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Metal- And Additive-Free Photoinduced Borylation of Haloarenes

Adelphe M Mfuh, Brett D Schneider, Westley Cruces, Oleg V Larionov

Nat Protoc. 2017 Mar;12(3):604-610.

PMID: 28230850

Abstract:

Boronic acids and esters have critical roles in the areas of synthetic organic chemistry, molecular sensors, materials science, drug discovery, and catalysis. Many of the current applications of boronic acids and esters require materials with very low levels of transition metal contamination. Most of the current methods for the synthesis of boronic acids, however, require transition metal catalysts and ligands that must be removed via additional purification procedures. This protocol describes a simple, metal- and additive-free method of conversion of haloarenes directly to boronic acids and esters. This photoinduced borylation protocol does not require expensive and toxic metal catalysts or ligands, and it produces innocuous and easy-to-remove by-products. Furthermore, the reaction can be carried out on multigram scales in common-grade solvents without the need for reaction mixtures to be deoxygenated. The setup and purification steps are typically accomplished within 1-3 h. The reactions can be run overnight, and the protocol can be completed within 13-16 h. Two representative procedures that are described in this protocol provide details for preparation of a boronic acid (3-cyanopheylboronic acid) and a boronic ester (1,4-benzenediboronic acid bis(pinacol)ester). We also discuss additional details of the method that will be helpful in the application of the protocol to other haloarene substrates.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP864754198 1-(Thiophen-2-ylmethyl)-1H-pyrazole-4-boronic acid pinacol ester 1-(Thiophen-2-ylmethyl)-1H-pyrazole-4-boronic acid pinacol ester 864754-19-8 Price
AP99770931 1,4-Benzenediboronic acid bis(pinacol) ester 1,4-Benzenediboronic acid bis(pinacol) ester 99770-93-1 Price
LS77973 4,4′-Biphenyldiboronic acid bis(pinacol) ester 4,4′-Biphenyldiboronic acid bis(pinacol) ester Price
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