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Note | Regular issue | Vol 65, No. 11, 2005, pp.2799-2807
Published online, 13th September, 2005
DOI: 10.3987/COM-05-10537
New Approach to the Synthesis of Non-benzenoid Aromatic Compounds, Functionalized 1-Azaazulene Derivatives: Cyclization Reactions of 2-Substituted Tropones with N-Silylenamine and Enamine

Norio Sakai, Naoto Hattori, Nanako Tomizawa, Noritaka Abe, and Takeo Konakahara*

*Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, Noda, Chiba 278-8510, Japan

Abstract

The reaction of enamines with 2-subsituted tropones produced functionalized 1-azaazulene derivatives. When the reaction is conducted in an aprotic solvent, such as DMSO, the desired 1-azaazulene was obtained in 51% yield. The introduction of an electron-donating group on the enamine increased its nucleophilicity and improved the product yield. On the other hand, the reaction of enamines with 4-isopropyltropone-2-tosylate afforded a different 1-azaazulene derivative.