Naphthyridine chemistry. VIII. The mass spectra of the 1,X‐naphthyridines and some of their methyl derivatives

Abstract
The mass spectra of the four parent 1,X‐naphthyridines, the 2,3 and 4‐monomethyl‐1,5‐,1,6‐. and 1,8‐ naphthyridincs, seven dimethyl‐1,8‐naphthyridines, and one trimethyl‐1,8‐naphthyridine are reported. Evidence for an azatropylium ion intermediate in the fragmentation of the methyl compounds is presented. The fragmentation modes of the naphthyridines are similar to those for the quinolines in addition to several new processes