title: Keratin Protein-Catalyzed Nitroaldol (Henry) Reaction and Comparison with Other Biopolymers.
abstract: 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.
authors: Institute of Organic Chemistry, University of Regensburg, Universitätsstr 31, Regensburg 93053, Germany. Marleen.Haering@chemie.uni-regensburg.de.|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. Marleen.Haering@chemie.uni-regensburg.de.
authors: Marleen
authors: M
authors: Häring
authors: Institute of Organic Chemistry, University of Regensburg, Universitätsstr 31, Regensburg 93053, Germany. asja.pettignano@enscm.fr.|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. asja.pettignano@enscm.fr.
authors: Asja
authors: A
authors: Pettignano
authors: 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. francoise.quignard@enscm.fr.
authors: Françoise
authors: F
authors: Quignard
authors: 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. nathalie.tanchoux@enscm.fr.
authors: Nathalie
authors: N
authors: Tanchoux
authors: Institute of Organic Chemistry, University of Regensburg, Universitätsstr 31, Regensburg 93053, Germany. David.Diaz@chemie.uni-regensburg.de.|IQAC-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain. David.Diaz@chemie.uni-regensburg.de.
authors: David
authors: D
authors: Díaz Díaz
mesh_terms: D002384:Catalysis; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D007633:Keratins / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; D009574:Nitro Compounds; D000644:Quaternary Ammonium Compounds; C560828:nitroaldol; D007633:Keratins; C009405:tetrabutylammonium
keywords: C-C bond formation; Henry reaction; biopolymer; keratin; nitroaldol reaction