Unexpected transformations of 3-(bromoacetyl)coumarin provides new evidence for the mechanism of thiol mediated dehalogenation of α-halocarbonyls

Magwenzi, Faith N; Khanye, Setshaba D; Veale, Clinton G L

Title: Unexpected transformations of 3-(bromoacetyl)coumarin provides new evidence for the mechanism of thiol mediated dehalogenation of α-halocarbonyls
Creator: Magwenzi, Faith N
Creator: Khanye, Setshaba D
Creator: Veale, Clinton G L
Date Issued: 2017
Date: 2017
Type: text
Type: article
Identifier: http://hdl.handle.net/10962/66200
Identifier: vital:28916
Identifier: https://doi.org/10.1016/j.tetlet.2017.01.082
Description: publisher version
Description: The mechanism for the thiol mediated dehalogenation of α-halogenated carbonyls has remained an unresolved problem, despite its ongoing application in synthetic organic chemistry. Nakamura and co-workers first proposed that net dehalogenation occurs via sequential nucleophilic substitutions, while Israel and co-workers concluded that the rate at which dehalogenation occurred suggested that dehalogenation proceeds in a single concerted step. In this study, we investigated the debromination and nucleophilic substitution of 3-(bromoacetyl)coumarin with a variety of thiophenols, whose electron donating or withdrawing natures resulted in large variations in the degree of nucleophilic substitution and dehalogenation products, respectively. Results from these experiments, in addition to an unexpected formation of thioether containing dibenzo[b,d]pyran-6-ones from a Robinson annulation, has provided new evidence for this disputed mechanism.
Format: 5 pages
Format: pdf
Language: English
Relation: Tetrahedron Letters
Relation: Magwenzi, Faith N., Khanye, Setshaba D., Veale, Clinton G.L. (2017) Unexpected transformations of 3-(bromoacetyl)coumarin provides new evidence for the mechanism of thiol mediated dehalogenation of α-halocarbonyls. Tetrahedron Letters. 58 (10), p.968 – 972. SN: 0040-4039. https://doi.org/10.1016/j.tetlet.2017.01.082
Relation: Tetrahedron Letters volume 58 number 10 968 972 March 2017 0040-4039
Rights: Elsevier B.V.
Rights: Use of this resource is governed by the terms and conditions of the Tetrahedron Letters Open Access Options Statement (https://www.elsevier.com/journals/tetrahedron-letters/0040-4039/open-access-options)

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Veale, Clinton G L (Dr)

Khanye, David Setshaba (Associate Prof)

RU Department of Chemistry

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