Synthesis of saframycins. V. Selenium oxide oxidation of hexahydro-1,5-imino-3-benzazocin-7,10-dione; a useful method for constructing saframycins C and D from saframycin B

(±)-Saframycins C (3)and D (4) have been synthesized for the first time by the regiospecific and stereoselective oxidation of (±)-saframycin B (2) with selenium oxide.