The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized. (C) 2010 Elsevier Ltd. All rights reserved.
Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction / Monica, Orsini; Chiarotto, Isabella; Giovanni, Sotgiu; Inesi, Achille. - In: ELECTROCHIMICA ACTA. - ISSN 0013-4686. - 55:10(2010), pp. 3511-3517. [10.1016/j.electacta.2010.01.082]
Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction
CHIAROTTO, Isabella;INESI, ACHILLE
2010
Abstract
The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized. (C) 2010 Elsevier Ltd. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
