DEVELOPMENT OF A PRACTICAL SYNTHESIS OF 7-BROMO-8-METHOXYCARBONYL-3,3-DIMETHYL-3,4-DIHYDRO-1H- QUINOXALIN-2-ONE

摘要

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.