Ring Contraction of 4-Diazo-1-phenyl-5,6-dioxo-1,4,5,6-tetrahydropyridazine in the Solid Stave via “Pyrazolo-lactone”

Abstract

Conversion of 4-diazo-1-phenyl-5,6-dioxo-1,4,5,6tetrahydropyridazine into "pyrazolo-lactone", from which different 5-hydroxy-1-phenyl-pyrazoles can be formed in the solid state, is described.Several examples of ring contraction of substituted pyridazinones into 2-6 pyrazole derivatives either under basic or acidic conditions have been reported .7on the other hand, since the Siiss-s first report , a number of heterocyclic carboxylic acids and their derivatives has been prepared from heterocyclic 9 a-diazo ketones8 either by thermal or photochemical Wolff rearrangement .i n this manner, 4-diazo-l-phenyl-5,6-di0~0-1,4,5,6-tetrahdr0pyridazine has been converted