Synthesis of new 2H,4H-benzopyrano[3,4-b]pyridine-1,3,5-trione derivatives via carbon suboxide

Article abstract of DOI:10.1002/jhet.5570350122

The new 2H,4H-[1]benzopyrano[3,4-b]pyridine-1,3,5-trione derivatives 10a-f were prepared in the following three steps; the first preparation of new N-(tert-butoxycarbonyl)-3-amino-2H-1-benzopyran-2-one derivatives 5a-f by reaction of coumarin-3-carboxylic acids and diphenylphosphorlyazide, then hydrolysis of 5a-f with gaseous hydrogen chloride to give the corresponding amines 7a-f, and finally the preparation of 10a-f by reaction of 7a-f and carbon suboxide in the presence of a Lewis acid.