Preparation of chitosan-supported urea materials and their application in some organocatalytic procedures

Gonzalo de Gonzalo; Antonio Franconetti; Rosario Fernández; José M Lassaletta; Francisca Cabrera-Escribano

doi:10.1016/j.carbpol.2018.07.009

Preparation of chitosan-supported urea materials and their application in some organocatalytic procedures

Carbohydr Polym. 2018 Nov 1:199:365-374. doi: 10.1016/j.carbpol.2018.07.009. Epub 2018 Jul 5.

Authors

Gonzalo de Gonzalo¹, Antonio Franconetti², Rosario Fernández³, José M Lassaletta⁴, Francisca Cabrera-Escribano³

Affiliations

¹ Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, C/ Profesor García González 1, 41012 Sevilla, Spain. Electronic address: gdegonzalo@us.es.
² Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, C/ Profesor García González 1, 41012 Sevilla, Spain; Departament de Química, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Spain. Electronic address: Antonio.Franconetti@uab.cat.
³ Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, C/ Profesor García González 1, 41012 Sevilla, Spain.
⁴ Instituto de Investigaciones Químicas (CSIC-US) and Centro de Innovación en Química Avanzada (ORFEO-CINQA), Avda. Américo Vespucio, 49, 41092 Sevilla, Spain.

PMID: 30143140
DOI: 10.1016/j.carbpol.2018.07.009

Abstract

An efficient and mild procedure was developed for the preparation of three chitosan-supported ureas containing electron-withdrawing groups. These catalysts were characterized and employed as organocatalysts in different transformations, including the enantioselective cyanosilylation of α-ketoesters and aldehydes, the asymmetric addition of formaldehyde tert-butyl hydrazone to prochiral α-ketoesters and a Friedel-Crafts reaction. Several parameters that can affect the activity and selectivity of the reactions were analysed. The supported catalysts can be reused for more than 10 cycles with only a small loss in their properties. Finally, theoretical DFT calculations were carried out to interpret the results of the catalysed reactions.

Keywords: 4-Chlorobenzaldehyde (PubChem CID: 7726); Acetophenone (PubChem CID: 7410); Benzaldehyde (PubChem CID: 240); Chiral tertiary alcohols; Chitosan-supported ureas; Cyanosilylation; DFT calculations; Ethyl 2-oxo-4-phenybutyrate (PubChem CID: 562087); Ethyl benzoylformate (PubChem CID: 15349); Heterogeneous catalysis; Indole (PubChem CID: 798); Organocatalysis; Trimethylsilyl cyanide (PubChem CID: 82115); p-Nitrophenol (PubChem CID: 980); tert-Butylhydrazine hydrochloride (PubChem CID: 81889); trans-β-Nitrostyrene (PubChem CID: 5284459).