Insertion of CO 2 Mediated by a (Xantphos)Ni I –Alkyl Species

The incorporation of CO 2 into organometallic and organic molecules represents a sustainable way to prepare carboxylates. The mechanism of reductive carboxylation of alkyl halides has been proposed to proceed through the reduction of Ni II to Ni I by either Zn or Mn, followed by CO 2 insertion into...

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Bibliographic Details
Published in:Angewandte Chemie 2019-09, Vol.131 (39), p.14003-14006
Main Authors: Diccianni, Justin B., Hu, Chunhua T., Diao, Tianning
Format: Article
Language:English
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Summary:The incorporation of CO 2 into organometallic and organic molecules represents a sustainable way to prepare carboxylates. The mechanism of reductive carboxylation of alkyl halides has been proposed to proceed through the reduction of Ni II to Ni I by either Zn or Mn, followed by CO 2 insertion into Ni I ‐alkyl species. No experimental evidence has been previously established to support the two proposed steps. Demonstrated herein is that the direct reduction of ( t Bu‐Xantphos)Ni II Br 2 by Zn affords Ni I species. ( t Bu‐Xantphos)Ni I ‐Me and ( t Bu‐Xantphos)Ni I ‐Et complexes undergo fast insertion of CO 2 at 22 °C. The substantially faster rate, relative to that of Ni II complexes, serves as the long‐sought‐after experimental support for the proposed mechanisms of Ni‐catalyzed carboxylation reactions.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.201906005