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Bifunctional cinchona alkaloid/thiourea catalyzes direct and enantioselective vinylogous Michael addition of 3-alkylidene oxindoles to nitroolefins

Curti, Claudio and Rassu, Gloria Maria Rita and Zambrano, Vincenzo and Pinna, Luigi and Pelosi, Giorgio and Sartori, Andrea and Battistini, Lucia and Zanardi, Franca and Casiraghi, Giovanni (2012) Bifunctional cinchona alkaloid/thiourea catalyzes direct and enantioselective vinylogous Michael addition of 3-alkylidene oxindoles to nitroolefins. Angewandte Chemie, Vol. 124 (25), p. 6304-6308. eISSN 1521-3757. Article.

Full text not available from this repository.

DOI: 10.1002/ange.201202027

Abstract

3-Alkylidene oxindoles (methyleneindolinones), be they natural or man-made substances, occupy a preeminent position among the various classes of chemically and medicinally relevant small-molecule scaffolds. Their plural functional architecture featuring a lactam carbonyl flanked by a highly substituted exocyclic double bond renders them enabling intermediates to be elaborated into a myriad of useful nitrogen heterocycles of varied complexity. For example, 3-alkylidene oxindoles can be viewed as electrophilic Michael acceptors, which react with carbon-centered anions to give bsubstituted oxindoles of type A (Scheme 1a). In addition, they can act as electron-poor components in synchronous (Scheme 1b) or stepwise (Scheme 1c) cycloadditive functionalizations, thus opening the way to a wide range of highly valuable 3,3-spirocyclic structures of type B or C. Whereas these protocols have been largely pursued and formed the basis of many synthetic achievements, an “umpolung” option could also be envisaged (Scheme 1d), and capitalizes on the vinylogous pro-nucleophilic character of the alkyl group attached at the b-position of the ylidene. By reacting with the proper acceptors, these nucleophiles furnish olefinic oxindoles of type D, which are functionalized at the most distant point of the molecule (Cγ).

Item Type:Article
ID Code:7552
Status:Published
Refereed:Yes
Uncontrolled Keywords:Asymmetric synthesis, heterocycles, Michael reaction, organocatalysis, umpolung
Subjects:Area 03 - Scienze chimiche > CHIM/06 Chimica organica
Divisions:001 Università di Sassari > 01-a Nuovi Dipartimenti dal 2012 > Chimica e Farmacia
002 Altri enti e centri di ricerca del Nord Sardegna > CNR-Consiglio Nazionale delle Ricerche > Istituto di chimica biomolecolare, Sassari
Publisher:Wiley
eISSN:1521-3757
Deposited On:10 May 2012 16:38

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