1,3-DIPOLAR CYCLOADDITION OF DIPHENYLNITRILIMINE AND 5-ARYLMETHYLIDENE-1-PHENYL-1,5,6,7-TETRAHYDRO-4<i>H</i>-INDAZOL-4-ONES TO AFFORD NOVEL SPIRO[INDAZOLE-5,3'-PYRAZOLE] DERIVATIVES

Abstract

Novel 4'-aryl-1,2',5'-triphenyl-2',4',6,7-tetrahydrospiro[indazole-5,3'-pyrazol]-4(1H)-ones have been synthesized in moderate yields by 1,3-dipolar cycloaddition of 5-arylmethylidene-1-phenyl-1,5,6,7-tetrahydro-4H-indazol-4-ones and diphenylnitrilimine, generated in situ from N-phenylbenzohydrazonoyl chloride and triethylamine. According to structural analyses by NMR spectroscopy and single crystal X-ray diffraction method, the reaction proceeds regioselectively affording products with C(5)–C(3') connectivity at the spiro center.