Synthetic studies of α-amino-β-hydroxy-γ-butyrolactone and stereoselective syntheses of tertiary alcohols

Abstract

For the synthesis of α-amino-β-hydroxy-γ-butyrolactone 1, the preparation of the key intermediate 16 was considered important. The key feature of the synthetic route to 16 includes azidolysis of trans-epoxide 35 and the regioselective epoxide opening of epoxy alcohol 44 with $NH_4OH$. To develop a stereoselective synthetic pathway to tertiary alcohols, a few experiments were planned. These include: the diastereomeric differentiation of $C_2$ symmetric triol 47 containing 3 or 5 stereogenic centers prepared by one pot-asymmetric allylation/crotylation of di-aldehyde 46 and stepwise asymmetric allylation/crotylation of mono-aldehyde and Lewis acid-catalyzed desymmetrization of meso-triols. Due to the inefficiency in preparing 47, the first approach could not be examined. The second approach has found respective using $C_2-symmetric$ chiral bisoxazolines.