Synthesis 2015; 47(04): 549-561
DOI: 10.1055/s-0034-1379546
paper
© Georg Thieme Verlag Stuttgart · New York

Glyoxylic Acid versus Ethyl Glyoxylate for the Aqueous Enantio­selective Synthesis of α-Hydroxy-γ-Keto Acids and Esters by the N-Tosyl-(S a)-binam-l-prolinamide-Organocatalyzed Aldol Reaction

Fernando J. N. Moles
a   Departamento de Química Orgánica and Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain   Fax: +34(96)5903549   Email: gabriela.guillena@ua.es   Email: cnajera@ua.es
,
Gabriela Guillena*
a   Departamento de Química Orgánica and Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain   Fax: +34(96)5903549   Email: gabriela.guillena@ua.es   Email: cnajera@ua.es
,
Carmen Nájera*
a   Departamento de Química Orgánica and Instituto de Síntesis Orgánica, Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain   Fax: +34(96)5903549   Email: gabriela.guillena@ua.es   Email: cnajera@ua.es
,
Enrique Gómez-Bengoa*
b   Departamento de Química Orgánica I, Universidad del País Vasco, Apdo. 1072, 20080 San Sebastián, Spain   Email: enrique.gomez@ehu.es
› Author Affiliations
Further Information

Publication History

Received: 13 August 2014

Accepted after revision: 28 October 2014

Publication Date:
27 November 2014 (online)


Abstract

N-Tosyl-(S a)-binam-l-prolinamide is an efficient catalyst for the aqueous aldol reaction between ketones and glyoxylic acid, as the monohydrate or as an aqueous solution, or a 50% toluene solution of ethyl glyoxylate. These reactions led to the formation of chiral α-hydroxy-γ-keto carboxylic acids and esters in high levels of diastereo- and enantioselectivities (up to 97% ee), providing mainly anti aldol products. Only cyclopentanone and cyclohexane-1,4-dione afforded an almost 1:1 mixture of the syn/anti-diastereoisomers; however, the reaction between 4-phenylcyclohexanone and ethyl glyoxylate gave the corresponding syn,syn-product as the major diastereoisomer.

Supporting Information