Prolinamides as Organocatalysts in Aldol Reactions

The use of two different ketones in aldol reactions has been also studied although, as a general trend, an activated acceptor such as a-ketoesters, 

Sustainable Catalysis Without Metals or Other Endangered Elements, Part 1 

These include prolinamides derived from anilines 2a-c,h, 2-hydroxyanilines 2d-f, o-diaminobenzene derivatives 2g, amino-naphthalene ferrocenylamines 11, anthranilic acid-based pro- 

Catalyst 10 was introduced for reactions in aqueous systems in the presence of surfactant Brdnsted acids, and 13 promotes the aldol reaction in the presence of a base, whereas prolinamide 4, prepared by click stra-tegy, has been used for the first aldol reaction of thiazolecarbaldehyde with methyl-isopropyl ketone on water with excellent results. Phthalimido-prolinamide 12 is also effective in promoting aldol reactions in neat conditions. 

It is possible to increase the acidity of the carboxamide hydrogen by introduction of a sulfonyl substituent on the nitrogen atom such as in proline sulfonamides 15 (pi ra = 8-11). Examples of these include 15a-d, 15e and ISf, allq lsulfamides 15h, camphor-derived 

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