TRYPTAMINES, CARBOLINES, AND RELATED COMPOUNDS: PART X. AN ALTERNATIVE SYNTHESIS, AND THE NITRATION, OF δ-CARBOLINE

Abstract
δ-Carboline, together with β-carboline, has been synthesized in reasonably good yield by the Fischer cyclization of cyclohexanone 3-pyridylhydrazone followed by dehydrogenation of the separated tetrahydro derivatives. The isomer ratios of products formed in this and similar reactions are discussed. Nitration of δ-carboline gives a mixture of the 6- and 8-nitro derivatives, the latter being the predominant product. The magnitude of the dipole moment of δ-carboline is appreciably higher than that predicted from molecular orbital calculations (15).