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Paper | Special issue | Vol 103, No. 1, 2021, pp.284-299
Published online, 22nd May, 2020
DOI: 10.3987/COM-20-S(K)13
■ 3-Trifluoromethanesulfonyloxy-4,7-dihydropyrazolo[1,5-a]pyridine via Ring-Closing Metathesis: Synthesis and Transformation to Withasomnine Homologs

Yoshihide Usami,* Yuya Tatsui, Kodai Sumimoto, Ayami Miyamoto, Nanase Koito, Hiroki Yoneyama, and Shinya Harusawa

*Laboratory of Pharmaceutical Organic Chemistry, Organic Pharmaceutical Chemistry Laboratory, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan

Abstract

3-Trifluoromethanesulfonyloxy-4,7-dihydropyrazolo[1,5-a]pyridine (9) was successfully synthesized from the starting material, pyrazole, via a sequence of reactions containing ring-closing metathesis as a key step. Suzuki-Miyaura coupling of 9 with various arylboronic acids, followed by oxidation or hydrogenation, readily afforded pyrazolo[1,5-a]pyridines (11) or 3-aryl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridines (12), respectively. Compounds 12 were found to be withasomnine homologs