Brittany L. Gay, Lauren A. Prendeville, Ya-Nong Wang and Kami L. Hull*,
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Base-Free Borylation of Aryl Halides Enabled by Zn-Promoted Halide Abstraction
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 ≤82% isolated yields. 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 the reaction efficiency with electron-poor arenes.
期刊介绍:
Organic Letters invites original reports of fundamental research in all branches of the theory and practice of organic, physical organic, organometallic,medicinal, and bioorganic chemistry. Organic Letters provides rapid disclosure of the key elements of significant studies that are of interest to a large portion of the organic community. In selecting manuscripts for publication, the Editors place emphasis on the originality, quality and wide interest of the work. Authors should provide enough background information to place the new disclosure in context and to justify the rapid publication format. Back-to-back Letters will be considered. Full details should be reserved for an Article, which should appear in due course.