Synthesis of some 5,6,7,8-tetrahydro-4-cinnolone derivatives and 1-methyl-3-arylacetyl-4,5,6,7-tetrahydroindazoles

2-Arylidene-3-oxo-2,3,4,5,6,7-hexahydrobenzo[b]furans 2 react with hydrazine hydrate to afford 5,6,7,8-tetrahydro-4-cinnolones. By methylation, these compounds gave the corresponding N-1 and N-2 methyl derivatives. The mesoionic compounds are obtained, accompanied by 3-arylacetyl-4,5,6,7-tetrahydroindazoles upon reaction of 2 with methylhydrazine.