Synthesis of 4,5-Disubstituted Benzo[c][2,7]naphthyridines by Combined Metalation-Palladium-Catalysed Cross-Coupling Strategies. Preparation of 8h-Pyrido[4,3,2-mn]acridone as a Model of Cystodytin Alkaloids

Abstract

A short and efficient synthesis of 8H-pyrido[4,3,2-mn]acridone is described. The strategy involves the preparation of 4-chloro-5-methylbenzo[c][2,7]naphtyridine, as key intermediate, by metalation and Palladium catalyzed cross-coupling reaction. A second cross-coupling reaction and subsequent oxydation by SeO₂ led to the title compound.