Condensation of β‐Diester Titanium Enolates with Carbonyl Substrates: A Combined DFT and Experimental Investigation |
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| Authors: | Alessandro Marrone Dr Andrea Renzetti Dr Paolo De Maria Prof Stéphane Gérard Dr Janos Sapi Prof Antonella Fontana Prof Nazzareno Re Prof |
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| Institution: | 1. Dipartimento di Scienze del Farmaco, Università degli Studi “G. d'Annunzio” di Chieti‐Pescara, Via dei Vestini, 66100 Chieti (Italy), Fax: (+39)?0871‐3554614;2. Faculté de Pharmacie, ICMR, UMR CNRS 6229, Université de Reims Champagne‐Ardenne, 51 rue Cognacq‐Jay, 51096 Reims Cedex (France) |
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| Abstract: | The condensation of dialkyl β‐diesters with various aldehydes promoted by TiCl4 has been studied by DFT approaches and experimental methods, including NMR, IR and UV/Vis spectroscopy. Various possible reaction pathways have been investigated and their energy profiles evaluated to find out a plausible mechanism of the reaction. Theoretical results and experimental evidence point to a three‐step mechanism: 1) Ti‐induced formation of the enolate ion; 2) aldol reaction between the enolate ion and the aldehyde, both coordinated to titanium; and 3) intramolecular elimination that leads to a titanyl complex. The presented mechanistic hypothesis allows one to better understand the pivotal role of titanium(IV) in the reaction. |
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| Keywords: | aldol reaction density functional calculations elimination Knoevenagel condensation titanium |
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