furyl analogues of ephedrine

Article abstract of DOI:10.1016/S0957-4166(96)00528-9

The stereoselective syntheses of thienyl and furyl analogues of ephedrine starting from (R)- and (S)-cyanohydrins, respectively, are described. Addition of methyl Grignard to the O-trimethylsilyl protected optically active cyanohydrins (R)- and (S)-3 and hydrogenation of the resulting imino intermediates gives the erythro-2-amino alcohols 4 with high diastereoselectivity. Their reductive methylation leads to the enantiomerically pure thiophene analogues (1S,2S)- and (1R,2R)-6a, (1R,2S)- and (1S,2R)-6b as well as to the furan analogues (1S,2S)-6c and (1R,2S)-6d of ephedrine, The biological activity of the new compounds is under investigation.