Synthesis of some new biologically-active coumarin derivatives

Coumarin and 6-nitrocoumarin hydrazones (2a,b), respectively, were prepared via the reaction of 2-thiocoumarin (1a,b) derivatives with hydrazine hydrate. The hydrazones were used as key intermediates for the preparation of some benzopyrano[2,3-c]pyrazoles (21-24) through the reaction of different acyl halides and subsequent cyclization in N,N-dimethylaniline. Benzopyrano[2,3-c]pyrazole-3-thione (25a,b) was prepared by the reaction of 1a with CS2 on which some alkylation, acylation and Mannich reactions were studied. Alternative procedures, other reactions and biological activity of some new compounds were given.