Synthesis of phenanthroindolizidines. II. The synthesis of (±)-tylocrebrine, (±)-tylophorine, (±)-antofine, and (±)-2,3-dimethoxyphenanthroindolizidine

Abstract

A new synthesis of the racemic forms of the phenanthroindolizidine alkaloids, tylocrebine, tylophorine, and antofine, together with the previously unknown 2,3-dimethoxyphenanthroindolizidine, is described. Some features of the n.m.r. spectra of the final products and certain of the synthetic intermediates are discussed.