A Co₂B Mediated NaBH₄ Reduction Protocol Applicable to a Selection of Functional Groups in Organic Synthesis

Abstract

A high‐yielding and high‐rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi‐jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure.

Coolade. A Low‐Foaming Surfactant for Organic Synthesis in Water

“…N ‐(4‐Sulfamoylphenyl)acetamide ( 13 ): Reduction was conducted according to the procedure described in section 4.3 (Supporting Information) to give 13 as a white solid. Spectroscopic data matched that reported in the literature . R f =0.40 (MeOH/DCM 20:80).…”

“…Spectroscopic data matched that reported in the literature. [16] R f = 0.40 (MeOH/DCM 20:80). 90,142.20,138.07,126.67,118.43,69.79,39.52,24.12 ppm.…”

Reduction of Oximes and Hydrazones: Asymmetric and Diastereoselective Approaches

“…Sodium borohydride is a mild reducing agent making the combination of sodium borohydride with inorganic compounds such as transition metal complexes, iodine or sulfuric acid, sometimes required to reduce certain functional groups. This strategy has been used to reduce α-amino alcohols [63,64], alkenes [65,66], nitriles [67], nitro compounds [68,69], and others [70]. The reduction of 1-hydroxyiminophosphanates was also achieved using sodium borohydride in presence of molybdenum oxide or nickel chloride, giving amino phosphonic acids [71].…”

Selective Nitro Reduction of Ester Substituted Nitroarenes by NaBH4-FeCl2

“…21 However, for the reduction of some less-electronphilic functional groups, the reducibility of NaBH 4 needed to be enhanced by combining with transition metal catalysts. 22 23 24 25 26 27 28 29 30 Indeed, NaBH 4 combined transition metal such as Fe, 31 32 33 Co, 34 35 Ni 36 37 and Cu 38 39 are available for reducing nitroaromatics to the corresponding aromatic amines, nevertheless, these metal catalysts are associated with one or more problems such as necessity of using metal nanoparticles and was not commercially available, no assess the substrate scope, and poor selectivity, as it did in the case of the process development of vilazodone, of which the key intermediate ethyl 5-nitrobenzofuran-2-carboxylate ( 1a ) is envisioned to be reduced by NaBH 4 during our project development .…”