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Paper | Special issue | Vol 54, No. 2, 2001, pp.667-678
Published online, 1st January, 1970
DOI: 10.3987/COM-00-S(I)41
Reaction of 2-Aminoazulenes with Aldehydes. One Pot Synthesis of Diazuleno[2,1-b:1,2-e]pyridines

Tetsuo Okujima, Tomomi Terazono, Shunji Ito,* Noboru Morita,* and Toyonobu Asao

*Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan

Abstract

Diazuleno[2,1-b:1,2-e]pyridines (2a and 2b) were prepared in one pot by the reaction of 2-aminoazulene (1a) with paraformaldehyde or benzaldehyde in moderate yields. Bis(2-amino-3-ethoxycarbonyl-1-azulenyl)methane (8a) was formed by the reaction of ethyl 2-aminoazulene-1-carboxylate (1b) with 1/2 molar amount of paraformaldehyde. Treatment of 8a with paraformaldehyde at room temperature afforded three heterocyclic compounds (9, 10, and 11). When 2-acetylaminoazulenes (1c and 1d) were used for this reaction, bis(2-acetylamino-1-azuleny)methanes (8b and 8c) were exclusively formed.