The stereospecific olefin formation reaction of 10-P-5 β-hydroxy- α,β-diphenylethylphosphoranes

Article abstract of DOI:10.1016/S0040-4039(97)10069-7

Deprotonation of P-H spirophosphorane 4 bearing Martin ligands with n- BuLi followed by reaction with trans-stilbene oxide gave a pair of anti-β- hydroxy-α,β-diphenylethylspirophosphoranes 5-Sp*R*S* and 5-Sp*S*R*, whereas treatment with cis-stilbene oxide yielded syn-β-hydroxy-α,β- diphenylethylspirophosphoranes 5-Sp*S*S*. The remaining diastereomer 5- Sp*R*R* was obtained selectively by α-benzoylation of benzyl- spirophosphorane 3 followed by reduction with LiBH₄. Deprotonation of the diastereomers with t-BuOK or t-BuONa lead to the stereospecific formation of stilbenes. The anti diastereomers gave cis-stilbene (Z:E=99:1) and the syn diastereomers furnished trans-stilbene (Z:E=1:99).