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Paper | Regular issue | Vol 91, No. 8, 2015, pp.1591-1602
Published online, 9th July, 2015
DOI: 10.3987/COM-15-13240
■ Development of a Practical Synthesis of 7-Bromo-8-methoxycarbonyl-3,3-dimethyl-3,4-dihydro-1H-quinoxalin-2-one

Kazuhiro Kudo,* Takahiro Honda, and Noriyoshi Yamamoto

*Product Supply Division, Santen Pharmaceutical Co., Ltd., 348-3, Aza Suwa Oaza Shide Taga-cho Inugami-gun Shiga, Japan

Abstract

Synthesis of 7-bromo-8-methoxycarbonyl-3,3-dimethyl-3,4-dihydro-1H-quinoxalin-2-one from 5-amino-2-bromobenzoic acid was achieved in an overall yield of 27% over four steps. This is a significant improvement from the previous six-step process, which afforded only a 12% yield. The previous process was optimized by adding a high-yielding alkylation step under mild conditions as well as by reducing the number of isolation steps and eliminating purification by column chromatography.