Aryl-bromine bonds are successfully cleaved by cobalt(II) porphyrins in basic media to give Co(por)Ar (por = porphyrin) in good yields. Mechanistic studies suggested that the aryl-bromine bond is cleaved through a halogen atom transfer mechanism, which is different from the aryl-halogen bond cleavage mechanism with other group 9 metalloporphyrins.
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http://dx.doi.org/10.1039/c4dt00155a | DOI Listing |
Org Lett
November 2024
Department of Organic and Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Stable hypervalent bromine(III) compounds were synthesized via aryl bromine oxidation with -hybridized nitrogen cations generated by oxime N-O bond cleavage in trifluoroacetic acid. The resulting intramolecular N-Br hypervalent bond is effectively stabilized by the planar xanthone structure. The structures and physicochemical properties of these λ-bromanes were characterized by X-ray crystallography, cyclic voltammetry, UV-vis spectroscopy, and computational analysis.
View Article and Find Full Text PDFAcc Chem Res
February 2015
School of Chemistry, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
CONSPECTUS: Transition metal-catalyzed organic transformations often reveal competing reaction pathways. Determining the factors that control the selectivity of such reactions is of extreme importance for the design of reliable synthetic protocols. Herein, we present the account of our studies over the past decade aimed at understanding the selectivity of reductive elimination chemistry of organotransition metal complexes under electrophilic halogenation conditions.
View Article and Find Full Text PDFOrg Biomol Chem
October 2014
Department of Chemistry, University of Wisconsin, 1101 University Ave., Madison, Wisconsin 53706, USA.
A copper(I) catalyzed 1,3-halogen migration/borylation migrates a bromine from an sp(2) carbon to a benzylic carbon with concomitant borylation of the aryl-bromine bond. This transformation proceeds via an aryl copper intermediate which can be accessed independently and then trapped with electrophiles. As such, copper-catalyzed 1,3-halogen migration provides unique and mild access to an aryl copper species that allows for rapid aromatic functionalization from an unconventional starting material.
View Article and Find Full Text PDFDalton Trans
June 2014
Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People's Republic of China.
Aryl-bromine bonds are successfully cleaved by cobalt(II) porphyrins in basic media to give Co(por)Ar (por = porphyrin) in good yields. Mechanistic studies suggested that the aryl-bromine bond is cleaved through a halogen atom transfer mechanism, which is different from the aryl-halogen bond cleavage mechanism with other group 9 metalloporphyrins.
View Article and Find Full Text PDFOrg Lett
May 2013
Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.
A hydroxymethylation reaction of a variety of iodoarenes proceeded effectively in the presence of CO, NHC-borane, diMeImd-BH3 (2) as a radical mediator, and a catalytic amount of AIBN. The reaction took place chemoselectively at the aryl-iodine bond but not at the aryl-bromine and aryl-chlorine bonds. A three-component coupling reaction comprising aryl iodides, CO, and electron-deficient alkenes also proceeded well to give unsymmetrical ketones in good yields.
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