A number of 1-aryl-5-substituted-4,5-dihydropyrazoles 4 have been synthesised by 1,3-dipolar cycloaddition of variously substituted nitrilimines 2 onto the appropriate alkenyl dipolarophiles 3 in aqueous media and in the presence of a surfactant. Under these conditions, uncommon for the large majority of [3 + 2] cycloadditions, the electronic features of both the cycloaddends strongly dictate the reaction outcome. Clean and fast cycloadditions were observed between electron-rich nitrilimines and electron-poor dipolarophiles, while the reversal of the electronic features of the reactants gave poor results. Changes in surfactant concentration leads to some novel mechanistic insights.

Uncommon aqueous media for nitrilimine cycloadditions. I. Synthetic and mechanistic aspects in the formation of 1-aryl-5-substituted-4,5-dihydropyrazoles / G. Molteni, A. Ponti, M. Orlandi. - In: NEW JOURNAL OF CHEMISTRY. - ISSN 1144-0546. - 26:10(2002), pp. 1340-1345.

Uncommon aqueous media for nitrilimine cycloadditions. I. Synthetic and mechanistic aspects in the formation of 1-aryl-5-substituted-4,5-dihydropyrazoles

G. Molteni;
2002

Abstract

A number of 1-aryl-5-substituted-4,5-dihydropyrazoles 4 have been synthesised by 1,3-dipolar cycloaddition of variously substituted nitrilimines 2 onto the appropriate alkenyl dipolarophiles 3 in aqueous media and in the presence of a surfactant. Under these conditions, uncommon for the large majority of [3 + 2] cycloadditions, the electronic features of both the cycloaddends strongly dictate the reaction outcome. Clean and fast cycloadditions were observed between electron-rich nitrilimines and electron-poor dipolarophiles, while the reversal of the electronic features of the reactants gave poor results. Changes in surfactant concentration leads to some novel mechanistic insights.
Settore CHIM/06 - Chimica Organica
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/187765
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