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J Am Chem Soc. 2017 Sep 13;139(36):12524-12532. doi: 10.1021/jacs.7b05802. Epub 2017 Aug 29.

Helical Oligourea Foldamers as Powerful Hydrogen Bonding Catalysts for Enantioselective C-C Bond-Forming Reactions.

Author information

1
Univ. Bordeaux, CNRS, CBMN, UMR 5248, Institut Européen de Chimie et Biologie , 2 rue Robert Escarpit, F-33607 Pessac, France.
2
Departamento de Química Orgánica I, Facultad de Químicas, Universidad del País Vasco UPV/EHU , Apdo. 1072, 20080 San Sebastián, Spain.
3
Univ. Bordeaux, CNRS, INSERM, UMS3033/US001, Institut Européen de Chimie et Biologie , F-33607 Pessac, France.

Abstract

Substantial progress has been made toward the development of metal-free catalysts of enantioselective transformations, yet the discovery of organic catalysts effective at low catalyst loadings remains a major challenge. Here we report a novel synergistic catalyst combination system consisting of a peptide-inspired chiral helical (thio)urea oligomer and a simple tertiary amine that is able to promote the Michael reaction between enolizable carbonyl compounds and nitroolefins with excellent enantioselectivities at exceptionally low (1/10 000) chiral catalyst/substrate molar ratios. In addition to high selectivity, which correlates strongly with helix folding, the system we report here is also highly amenable to optimization, as each of its components can be fine-tuned separately to increase reaction rates and/or selectivities. The predictability of the foldamer secondary structure coupled to the high level of control over the primary sequence results in a system with significant potential for future catalyst design.

PMID:
28783369
DOI:
10.1021/jacs.7b05802
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