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Communication | Regular issue | Vol 38, No. 1, 1994, pp.21-25
Published online, 1st January, 1970
DOI: 10.3987/COM-93-6548
A Convenient Synthesis of 2-Pyrazolines and Pyrazoles from Aldehyde Hydrazones and Ethyl Propiolate

Yasuhiro Kamitori, Masaru Hojo, Ryoichi Masuda,* Masaki Fujishiro, and Masaaki Wada

*Department of Industrial Chemistry, Faculty of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan


Aldehyde methylhydrazones (3) reacted with ethyl propiolate in the presence of acetic acid affording 4-ethoxycarbonyl-1-methyl-2-pyrazolines (4) in 13 - 44% yields. Easily 4 was dehydrated to the corresponding pyrazoles (6) by treatment with H2O2 in the presence of FeCl2.