Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
Giampiero Proietti, Kaniraj Jeya Prathap, Xinchen Ye, Richard T. Olsson, Peter Dinér*
*Department of Chemistry, School of Engineering Sciences in Chemistry, Biology and Health, KTH - Royal Institute of Technology, Teknikringen 30, 10044 Stockholm, Sweden,
Email: diner
kth.se
G. Proietti, K. J. Prathap, X. Yu, R. T. Olsson, P. Dinér, Synthesis, 2022, 54, 133-146.
DOI: 10.1055/a-1579-2190
see article for more reactions
Abstract
A nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed facile reductions of a wide range of nitroarenes, aliphatic nitro compounds, and organic azides. Addition of modified nanocellulose enabled lower catalyst loading in nitro reductions. The protocols are compatible with a one-pot Boc-protection to provide the corresponding carbamates.
see article for more examples
Reduction of Aromatic Azido Compounds; General Procedure
To a 5-mL sealed vial equipped with a magnetic stir bar, a solution containing azido compound (1 equiv, 0.15 mM) in deoxygenated MeOH, NiCl2·6H2O (0.5 mol%), and NaBH4 (2.5 equiv) were added. The mixture was stirred at rt for 3 h protected from light. After completion of the reaction, the crude obtained upon solvent removal under reduced pressure, was re-dissolved in water and extracted with Et2O or EtOAc, leaving the catalyst in the aqueous phase. The organic layer was dried (Na2SO2), and the pure product was obtained upon in vacuo solvent removal. All compounds were characterized by 1H and 13C NMR spectroscopy.
Tandem Reduction and Boc-Protection of Aliphatic Azido Compounds; General Procedure
To a 5-mL sealed vial equipped with a magnetic stir bar, a solution containing azido compound (1 equiv, 0.15 mM) in deoxygenated MeOH, NiCl2·6H2O (0.5 mol%), Boc2O (1.2 equiv), and NaBH4 (2.5 equiv) were added. The mixture was stirred at rt for 3 h protected from light. After completion of the reaction, the crude obtained upon solvent removal under reduced pressure was purified via flash column chromatography (petroleum ether/EtOAc) to afford the pure product. All compounds synthesized herein are known in the literature. Proof of purity and identity was obtained by 1H, 13C, and 19F NMR spectroscopy.
Key Words
nitro reduction, azide reduction, nickel borohydride, sodium borohydride, boc-protected amines, TEMPO nanocellulose, crystalline nanocellulose
ID: J66-Y2022
