Electrochemical Oxidation of Proline Derivatives: Total Syntheses of Bulgecinine and Bulgecin C

Article abstract of DOI:10.1021/jo00008a040

The influence of structure on the efficiency of the electrochemical C-5 oxidation of (2S,4S)-hydroxyproline carbamate esters is presented.Optimum methoxylation was observed with (2S,4S)-4-acetoxy-1,2-pyrrolidine-dicarboxylic acid 2-methyl 1-(2-(trimethylsilyl)ethyl) ester (19).The corresponding C-5 methoxy derivative 20 was converted into bulgecinine (4) via a stereospecific radical homologation to incorporate the C-5 hydroxymethyl substituent.Bulgecin C (1c) was prepared via a β-stereoselective glycosidation reaction using a 2-azido-2-deoxy-α-D-glucopyranosyl trichloroacetimidate derivative, regiospecific C-4' sulfation, and deprotection.