Chinese Journal of Catalysis ›› 2019, Vol. 40 ›› Issue (8): 1153-1159.DOI: 10.1016/S1872-2067(19)63352-8

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Silver-catalyzed carboxylative cyclization of alkynic hydrazones with carbon dioxide

Wenzhen Zhang, Yuqian Sun, Min Zhang, Hui Zhou, Xiaobing Lu   

  1. State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 110624, Liaoning, China
  • Received:2019-01-29 Revised:2019-03-09 Online:2019-08-18 Published:2019-06-21
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (21878038), the Natural Science Foundation of Liaoning Province (20170540156), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT-17R14).

Abstract: The development of new catalytic methodologies to synthesize heterocyclic fine chemicals using carbon dioxide as a synthon has attracted considerable attention. Herein, we report the silver(I)-catalyzed carboxylative cyclization of a variety of alkynic hydrazones with carbon dioxide to produce the corresponding 1,3,4-oxadiazin-2-ones under mild reaction conditions. In this reaction, silver(I) salts play a π-Lewis acid role for the highly efficient activation of the alkyne moiety in the hydrazone substrates. Single-crystal X-ray analysis and NOE experiments confirm that the newly formed oxadiazinone products exhibit Z configuration. Based on control experiments and NMR studies, a mechanism including the formation of a reactive carbazate intermediate, electrophilic cyclization, and subsequent protonation is proposed. This study offers an efficient and atom-economical method for the synthesis of biologically important 1,3,4-oxadiazin-2-ones.

Key words: Carbon dioxide, Silver catalysis, Carboxylative cyclization, Alkynic hydrazine, Oxadiazinone, Homogeneous catalysis