Insertion of CO2 Mediated by a (Xantphos)NiI–Alkyl Species. Issue 39 (14th August 2019)

• Record Type: Journal Article
• Authors: Diccianni, Justin B.; Hu, Chunhua T.; Diao, Tianning
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 39(2019)
• Page Start: 13865
• Page End: 13868
• Publication Date: 2019-08-14
• Subjects: carbon dioxide -- nickel -- reaction mechanisms -- reduction -- structure elucidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201906005
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The incorporation of CO2 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 CO2 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 Br2 by Zn affords Ni I species. ( t Bu‐Xantphos)Ni I ‐Me and ( t Bu‐Xantphos)Ni I ‐Et complexes undergo fast insertion of CO2 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. Abstract : Gathering support : The incorporation of CO2 into organometallic and organic molecules represents a sustainable way to prepare carboxylates. Demonstrated herein is that the direct reduction of ( t Bu‐Xantphos)Ni II Br2 by Zn affords Ni I species. ( t Bu‐Xantphos)Ni I ‐Me and ( t Bu‐Xantphos)Ni I ‐Et complexes undergo fast insertion of CO2 at 22 °C, providing experimental support for the proposed mechanisms of Ni‐catalyzed carboxylation reactions.