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Insertion of CO 2 Mediated by a (Xantphos)Ni I –Alkyl Species
Author(s) -
Diccianni Justin B.,
Hu Chunhua T.,
Diao Tianning
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201906005
Subject(s) - xantphos , chemistry , alkyl , halide , medicinal chemistry , carboxylation , reductive elimination , stereochemistry , molecule , catalysis , inorganic chemistry , organic chemistry , aryl
Abstract 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.