SYNTHESIS OF NEW 2H,4H-BENZOPYRANO[3,4-B]PYRIDINE-1,3,5-TRIONE DERIVATIVES VIA CARBON SUBOXIDE

The new 2H,4H-[1]benzopyrano[3,4-b]pyridine-1,3,5-trione derivatives 1 0a-f were prepared in the following three steps: first the preparation of new tert-butoxycarbonyl)-3-amino-2H-1-benzopyran-2-one derivatives 5a-f by reaction of coumarin-3-carboxylic acids and diphenylphosphory lazide, then hydrolysis of 5a-f with gaseous hydrogen chloride to give the corresponding amines 7a-f, and finally the preparation of 10a-f b y reaction of 7a-f and carbon suboxide in the presence of a Lewis acid .