A New Approach to (2S, 3S, 4S)-3-Hydroxy-4-Methylproline, A Subunit in Echinocandin B and Related Oligopeptide Antibiotics

A new approach to two protected forms of (2S, 3S, 4S)-3-hydroxy-4-methylproline, a constituent of echinocandins and related oligopeptide antibiotics is reported. The method features a highly regioselective and diastereoselective reductive furylation of protected (2S, 3S)-3-methylmalimide and a chemoselective oxidative transformation of furyl to carboxyl as the key steps.