Organoboron reagents are widely used in organic chemistry due to their versatile reactivity, ubiquity, stability and, low cost. They are commonly employed as coupling partners in cross-coupling reaction such as the palladium-catalysed Suzuki-Miyaura reaction, which is responsible for 40% of C–C bond formation reactions in the pharmaceutical industry. However, with the development of the photoredox chemistry over the last 15 years, radical-mediated cross-coupling reactions have flourished. Radicals are now easily made from cheap-commercially-available or easy-to-make precursors using visible light irradiation. They can then further react with numerous different coupling partners leading to an extensive range of new cross coupling opportunities, without the requirement for a photocatalyst in some cases.&lt;font size="1"&gt; &lt;/font&gt;N-(Acyloxy)phthalimides (NHPI esters), a class of redox activated ester species, are widely used as alkyl radical precursors owing to their bench-stability and ease of access. Single electron transfer (SET) affords the desired radical through decarboxylation. In this work, we disclose a new method for C–C bond formation between an alkenylboronic acid and NHPI ester under ruthenium photocatalysis. The reaction proceeds smoothly within three hours under blue LED irradiation and affords the desired products in good to excellent yields. The radical-polar crossover reaction requires the presence of a redox-active additive to enable the desired bond formation to occur, and proceeds via an unusual boronic acid priming event. This presentation will describe the development and application of this reaction.

Photocatalytic c(sp3)–c(sp2) radical-polar crossover cross-coupling of alkenylboronic acids

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