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■ Synthesis and Reaction of Novel Spiro Pyrazol-3-ones Containing Oxirane Moiety

Hayate Nagabuchi, Eiichi Masumoto, Fumi Okabe-Nakahara, and Hiroshi Maruoka*

*Faculty of Pharmaceutical Sciences, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan

Abstract

An efficient synthesis and reaction of a series of spiro pyrazol-3-one derivatives containing oxirane moiety are described. The convenient substrates, three types of pyrazole-4,5-diones, were reacted with phenacyl bromides in the presence of triethylamine in ethanol at room temperature to give the corresponding spiro epoxide-pyrazol-3-ones in moderate to good yields. Furthermore, thermal treatment of spiro compounds with pyrrolidine in the presence of water caused ring transformation easily to afford the corresponding pyridazinone derivatives. These methods provide several advantages such as operational simplicity, shorter reaction time, and higher yields. All the synthesized compounds were characterized by spectroscopic analysis.