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Alkyl boronic acids and esters are versatile synthetic intermediates that generally require several steps to synthesize. Three-component alkene arylboration reactions allow for the rapid synthesis of alkyl boronic esters. Herein, we report the base-free aerobic Pd-catalyzed three-component alkene arylboration, which allows direct access, in a single step, to alkyl boronic esters from readily available precursors: aryl boronic acids, alkenes, and bis(pinacol)diboron. This approach allows for the formal insertion of an alkene into an Ar–B bond, and thus, generates an alkyl boronic ester from an aryl boronic acid. The reaction proceeds with both electron-rich and electron-deficient aryl boronic acids as well as strained cyclic, internal, and terminal olefins. The reactions are regioselective: 1,2-arylboration products are formed with strained cyclic alkenes and b-alkyl-styrenes while 1,1-arylboration products are generated from terminal alkenes. Forty-five examples are presented with isolated yields of the resulting alkyl boronic esters ranging from 20-74%, along with several examples demonstrating the synthetic utility of the products. Mechanistic investigations support that the catalytic cycle occurs through direct arylboration of the alkene. Further, p-benzyl intermediates form when possible, and the rate of borylation is increased with electron-rich arenes relative to electron-poor. Finally, we demonstrate that aryl boroxines, generated in situ, are essential for the transformation as they rapidly undergo base-free transmetalation with the proposed palladium peroxo intermediate. 

We report the intramolecular 1,n-aminoboration for the simultaneous synthesis of aza-heterocycles with distal carbon–boron bonds. Pd-catalyzed remote 1,n-aminoboration occurs with 1,2-disubstituted alkenes; upon aminopalladation of the olefin, chain-walking generates the terminal Pd-alkyl intermediate which selectively undergoes Fe-catalyzed borylation. Terminal bishomoallylic amines, amides, carba-mates, and ureas afford the borylated pyrrolidines and lactams through 1,2-aminoboration. Forty-one examples of 1,n-borylated hetero-cycles are presented with yields up to 92% yield. Derivatization of the products is explored: cross-coupling, amination, and oxidation to access unnatural amino alcohols and acids. 

Herein we report the palladium-catalyzed borylation of aryl halides (iodides or bromides) under base-free conditions utilizing a commercially available Lewis acidic mediator, Zn(OTf)2. Under these conditions, an array of electronically and functional group-diverse aryl iodides and bromides undergo borylation to afford the corresponding aryl boronic esters in up to 82% isolated yield. Mechanistic investigations are consistent with Zn(OTf)2 enabling transmetalation between a cationic Pd(II)-Ar intermediate and B2pin2 via halide abstraction. Furthermore, stabilization of the cationic [ArPdII]+ complex with added [BArF4]– significantly improves reaction efficiency with electron-poor arenes. 

Aminoboration of simple alkenes with nitrogen nucleophiles remains an unsolved problem in synthetic chemistry; this transformation can be catalyzed by palladium via aminopalladation followed by transmetalation with a diboron reagent. However, this catalytic process faces inherent challenges with instability of the alkylpalladium(II) intermediate toward β-hydride elimination. Herein, we report a palladium/iron cocatalyzed aminoboration, which enables this transformation. We demonstrate these conditions on a variety of alkenes and norbornenes with an array of common nitrogen nucleophiles. In the developed strategy, the iron cocatalyst is crucial to achieving the desired reactivity by serving as a halophilic Lewis acid to release the transmetalation-active cationic alkylpalladium intermediate. Furthermore, it serves as a redox shuttle in the regeneration of the Pd(II) catalyst by reactivation of nanoparticulate palladium.