Starting from (E)-beta-substituted-beta-nitroacrylates and alpha,beta-unsaturated ketones, a stereoselective organo-catalyzed one-pot methodology allowed to synthesize highly decorated chiral 2-nitro-cyclohexane carboxylic esters. The reaction is promoted by Cinchona alkaloid-derived primary amines in the presence of an acidic co-catalyst and affords two diastereoisomers, in good yields and high enantiomeric excess (often higher than 90% ee). By replacing conventional heating with microwave irradiation, cleaner reactions in shortened times (from 48 h to 30 min) were obtained, with improved dr (80:20) and high ee (up to 94%). The application of microwave technology to this organocatalytic methodology allowed also employing Cl substituted enones, leading to cyclohexanones with four contiguous stereocenters in two isomers only, and up to 99% enantioselectivity.

Synthesis of highly decorated chiral 2-nitro-cyclohexane carboxylic esters through microwave-assisted organocatalyzed cascade reactions / E. Massolo, M. Benaglia, D. Parravicini, D. Brenna, R. Annunziata. - In: TETRAHEDRON LETTERS. - ISSN 0040-4039. - 55:49(2014), pp. 6639-6642.

Synthesis of highly decorated chiral 2-nitro-cyclohexane carboxylic esters through microwave-assisted organocatalyzed cascade reactions

E. Massolo;M. Benaglia;D. Brenna;R. Annunziata
2014

Abstract

Starting from (E)-beta-substituted-beta-nitroacrylates and alpha,beta-unsaturated ketones, a stereoselective organo-catalyzed one-pot methodology allowed to synthesize highly decorated chiral 2-nitro-cyclohexane carboxylic esters. The reaction is promoted by Cinchona alkaloid-derived primary amines in the presence of an acidic co-catalyst and affords two diastereoisomers, in good yields and high enantiomeric excess (often higher than 90% ee). By replacing conventional heating with microwave irradiation, cleaner reactions in shortened times (from 48 h to 30 min) were obtained, with improved dr (80:20) and high ee (up to 94%). The application of microwave technology to this organocatalytic methodology allowed also employing Cl substituted enones, leading to cyclohexanones with four contiguous stereocenters in two isomers only, and up to 99% enantioselectivity.
Cyclohexane carboxylic esters; Organocatalysis; Stereoselective reactions; Cinchona alkaloids; Cascade reactions
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/2434/463344
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