New Synthesis Method of New Nickel Reagent and Boric Acid (Ester)

Boric acid (ester) is an important molecular synthesis block, especially special boric acid (ester) such as heterocyclic ring, allyl, saturated hydrocarbon and substrate containing two functional groups, are popular blocks in synthetic chemistry.

In 2019, JACS published an article by Professor Melanie S. Sanford describing the method of synthesizing boric acid (ester) directly from acid, which is illustrated as follows:

JACS 2019 Oct 16. doi: 10.1021/jacs.9b08961

Advantages of this method

Ni-catalyzed decarbonylative borylation of carboxylic acid fluorides

• base-free conditions, highly selective towards borylation

• general, compatible with various boronic esters and boronamides

• abundant carboxylic acids as substrates

• trans-metalation-active intermediate as an air-stable catalyst

• mechanistic studies present trends in trans-metalation reactivities of Ar-Ni-F complexes with organoboron and diboron reagents

Experimental method

General procedure for decarbonylative borylation reaction (in situ, from carboxylic acid): In a nitrogen-filled glovebox, carboxylic acid (0.3 mmol, 1 equiv), TFFH (0.3 mmol, 1 equiv), and proton sponge (0.3 mmol, 1 equiv) were weighed into a 10 mL tall vial equipped with a 10 μm magnetic stir bar. THF (0.5 mL) was added, and the reaction mixture was stirred at room temperature for 15 to 30 min. Catalyst B (0.03 mmol, 0.1 equiv) and diboron reagent (0.6 mmol, 2 equiv) were added. The vial was capped and removed from the glovebox. The reaction mixture was stirred at 115 oC for 16 h. The reaction was then cooled to room temperature, and Et2O (10 mL) and saturated NaHCO3 (10 mL) were added. The organic layer was collected, and the aqueous solution was further extracted with Et2O (2×10 mL). The combined organic extracts were dried over Na2SO4 and concentrated in vacuo. The crude product was purified by flash column chromatography on silica gel using EtOAc in hexanes.

Examples of reactions

Building blocks may be applicable for the method

References

1. Christian A. Malapit, James R. Bour, Simon R. Laursen, and Melanie S. Sanford, J. Am. Chem. Soc. 2019, 141, 43, 17322–17330. https://doi.org/10.1021/jacs.9b08961

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