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In the presence of DIPEA (diisopropylethylamine), a formal [3+2] cycloaddition reaction between diazooxindoles and oxazol-5-(4H)-ones takes place easily to give new 3-(1H-1,2,4-triazol-1-yl)indolin-2-ones in 61-98% yield. The structure of the target molecules was confirmed by single-crystal X-ray structure analysis. [ABSTRACT FROM AUTHOR]

In the presence of Na2CO3, the [3+2] cycloaddition of azaoxyallyl cations, in situ formed from α-halohydroxamates by reaction with isothiocyanides, proceeded smoothly and furnished ( Z)-2-iminothiazolidin-4-ones in 25-99 % chemical yields. The chemical structure of the title compounds was confirmed by X-ray single-crystal structure analysis. [ABSTRACT FROM AUTHOR]

Catalyzed by 10 mol-% PhCO2H, the [3+2] cycloaddition between 3-isothiocyanato oxindoles and nitroso compounds proceeded readily to deliver 1,2,4-oxadiazolidine-3-thione-fused spirooxindoles in 40-82 % yield. The structures of the title compounds were firmly confirmed by X-ray single-crystal structure analysis. [ABSTRACT FROM AUTHOR]

Catalyzed by a Cinchona-based thiourea, the [3+2] cycloadditions of barbiturate-based olefins with 3-isothiocyanatooxindoles proceeded readily, and furnished dispirobarbiturates in excellent chemical yields with excellent diastereo- and enantioselectivities. The absolute configuration of dispirobarbiturates was firmly confirmed by an X-ray single crystal structure analysis. A reaction mechanism was proposed to account for the enantioselective formation of dispirobarbiturates. [ABSTRACT FROM AUTHOR]

In the presence of sodium carbonate, the [4+3] cycloadditions of α-halogeno hydrazones with nitrones were performed efficiently, and affording 2,3,4,7-tetrahydro-1,2,4,5-oxatriazepines in moderate to high yields. [ABSTRACT FROM AUTHOR]

In the presence of a Cinchona alkaloid-based squaramide organocatalyst, the [3+2] cycloaddition of isatin-derived azomethine ylides with maleimides proceeded readily, thus delivering the desired pyrrolidine-fused spirooxindoles in 61-89% yields with >20:1 dr and 12 to >99 % ee. The absolute configuration of 5-chloro-1,5′-dimethyl-3′-phenyl-3′,3a′-dihydro-2′ H-spiro[indoline-3,1′-pyrrolo[3,4- c]pyrrole]-2,4′,6′(5′ H,6a′ H)-trione was unambiguously determined by means of X-ray single crystal structure analysis. The reaction mechanism was hypothesized to account for the enantioselective formation of 5-chloro-1,5′-dimethyl-3′-phenyl-3′,3a′-dihydro-2′ H-spiro[indoline-3,1′-pyrrolo[3,4- c]pyrrole]-2,4′,6′(5′ H,6a′ H)-trione. [ABSTRACT FROM AUTHOR]

30 examples [ABSTRACT FROM AUTHOR]

An abstract of the article "Construction of 2,3,4,7-Tetrahydro-1,2,4,5-oxatriazepines via [4 + 3] Cycloadditions of α-Halogeno Hydrazones with Nitrones," by T. Tian et al. is presented.

An abstract of the study "Facile Construction of Novel Imidazolidine-Spirooxindoles via Diastereoselective Cycloaddition of N-Acylhydrazine-Derived Imines with 3-Isothiocyanato Oxindoles" is presented.

The article discusses spirocyclic compounds including dipolar cycloadditions of N,N'-Cyclic azomethine imines, Iminooxindoles and the synthesis of Oxindole Spiro-N,N-bicyclic Heterocycles.

A diagram is presented which shows the diastereoselective synthesis of dispirobarbiturates via cycloaddition of barbiturate-olefins with 3-isothiocyanato oxindoles.

In the presence of the Cinchona alkaloid-based squaramide organocatalyst QSQ, the [3+2] cycloaddition of isatin-derived azomethine ylides with maleimides proceeds readily to deliver pyrrolidine-fused spirooxindoles. [ABSTRACT FROM AUTHOR]