title: Au(I)-catalyzed and iodine-mediated cyclization of enynylpyrazoles to provide pyrazolo[1,5-a]pyridines.
abstract: Pyrazolo[1,5-a]pyridines and 6-iodopyrazolo[1,5-a]pyridines were synthesized by gold-catalyzed and iodine-mediated cyclization of enynylpyrazoles in good to excellent yields, respectively. The iodinated adducts were further converted to 6-arylpyrazolo[1,5-a]pyridines via Suzuki-Miyaura coupling reaction and 6-cyanopyrazolo[1,5-a]pyridine by Ullmann condensation reaction. One of the cyclization adducts, 2-(4-fluorophenyl)pyrazolo[1,5-a]pyridine, was converted to a p38 kinase inhibitor, 2-(4-fluorophenyl)-3-(4-pyridinyl)pyrazolo[1,5-a]pyridine, in two steps.
authors: Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Taiwan.
authors: Hung-Chou
authors: HC
authors: Wu
authors: Chia-Wen
authors: CW
authors: Yang
authors: Long-Chih
authors: LC
authors: Hwang
authors: Ming-Jung
authors: MJ
authors: Wu
mesh_terms: D002384:Catalysis; D003500:Cyclization; D006046:Gold / Q000737:chemistry*; D054879:Halogenation; D007455:Iodine / Q000737:chemistry*; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011720:Pyrazoles; D011725:Pyridines; C447480:pyrazolo(3,4-b)pyridine; D006046:Gold; D007455:Iodine