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Synlett 1995; 1995(6): 622-624
DOI: 10.1055/s-1995-5024
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Thermal Isomerization of 4-Amino-3-vinylpyridines: Synthesis of Fused 1,6-Naphthyridines and Unexpected New ”tert-Amino Effect” Cyclization to Azepines

V. Ojea, I. Muinelo, M. C. Figueroa, M. Ruiz, J. M. Quintela*
  • *Departamento de Química Fundamental e Industrial, Universidade da Coruña, Campus de Zapateira, La Coruña E-15071, Spain, Fax 34 81 105641; Bitnet jqqoqf@udc.es
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Publication History

Publication Date:
31 December 2000 (online)

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4-amino-3-(2,2-dicyanovinyl)pyridines react thermally in dimethylsulfoxide via [1,5] hydrogen transfer followed by carbon-carbon bond formation to give hexahydro-1H-amino[1,2-a][1,6]naphthyridine derivatives. The 4-piperazino, 4-morpholino- and 4-thiomorpholino-3-(2,2-dicyanovinyl)pyridines also lend themselves to the simultaneous formation of hexahydro-1H-imidazolo[2,1-f]pyrido[4,3-b]azepine, hexahydro-1H-oxazolo[2,3-g]pyrido[4,3-b]azepine and hexahydro-1H-pyrido[3,4-f]thiazolo[3,2-a]azepine derivatives, respectively, by a new ”tert-amino effect” type of cyclization. A rational explanation for the new reactivity based on a neighboring-group mechanism is put forward.

”tert-amino effect” - [1,6]-naphthyridine - azepine