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Communication | Regular issue | Vol 24, No. 10, 1986, pp.2771-2775
Published online, 1st January, 1970
DOI: 10.3987/R-1986-10-2771
Reaction of 2-Bromo-2,3-dihydro-1H-pyrazolo[1,2-a]indazolium Bromides with Alkaline Solution

Yasuo Fujimura,* Yoshiharu Nawata, and Masatomo Hamana

*Central Research Laboratories, Chugai Pharmaceutical Company, Ltd., Takada 3-41-8, Toshima-ku, Tokyo 171, Japan


Treatment of 2-bromo-2,3-dihydro-1H-pyrazolo[1,2-a]indazolium bromides (1a-c) with alkaline solution initially affords 9H-pyrazolo[1,2-a]indazolium bromides (2a-c), which are further convertible by dehydrobromination into pyrazolo[1,2-a]indazoles (3a-c). The 9-position of 3 is susceptible to attack by oxygen and acetyl cation.