SYNTHESIS AND UNAMBIGUOUS ASSIGNMENT OF STRUCTURE TO PYRANOPYRAZOL-4(1H)-ONES AND -4(2H)-ONES

Article abstract of DOI:10.1246/cl.1986.295

A clean synthesis of pyranopyrazolones is described.The reactions of 4-chloro-3-(1-chlorovinyl)-6-methyl-2-pyrone with arylhydrazines give pyrano<4,3-c>pyrazol-4(2H)-ones as the only identified products.However, the isomeric pyrano<4,3-c>pyrazol-4(1H)-one