Studies on the synthesis of heterocyclic compounds. Part 698. An alternative protoberberine synthesis; total synthesis of (±)-xylopinine, (±)-schefferine, (±)-nandinine, (±)-corydaline, and (±)-thalictricavine

Abstract

9,10-Disubstituted protoberberines were synthesised by photolysis of the corresponding bromo-enamides in high yields. The products were converted into (±)-xylopinine, (±)-schefferine, (±)-nandinine, (±)-corydaline, and (±)-thalictricavine. Xylopinine was also synthesised, together with the corresponding styrene derivative, from the corresponding enamide under benzyne reaction conditions.