Insitu Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines

Hua Cheng, Mao Qian Xiong, Chuan Xiang Cheng, Hua Jing Wang, Qiang Lu, Hong Fu Liu, Fu Bin Yao, Francis Verpoort, Cheng Chen

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, insitu generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active insitu catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=-7.8ppm in the 1HNMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the insitu generated catalyst system.

Original languageEnglish
Pages (from-to)440-448
Number of pages9
JournalChemistry - An Asian Journal
Volume13
Issue number4
DOIs
Publication statusPublished - 16 Feb 2018

Keywords

  • Amides
  • Atom economy
  • Carbenes
  • Reaction mechanisms
  • Ruthenium

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Insitu Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines'. Together they form a unique fingerprint.

  • Cite this