Highly convergent synthesis of a rebeccamycin analog with benzothioeno(2,3-a)pyrrolo(3,4-c)carbazole as the aglycone

A highly convergent, scalable synthesis of the rebeccamycin analog 2 was demonstrated in seven steps and 31% overall yield based on the N-protected building block dibromomaleimide 7. The practical synthesis of other two building blocks, 5,6-difluoro-3-benzothiopheneboronic acid 6 and 5,6-difluoroindole 8, is described.