Synthesis, characterisation and application of pyridine-modified chitosan derivatives for the first non-racemic Cu-catalysed Henry reaction. (1st February 2018)

• Record Type: Journal Article
• Authors: Goncalves, Fernanda Jorge; Kamal, Fadwa; Gaucher, Anne; Gil, Richard; Bourdreux, Flavien; Martineau-Corcos, Charlotte; Gurgel, Leandro Vinícius Alves; Gil, Laurent Frédéric; Prim, Damien
• Is Part Of: Carbohydrate polymers. Volume 181(2018)
• Page Start: 1206
• Page End: 1212
• Publication Date: 2018-02-01
• Subjects: Modified chitosan -- Solid-state 13C NMR -- Heterogeneous catalysis -- Copper -- Henry reaction; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2017.12.012
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Pyridine-modified chitosan derivatives were applied in nitroaldol (Henry) reaction. Solid-state 13 C MC-CP MAS was applied to elucidate the catalyst structures. 47(±2)% of chitosan-free NH2 groups were grafted for both C1 and C2 catalysts. C1-Cu(OAc)2 provided a high conversion and the enantiomeric excess increased to 19(±4)%. C2-Cu(OAc)2 provided a higher conversion, but the enantiomeric excess was 14.5(±1.5)%. Abstract: The preparation, characterisation and application of two pyridine-modified chitosan derivatives (C1 and C2 ) containing Cu(OAc)2 adsorbed as catalysts for the conversion of benzaldehyde into 2-nitro-1-phenylethanol are described. Quantitative solid-state 13 C multiple-contact cross-polarization, magic-angle-spinning, nuclear magnetic resonance (MC-CP MAS NMR) measurements confirmed the successful grafting of 2-pyridinecarboxaldehyde and 6-methylpyridine-2-carboxaldehyde to the chitosan backbone and indicated that 47(±2)% of the NH2 groups were grafted for both C1 and C2 . The use of C1 -Cu(OAc)2 as a catalyst in the nitroaldol reaction led to 96(±1)% conversion and 19(±4)% enantiomeric excess (ee), while the use of C2 -Cu(OAc)2 as a catalyst also promoted the nitroaldol reaction, affording almost quantitatively the expected 2-nitro-1-phenylethanol (98(±1)%) with 14.5(±1.5)% ee.