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The three-component reaction of N-phenacylbenzothiazolium bromides, aromatic aldehydes and indane-1,3-dione in ethanol at room temperature in the presence of triethylamine as base afforded functionalized spiro[benzo[ d]pyrrolo[2,1- b]thiazole-3,2′-indenes] in good yields and with high diastereoselectivity. The 1H NMR data and single crystal structure clearly indicated that the obtained spiro compounds predominately have one diastereoisomer. [ABSTRACT FROM AUTHOR]

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]