Enantioselective Synthesis of (2S,3R)-3-Hydroxy-3-methylproline, A Novel Amino Acid Found in Polyoxypeptins

The enantioselective synthesis of (2S,3R)-3-hydroxy-3-methylproline (3) was achieved by the Sharpless AD, regioselective opening of cyclic sulfate by NaN(3) and intramolecular ring-closing reaction. The reported route has the advantage of a high overall yield and good enantiomeric purity, as well as starting from readily available chemical substrates and inexpensive reagents.