5-Amino-8-methyl-1,2-dihydrothieno(and furo)[2,3-h][1,6]naphthyridines

X-ray structure analyses of Smiles rearrangement and further cyclization products of 2-[3-cyanopropylthio(and oxy)]pyridine-3-carbonitriles revealed the structures of 5-amino-8-methyl-1,2-dihydrothieno[2,3-h][1,6]naphthyridine, C₁₁H₁₁N₃S, and 5-amino-8-methyl-1,2-dihydrofuro[2,3-h][1,6]naphthyridine, C₁₁H₁₁N₃O. The crystals of both compounds are isomorphous; monoclinic, space group P2₁/n. The molecules, related by a centre of symmetry, are linked through a N—H...N hydrogen bond. Common features of bond lengths and angles which characterize the thieno and furo[2,3-h][1,6]naphthyridine skeletons are described.

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