Unusual Regioselection in the Mitsunobu Reactions of s yn-2,3-Dihydroxy Esters:  Synthesis of Statine and Its Diastereomer

Mitsunobu reactions of syn-2,3-dihydroxy esters exhibit a complete regioselection for the β-hydroxyl group. Benzoylation, azidation, and tosylation have been performed under these conditions. β-Functionalizations of syn-2,3-dihydroxy esters are uncommon, and the Mitsunobu reactions are complementary to other diol chemistries in the regioselection. In addition, the configurational inversion accompanying the Mitsunobu protocol offers a means for diastereochemical diversity, as exemplified by a synthesis of statine and its anti diastereomer. These findings will further expand the synthetic utilities of the Sharpless AD process.