Synfacts 2009(3): 0325-0325  
DOI: 10.1055/s-0028-1087721
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Proline-Thiourea Self-Assemblies in Aldol Reactions

Contributor(s): Benjamin List, Lars Ratjen
Ö. Reis, S. Eymur, B. Reis, A. S. Demir*
Middle East Technical University, Ankara, Turkey
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Publikationsverlauf

Publikationsdatum:
19. Februar 2009 (online)

Significance

The proline-thiourea assembly-­catalyzed intermolecular aldol reaction of aromatic aldehydes with cyclohexanone is reported. The anti-configured products were obtained in high yields and exclusively excellent enantioselectivities. The reaction is proposed to proceed according to a modified Houk-List model, in which the carboxylate moiety of the proline forms an assembly with the thiourea, enhancing the reactivity and selectivity of the catalyst. Moreover, the thiourea acts as a nonpolar counterpart to proline, circumventing its solubility limits in unpolar solvents such as hexane or toluene.