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Abstract The transition‐metal‐catalyzed Suzuki‐Miyaura cross‐coupling (SMC) reaction of organoboron nucleophiles with aryl (pseudo)halide electrophiles is a reliable method for carbon‐carbon bond formation. This reaction generally requires the use of an exogenous base to promote transmetalation process, which limits the substrate scope of the reaction due to undesired protodeboronation and functional group incompatibilities. Here, we established a base‐free SMC reaction via a conceptually different electrophilic substitution transmetalation (EST). This transformation is applicable to a wide range of base‐sensitive and sterically hindered organoborons. Key to this advance is the formation of a stable cationic palladium(II) or nickel(II) intermediate via experimental and theoretical investigations. In a broader context, this research further expands the synthetic boundary of cross‐coupling chemistry.
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Palladium and Iron Cocatalyzed Aerobic Alkene Aminoboration
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.
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- Award ID(s):
- 2155133
- PAR ID:
- 10526522
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- Journal of the American Chemical Society
- Volume:
- 145
- Issue:
- 34
- ISSN:
- 0002-7863
- Page Range / eLocation ID:
- 18939 to 18947
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/jacs.3c05790
