Naphthyridines. Part IV. Preparation of anthyridines and pyrimido-[4,5-b][1,8]naphthyridines from 2-amino-1,8-naphthyridines
Abstract
Syntheses of anthyridines by thermal cyclisation of 2-ethoxycarbonylvinylamino-1,8-naphthyridines, from derivatives of 2,6-diaminopyridine, and from 3-substituted 2-amino-1,8-naphthyridines, have been investigated. Pyrimido[4,5-b][1,8]naphthyridines have been prepared by cyclisation of 2-acetamido-1,8-naphthyridine-3-carboxamides.