Condensation of triformylmethane with heteroaromatic amines, including nucleic acid bases. A novel example of ring-chain tautomerism



: Neuvonen K, Zewi C, Lonnberg H

Publisher: MUNKSGAARD INT PUBL LTD

: 1996

: Acta Chemica Scandinavica

: ACTA CHEMICA SCANDINAVICA

: ACTA CHEM SCAND

: 50

: 12

: 1137

: 1142

: 6

: 0904-213X

DOI: https://doi.org/10.3891/acta.chem.scand.50-1137


Treatment of several heteroaromatic amines, including the nucleic acid bases cytosine and adenine, with triformylmethane in pyridine at 70 degrees C afforded 1:1 condensation products (2-11) that were characterized by H-1 and C-13 NMR spectroscopy. All the compounds were assigned as N-substituted aminomethylenemalonaldehydes, strongly preferring the amino/keto form over the imino/enol tautomer. With cytosine and 1-methylcytosine, unequivocal evidence for ring-chain tautomerism was additionally obtained: intramolecular nucleophilic attack of cytosine N3 to one of the carbonyl carbons results in reversible cyclization to a 4-hydroxy-4H-pyrimido[1,6-a]pyrimidin-6(7H)-one derivative (9b, 10b). In dry methanol the corresponding O-methyl ether (12) was obtained.



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