Regioselective Baeyer–Villiger lactonization of 2-substituted pyrrolidin-4-one. Synthesis of statine

Nine 2-substituted pyrrolidin-4-ones 4a–i were obtained via a series of functional group transformation of known prolinol 5 by facile six kinds of methodologies. The target structure of 1,3-amino alcohols 2a–i was constructed in the regioselective Baeyer–Villiger lactonization of ketones 4a–i and reduction of the resulting 4-substituted tetrahydro-1,3-oxazin-6-ones 3a–i. A new and straightforward synthesis of (3S,4S)-statine (6) has been established starting from trans-(2S,4R)-4-hydroxyproline (1).