Synthesis of 2H-Indazole-4,7-dione Derivatives from 3-Phenylsydnone and p-Toluquinone. The Crystal and Molecular Structure of 6-Bromo-5-methyl-2-phenyl-2H-indazole-4,7-dione
The 1,3-dipolar cycloaddition of 3-phenylsydnone with p-toluquinone afforded 5-methyl-and 6-methyl-2-phenyl-2H-indazole-4,7-diones 3a and 3b.No regioselectivity was observed in this cycloaddition yielding an equimolar amount of the regioisomers.Reactions