Nickel-Catalyzed Direct Alkylation of Terminal Alkynes at Room Temperature: A Hemilabile Pincer Ligand Enhances Catalytic Activity

Direct coupling of alkyl halides with terminal alkynes provides an efficient and streamlined access to alkyl-substituted alkynes, which are important synthetic intermediates, biologically active molecules, and organic materials. However, until now,there have been fewer than a handful of catalytic me...

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Bibliographic Details
Published inACS catalysis Vol. 5; no. 2; pp. 1164 - 1171
Main Authors Pérez García, Pablo M, Ren, Peng, Scopelliti, Rosario, Hu, Xile
Format Journal Article
LanguageEnglish
Published American Chemical Society 06.02.2015
Subjects
Sonogashira coupling
nickel
alkylation
alkynylation
kinetics
pincer complex
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Summary:Direct coupling of alkyl halides with terminal alkynes provides an efficient and streamlined access to alkyl-substituted alkynes, which are important synthetic intermediates, biologically active molecules, and organic materials. However, until now,there have been fewer than a handful of catalytic methods available for this reaction, and detailed mechanistic studies have not been reported. Herein, we describe the design and development a new nickel pincer complex that catalyzes the direct coupling of primary alkyl halides with terminal alkynes at room temperature. The catalysis has a good substrate scope and high functional group tolerance. Kinetic data suggest that the new pincer ligand is hemilabile, and the dissociation of a labile amine donor is the turnover-determining step of the catalysis. An intermediate Ni-alkynyl species has been isolated and structurally characterized. The reactivity of this species gives insight into the nature of the active species for the activation of alkyl halide.
ISSN:2155-5435
2155-5435
DOI:10.1021/cs501502u