Molecules 2014, 19(5), 5876-5897; doi:10.3390/molecules19055876
Article

Cobalt-Catalyzed Methoxycarbonylation of Substituted Dichlorobenzenes as an Example of a Facile Radical Anion Nucleophilic Substitution in Chloroarenes

1, 1, 2 and 1,* email
Received: 9 April 2014; in revised form: 26 April 2014 / Accepted: 28 April 2014 / Published: 6 May 2014
(This article belongs to the Special Issue Carbonylation Chemistry)
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: A thorough mechanistic study on cobalt-catalysed direct methoxycarbonylation reactions of chlorobenzenes in the presence of methyl oxirane on a wide range of substrates, including poly- and monochloro derivatives with multiple substituents, is reported. The results demonstrate that the reaction is potentially useful as it proceeds under very mild conditions (t = 62 °C, PCO = 1 bar) and converts aryl chlorides to far more valuable products (especially ortho-substituted benzoic acids and esters) in high yields. This transformation also offers another opportunity for the utilization of environmentally harmful polychlorinated benzenes and biphenyls (PCBs). This study is the first to discover an unexpected universal positive ortho-effect: the proximity of any substituent (including Me, Ph, and MeO groups and halogen atoms) to the reaction centre accelerates the methoxycarbonylation in chlorobenzenes. The effect of the ortho-substituents is discussed in detail and explained in terms of a radical anion reaction mechanism. The advantages of the methoxycarbonylation as a model for the mechanistic study of radical anion reactions are also illustrated.
Keywords: cobalt-catalysed methoxycarbonylation; aryl chlorides; synthesis of substituted benzoic acids; radical anion nucleophilic substitution; ortho-effect
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MDPI and ACS Style

Khaibulova, T.S.; Boyarskaya, I.A.; Larionov, E.; Boyarskiy, V.P. Cobalt-Catalyzed Methoxycarbonylation of Substituted Dichlorobenzenes as an Example of a Facile Radical Anion Nucleophilic Substitution in Chloroarenes. Molecules 2014, 19, 5876-5897.

AMA Style

Khaibulova TS, Boyarskaya IA, Larionov E, Boyarskiy VP. Cobalt-Catalyzed Methoxycarbonylation of Substituted Dichlorobenzenes as an Example of a Facile Radical Anion Nucleophilic Substitution in Chloroarenes. Molecules. 2014; 19(5):5876-5897.

Chicago/Turabian Style

Khaibulova, Tatyana S.; Boyarskaya, Irina A.; Larionov, Evgeny; Boyarskiy, Vadim P. 2014. "Cobalt-Catalyzed Methoxycarbonylation of Substituted Dichlorobenzenes as an Example of a Facile Radical Anion Nucleophilic Substitution in Chloroarenes." Molecules 19, no. 5: 5876-5897.


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