Synthesis 2010(4): 701-713  
DOI: 10.1055/s-0029-1218645
FEATUREARTICLE
© Georg Thieme Verlag Stuttgart ˙ New York

‘On Water’ Iminium/Enamine Catalysis: Organocatalytic Enantioselective Cyclopropanation of α,β-Unsaturated Aldehydes

Uxue Uria, Jose L. Vicario*, Dolores Badía, Luisa Carrillo, Efraim Reyes, Amaia Pesquera
Departamento de Química Orgánica II, Facultad de Ciencia y Tecnología, Universidad del País Vasco/Euskal Herriko Unibertsitatea, P.O. Box 644, 48080 Bilbao, Spain
Fax: +34(94)6012748; e-Mail: joseluis.vicario@ehu.es;
Further Information

Publication History

Received 11 November 2009
Publication Date:
12 January 2010 (online)

Abstract

We have developed a very efficient procedure for carrying out the cyclopropanation reaction of α,β-unsaturated aldehydes with diethyl bromomalonate using an O-TMS-diarylprolinol as a catalyst. We have found that the use of water as reaction medium results in a remarkable beneficial effect on the reaction, allowing it to be performed without the need to incorporate one equivalent of an external base, which is the case in other similar methodologies reported. In addition, several new chiral pyrrolidines have been prepared that have potential for improved ability as a catalyst for this transformation in aqueous media. In this context, a modified O-TMS-diarylprolinol incorporating a hydrophobic alkyl side chain has been identified as a promising catalyst for this reaction.