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 hydra te. The hydrazones were used as key intermediates for the preparation of so me benzopyrano-[2,3-c]pyrazoles (21-24) through the reaction of different a cyl halides and subsequent cyclization in N,N-dimethylaniline. Benzopyrano[ 2, 3-c]pyrazole-3-thione (25a,b) was prepared by the reaction of la with CS , on which some alkylation, acylation and Mannich reactions were studied. A lternative procedures, other reactions and biological activity of some new compounds were given. (C) 1999 Elsevier Science S.A. All rights reserved.