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The base mediated cycloaddition reactions of 4-dimethylamino-1-phenacylpyridinium bromides with two molecular 3-phenacylideneoxindoles in methylene dichloride afforded functionalized dispirocyclopentyl-3,3′-bisoxindoles in good yields and with high diastereoselectivity. The similar cycloaddition reactions of 1-( N, N-dialkylcarbamoylmethyl) and 1-cyanomethyl 4-dimethylamino-pyridinium bromide in refluxing ethanol in the presence of triethylamine also resulted in dispirocyclopentyl-3,3′-bisoxindoles with high diastereoselectivity. The stereochemistry of dispirocyclopentyl-3,3′-bisoxindoles was elucidated on the basis of 1H NMR data and single crystal structures. [ABSTRACT FROM AUTHOR]

The novel spirooxindoline fused [1,3]oxazines were efficiently synthesized from Diels-Alder reaction of N-arylmaleimides with 1,2-dihydro-2-oxospiro[3 H-indole-3,2′-[2 H,9a H-pyrido[2,1- b][1,3]oxazines], which were generated in situ from three-component reactions of substituted pyridines and isatins with methyl propiolate, or dimethyl acetylenedicarboxylate. The stereochemistry of the products was clearly clarified by the analysis of 1H NMR data and single crystal structures of the obtained polycyclic compounds. [ABSTRACT FROM AUTHOR]