Synthesis of novel spiro(indolizine-pyrazole) derivatives via 1,3-dipolar cycloaddition of nitrilimine.

The 1,3-dipolar cycloaddition of nitrilimine, generated in situ from N'-phenylbenzohydrazonoyl chloride and triethylamine, to 7-arylmethylidene-6,7-dihydroindolizin-8(5H)-one afforded novel 4'-aryl-2',5'-diphenyl-2',4',5,6-tetrahydro-8H-spiro(indolazine-7,3'- pyrazol)-8-ones in moderate yields. The structures of all the products were characterised thoroughly by NMR, infrared spectroscopy and HRMS. The structure and stereochemistry was confirmed by x-ray diffraction analysis [ABSTRACT FROM AUTHOR]