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Paper | Regular issue | Vol 41, No. 5, 1995, pp.1013-1022
Published online, 1st January, 1970
DOI: 10.3987/COM-95-7037
Cyclization of 2-Dicyanomethylene-1,2-dihydropyridine-3-carbonitriles with Hydrogen Halides: A Re-examination on the Regioselectivity

Pedro Victory, Núria Busquets, José I. Borrell,* Jordi Teixidó, Blanca Serra, Josep Lluís Matallana, Hans Junek, and Heinz Sterk

*Departament de Química Orgànica, CETS Institut Químic de Sarrià, Universitat Ramon Llull, E-08017 Barcelona, Spain

Abstract

The cyclization of the title compounds (5a-c) with HCl and HBr has been re-examined. In all cases 5-amino-7-halo-substituted 1,6-naphthyridines (11a-c and 12a-c) were formed independently of the thermal level and the hydrogen halide employed. The structures of 11a-c and 12a-c were unequivocally established by reaction with hydrazine which afforded the corresponding pyrazolo[3,4-h][1,6]naphthyridines (14a-c). The structure of the methoxy derivatives (15a,c and 16a,c) was assigned by two-dimensional nmr studies.