Fused heterocycles. Part 3. Synthesis and stereochemistry of benzopyrano and benzothiapyrano-[4,3-c]pyrazoles

Abstract

Several tricyclic benzopyrano[4,3-c]pyrazole derivatives have been studied by 1H and 13C n.m.r. spectroscopy. They were prepared by treating 3-benzylidene-chromanones and -1-thiochromanones with semicarbazide or thiosemicarbazide: reactions which give only the cis 3-H,3a-H stereoisomers.