A Highly Efficient Solvent-Free Asymmetric Direct Aldol Reaction Organocatalyzed by Recoverable (s)-Binam-L-Prolinamides. ESI-MS Evidence of the Enamine-Iminium Formation
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Título: | A Highly Efficient Solvent-Free Asymmetric Direct Aldol Reaction Organocatalyzed by Recoverable (s)-Binam-L-Prolinamides. ESI-MS Evidence of the Enamine-Iminium Formation |
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Autor/es: | Guillena, Gabriela | Hita López, María del Carmen | Nájera, Carmen | Viózquez Cámara, Santiago Fidel |
Grupo/s de investigación o GITE: | Catálisis Estereoselectiva en Síntesis Orgánica (CESO) | Síntesis Asimétrica (SINTAS) |
Centro, Departamento o Servicio: | Universidad de Alicante. Departamento de Química Orgánica |
Palabras clave: | Solvent- free | Organocatalysis |
Área/s de conocimiento: | Química Orgánica |
Fecha de publicación: | 7-abr-2008 |
Editor: | American Chemical Society |
Cita bibliográfica: | Journal of Organic Chemistry. 2008, 73(15): 5933-5943. doi:10.1021/jo800773q |
Resumen: | Recoverable (Sa)-binam-l-prolinamide in combination with benzoic acid is used as catalysts in the direct aldol reaction between cycloalkyl, alkyl, and α-functionalized ketones and aldehydes under solvent-free reaction conditions. Three different methods are assayed: simple conventional magnetic stirring, magnetic stirring after previous dissolution in THF and evaporation, and ball mill technique. These procedures allow one to reduce not only the amount of required ketone to 2 equiv but also the reaction time to give the aldol products with regio-, diastereo-, and enantioselectivities comparable to those in organic or aqueous solvents. Generally anti-isomers are mainly obtained with enantioselectivities up to 97%. The reaction can be carried out under these conditions also using aldehydes as nucleophiles, yielding after in situ reduction of the aldol products the corresponding chiral 1,3-diols with moderate to high enantioselectivities mainly as anti-isomers. The aldol reaction has been studied by the use of positive ESI-MS technique, providing the evidence of the formation of the corresponding enamine−iminium intermediates. |
Patrocinador/es: | This work was financially supported by the Dirección General de Investigación of the Ministerio de Educación y Ciencia of Spain (Grant CTQ2004-00808/BQU, CTQ2007-62771/BQU and Consolider Ingenio 2010 CSD2007-00006), the Generalitat Valenciana (Grants CTIOIB/2002/320, GRUPOS03/134, and GV05/157), and the University of Alicante (GRJ06-05). |
URI: | http://hdl.handle.net/10045/34645 |
ISSN: | 0022-3263 (Print) | 1520-6904 (Online) |
DOI: | 10.1021/jo800773q |
Idioma: | eng |
Tipo: | info:eu-repo/semantics/article |
Derechos: | Copyright © 2008 American Chemical Society |
Revisión científica: | si |
Versión del editor: | http://dx.doi.org/10.1021/jo800773q |
Aparece en las colecciones: | INV - CESO - Artículos de Revistas INV - SINTAS - Artículos de Revistas |
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