Decarboxylative halogenation, or halodecarboxylation, represents one of the fundamental key methods for the synthesis of ubiquitous organic halides. The method is based on conversion of carboxylic acids to the corresponding organic halides via selective cleavage of a carbon-carbon bond between the skeleton of the molecule and the carboxylic group and the liberation of carbon dioxide. In this review, we discuss and analyze major approaches for the conversion of alkanoic, alkenoic, acetylenic, and (hetero)aromatic acids to the corresponding alkyl, alkenyl, alkynyl, and (hetero)aryl halides. These methods include the preparation of families of valuable organic iodides, bromides, chlorides, and fluorides. The historic and modern methods for halodecarboxylation reactions are broadly discussed, including analysis of their advantages and drawbacks. We critically address the features, reaction selectivity, substrate scopes, and limitations of the approaches. In the available cases, mechanistic details of the reactions are presented, and the generality and uniqueness of the different mechanistic pathways are highlighted. The challenges, opportunities, and future directions in the field of decarboxylative halogenation are provided.
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http://dx.doi.org/10.1021/acs.chemrev.0c00813 | DOI Listing |
Molecules
December 2024
College of Environmental and Chemical Engineering, Dalian University, Dalian 116622, China.
-Butyl hypochlorite was employed as a versatile reagent for chlorooxidation of indoles, chlorination of 2-oxindoles, and decarboxylative chlorination of the indole-2-carboxylic acids. Four types of products including 2-chloro-3-oxindoles, 2,2-dichloro-3-oxindoles, 3,3-dichloro-2-oxindoles, and 2,3-dichloroindoles could be selectively obtained in moderate to excellent yields by switching the substrates. Various synthetically useful functional groups, such as halogen atoms, cyano, nitro, and methoxycarbonyl groups, remain intact during the reactions.
View Article and Find Full Text PDFOrg Lett
January 2025
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
ACS ES T Water
December 2024
Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, South Carolina 29625, United States.
Sci Adv
December 2024
Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China.
The [Fe]/HO oxidation system has found wide applications in chemistry and biology. Halogenation with this [Fe]/HO oxidation protocol and halide (X) in the biological system is well established with the identification of heme-iron-dependent haloperoxidases. However, mimicking such halogenation process is rarely explored for practical use in organic synthesis.
View Article and Find Full Text PDFEnviron Pollut
January 2025
State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, College of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China; State Environmental Protection Key Laboratory of Environmental Health Impact Assessment of Emerging Contaminants, Shanghai Academy of Environmental Sciences, Shanghai, 200233, PR China. Electronic address:
Heptafluoropropylene oxide dimer acid (HFPO-DA), as an alternative to perfluorooctanoic acid (PFOA), has been shown to pose similar environmental and health risks as other perfluorinated compounds. The electrochemical-based advanced oxidation processes are promising techniques for the treatment of perfluorinated compounds, and the boron-doped diamond (BDD) anode could degrade HFPO-DA under mild conditions. However, the roles of radicals in the degradation and how to overcome the steric hindrance of the -CF branch on the carboxyl group were not yet clear.
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