Wittig condensations of a thietan -2-one with stabilised phosphoranes

Abstract

(3R)-3-Benzyloxycarbonylamino-4,4-dimethylthietan-2-one reacts with ethoxycarbonylmethylenetriphenyl-phosphorane to give (3R)-3-benzyloxycarbonylamino-2-ethoxycarbonylmethylene-4,4,-dimethylthietan, as a mixture of (E)-and (Z)-diastereoisomers; corresponding Witting condensations occur with cyanomethylene-and acetonylidene-triphenylphosphorane.