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Molecules 2016, 21(9), 1122;

Keratin Protein-Catalyzed Nitroaldol (Henry) Reaction and Comparison with Other Biopolymers

Institute of Organic Chemistry, University of Regensburg, Universitätsstr 31, Regensburg 93053, Germany
Institute Charles Gerhardt Montpellier-UMR 5253 CNRS/UM/ENSCM, Matériaux Avancés pour la Catalyse et la Santé, 8 rue de l'École Normale, Cedex 5, Montpellier 34296, France
IQAC-CSIC, Jordi Girona 18–26, Barcelona 08034, Spain
Author to whom correspondence should be addressed.
Academic Editor: Christophe Len
Received: 15 July 2016 / Revised: 2 August 2016 / Accepted: 2 August 2016 / Published: 25 August 2016
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Here we describe a preliminary investigation on the ability of natural keratin to catalyze the nitroaldol (Henry) reaction between aldehydes and nitroalkanes. Both aromatic and heteroaromatic aldehydes bearing strong or moderate electron-withdrawing groups were converted into the corresponding β-nitroalcohol products in both DMSO and in water in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. Negligible background reactions (i.e., negative control experiment in the absence of keratin protein) were observed in these solvent systems. Aromatic aldehydes bearing electron-donating groups and aliphatic aldehydes showed poor or no conversion, respectively. In general, the reactions in water/TBAB required twice the amount of time than in DMSO to achieve similar conversions. Moreover, comparison of the kinetics of the keratin-mediated nitroaldol (Henry) reaction with other biopolymers revealed slower rates for the former and the possibility of fine-tuning the kinetics by appropriate selection of the biopolymer and solvent. View Full-Text
Keywords: keratin; biopolymer; C-C bond formation; nitroaldol reaction; Henry reaction keratin; biopolymer; C-C bond formation; nitroaldol reaction; Henry reaction

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Häring, M.; Pettignano, A.; Quignard, F.; Tanchoux, N.; Díaz Díaz, D. Keratin Protein-Catalyzed Nitroaldol (Henry) Reaction and Comparison with Other Biopolymers. Molecules 2016, 21, 1122.

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