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Paper | Special issue | Vol 88, No. 2, 2014, pp.997-1012
Published online, 22nd August, 2013
DOI: 10.3987/COM-13-S(S)55
■ Synthesis of 2-Substituted 1,3-Cycloheptanedione via a Lewis Acid Mediated Ring Expansion Reaction

Kohei Inomata* and Yasuyuki Endo*

*Faculty of Pharmaceutical Sciences, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

We have established a new route to provide 2-substituted 1,3-cycloheptanediones via a Lewis acid mediated ring expansion reaction of cyclobutanones as the key step. The ring expansion reactions were mediated by a series of Lewis acids. Among the used Lewis acids, ZnI2 was the most practical mediator. This route has succeeded in providing the title compounds even on a multi-gram scale. During the research, the Baeyer-Villiger oxidation of the cyclobutanones to obtain the new bicyclic lactones was also examined. The regioselective oxidation was observed in the case of chlorinated cyclobutanones.