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 ...
