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1,3-Dipolar cycloadditions of a number of C-aryl, C-carbamoyl-, and C,C-bis(methoxycarbonyl)nitrones and substituted Nvinylpyrroles proceed with high efficiency and regioselectivity with the formation of only one isomeric substituted 5-(1H-pyrrol-1- yl)isoxazolidine cycloadduct. [ABSTRACT FROM AUTHOR]

Abstract The addition of Lewis acids changes the path of the reaction of N -vinylpyrroles with 3,4-dihydroisoquinoline- N -oxides: formal (3 + 3)-cycloaddition proceeds instead of (3 + 2)-cycloaddition. In the case of benzoyl(3,4-dihydroisoquinolin-2-ium-2-yl)amides, reaction path does not change in the same conditions, but changing of the diastereoselectivity occurs and other diastereomer of (3 + 2)-cycloaddition became predominant. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (C H⋯O) and moderate (N H⋯N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities. [ABSTRACT FROM AUTHOR]

The 1,3-dipolar cycloaddition of nitrones to N -propadienyl indoles and pyrroles proceeds predominantly via the C1-C2 bond to form 4-methyleneisoxazolidines. In the case of aldonitrones, the cis -isomers are predominantly formed. [ABSTRACT FROM AUTHOR]

The addition of Lewis acids change the reaction mechanism of the cycloaddition of N -vinylpyrroles with azomethine imine and C,N -diarylnitrones. The formal (3+3)-cycloaddition is observed instead of (3+2)-dipolar cycloaddition, which take place in the absence of catalysts. This unusual (3+3)-cycloaddition leads to heterocyclic compounds with pyrazolo[1,2- a ]pyrrolo[1,2- d ][1,2,4]triazine- and pyrrolo[2,1- d ][1,2,5]oxadiazine cores, which are difficultly achievable by other methods. [ABSTRACT FROM AUTHOR]