Effect of additives on the proline-catalyzed ketone–aldehyde aldol reactions

The effect of bases, acids, and water as additives in proline-catalyzed ketone–aldehyde aldol reactions has been studied. While the reaction appears to be relatively tolerant to small amounts of tertiary amine bases or weak acids, it stops completely with strong acids. The use of water as an additiv...

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Bibliographic Details
Published in:	Tetrahedron Vol. 62; no. 2; pp. 317 - 328
Main Authors:	Pihko, Petri M., Laurikainen, Katri M., Usano, Annina, Nyberg, Annika I., Kaavi, Jatta A.
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 01-01-2006
Subjects:	Aldehydes Aldol reactions Bases Ketones Organocatalysis Proline Water Water Ketones Aldol reactions Proline Aldehydes Bases Organocatalysis
Online Access:	Get full text
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Summary:	The effect of bases, acids, and water as additives in proline-catalyzed ketone–aldehyde aldol reactions has been studied. While the reaction appears to be relatively tolerant to small amounts of tertiary amine bases or weak acids, it stops completely with strong acids. The use of water as an additive had a highly beneficial effect on reactions that were conducted with a stoichiometric ratio of ketone to aldehyde, especially with cyclic ketones. This allows the efficient use of more precious ketones such as 4-thianone as donors in the direct enantioselective aldol and facilitates purification. Graphical Abstract
ISSN:	0040-4020 1464-5416
DOI:	10.1016/j.tet.2005.09.070