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Palladium-Catalyzed Selective Five-Fold Cascade Arylation of the 12-Vertex Monocarborane Anion by B–H Activation


Lin, Furong; Yu, Jing-Lu; Shen, Yunjun; Zhang, Shuo-Qing; Spingler, Bernhard; Liu, Jiyong; Hong, Xin; Duttwyler, Simon (2018). Palladium-Catalyzed Selective Five-Fold Cascade Arylation of the 12-Vertex Monocarborane Anion by B–H Activation. Journal of the American Chemical Society, 140(42):13798-13807.

Abstract

A series of cage penta-arylated carboranes have been synthesized by palladium-catalyzed intermolecular coupling of the Ccarboxylic acid of the monocarba-closo-dodecaborate anion [CB11H12]− with iodoarenes by direct cage B−H bond functionalization. These transformations set a record in terms of one-pot directing group-mediated activation of inert bonds in a single molecule. The methodology is characterized by high yields, good functional group tolerance, and complete cage regioselectivity. The directing group COOH can be easily removed during or after the intermolecular coupling reaction. The mechanistic pathways were probed using density functional theory calculations. A Pd(II)−Pd(IV)−Pd(II) catalytic cycle is proposed, in which initial coupling is followed by preferred B−H activation of the adjacent boron vertex, and continuation of this selectivity results in a continuous walking process of the palladium center. The methodology opens a new avenue toward building blocks with 5-fold symmetry.

Abstract

A series of cage penta-arylated carboranes have been synthesized by palladium-catalyzed intermolecular coupling of the Ccarboxylic acid of the monocarba-closo-dodecaborate anion [CB11H12]− with iodoarenes by direct cage B−H bond functionalization. These transformations set a record in terms of one-pot directing group-mediated activation of inert bonds in a single molecule. The methodology is characterized by high yields, good functional group tolerance, and complete cage regioselectivity. The directing group COOH can be easily removed during or after the intermolecular coupling reaction. The mechanistic pathways were probed using density functional theory calculations. A Pd(II)−Pd(IV)−Pd(II) catalytic cycle is proposed, in which initial coupling is followed by preferred B−H activation of the adjacent boron vertex, and continuation of this selectivity results in a continuous walking process of the palladium center. The methodology opens a new avenue toward building blocks with 5-fold symmetry.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Uncontrolled Keywords:Colloid and Surface Chemistry, Biochemistry, General Chemistry, Catalysis
Language:English
Date:24 October 2018
Deposited On:11 Dec 2018 14:49
Last Modified:12 Dec 2018 08:32
Publisher:American Chemical Society (ACS)
ISSN:0002-7863
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1021/jacs.8b07872

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