4-Azido-3-coumarincarbaldehydes 2a-d are useful starting superior to the corresponding 4- chloro-3-coumarincarbalde-materials for syntheses of a variety of 3, 4-disubstituted cou- hydes la-d, from which they were prepared. An improved marins as well as heterocyclic [c]- fused coumarins, eg isox-method for the preparation of la-d from 4-hydroxyazoles, pyrazoles and 1, 5-diazepines, under mild conditions. In coumarins is described. these reactions, 2 ...