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Paper | Regular issue | Vol 36, No. 11, 1993, pp.2497-2508
Published online, 1st January, 1970
DOI: 10.3987/COM-93-6469
■ TiCl4 Promoted Ring Expansion Reactions of 5-Hydroxymethyl-2-isoxazoline-2-oxide Methanesulfonates

Kazuho Harada,* Yuko Shimozono, Eisuke Kaji, and Shonosuke Zen

*School of Pharmaceutical Sciences, Kitasato University, Shirokane, Minato-ku, Tokyo 108-8641, Japan

Abstract

5-Hydroxymetyl-2-isoxazoline-2-oxide methanesulfonates (1) possessing a substituted phenyl ring were treated with TiCl4 to afford either benzofuro[3,2-d]-1,2-oxazines (3) or 4-o-chlorophenyl-4H-1,2-oxazines (4), depending on the nature of the substituents on the phenyl ring of 1. The reaction mechanism of the formation of 3 and 4 is proposed, including 3H-indole-1-oxide zwitterion (B) as a key intermediate.