Decarboxylative Borylation: New Avenues for the Preparation of Organoboron Compounds

Abstract

The preparation of organoboron compounds has been widely explored and persistently pursued in organic chemistry. Recently, redox‐activated N‐hydroxyphthalimide carboxylic esters have been utilized as efficient feedstocks for decarboxylative borylation processes, enabling coupling between the abundant carboxylic acids and the versatile organoboron compounds. Here we highlight such advances, with an emphasis on clarifying the different working mechanisms for Ni‐catalyzed, light‐promoted, or organocatalytic decarboxylative borylative reactions.

Decarboxylation‐Initiated Intermolecular Carbon‐Heteroatom Bond Formation

“…Within the last two decades, a rapidly growing number of decarboxylative functionalization reactions have been disclosed based on these concepts. Most decarboxylative C−C couplings are covered by recent reviews, [7–29] but decarboxylative reactions with the formation of C‐heteroatom bonds are only considered on the sideline or limited to discussion on one specific C‐heteroatom bond [30–35] . Hence, this review aims at providing a comprehensive overview of decarboxylative heterofunctionalization, especially highlighting the progress made within the last decade until January 2021 (Scheme 2).…”

Integrated redox-active reagents for photoinduced regio- and stereoselective fluorocarboborylation

“…Due to the complexity of radical process incorporating C-C and C-B bonds formation, several issues need to be addressed, including the reactivities of carbon and boron-centered radicals, the regioselectivity of the radical additions to unsymmetrical alkynes, and stereoselectivity towards E/Z vinylboronates. Typically, a radical borylation process [25][26][27][28][29][30][31][32] often employs Lewis basic solvents/mediators such as DMAc 33,34 , DMF 19,35 , phthalimide 36 , and pyridine 37,38 for the activation of diboron reagents via homolytic cleavage of B-B bonds (Fig. 1b).…”

Cu-Catalyzed Decarboxylative Borylation

“… 5 Both methods employed RAEs and either a photoactive boron-donor (B 2 cat 2 ) in the case of the former method, or an Ir-based photocatalyst and B 2 pin 2 as the boron donor in the latter. These three complementary approaches 6 are clearly of use on a preparative scale, but for process applications, they all suffer certain drawbacks, such as the use of excess/expensive boron donors, low concentrations, or oxygen sensitivity. In addition, certain regions of the world prefer to avoid the use of homogeneous Ni catalysis on scale, 7 or expensive photocatalysts and continuous flow apparatus which add additional cost and engineering considerations.…”