A Convenient Preparation of 7-Bromo-2H-1,4-benzothiazine-3,5,8(4H)-trione and Its Application in the Synthesis of the Conaquinone B Skeleton

摘要

7-Bromo-2H-1,4-benzothiazine-3,5,8(4H)-trione was synthesized by reaction of 5-bromo-2-nitro-1,4-benzoquinone with methyl thioglycolate followed by reductive cyclization and oxidation. The Diels-Alder reaction of the product quinone with myrcene afforded the expected naphthothiazine.