Au(i)-catalyzed and iodine-mediated cyclization of enynylpyrazoles to provide pyrazolo[1,5-a]pyridines
作者:Hung-Chou Wu、Chia-Wen Yang、Long-Chih Hwang、Ming-Jung Wu
DOI:10.1039/c2ob25973g
日期:——
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.
吡唑并[1,5-a]吡啶和6-
碘吡唑并[1,5-a]吡啶分别通过
金催化、
碘介导的烯丙基
吡唑环化反应合成,收率良好至极佳。
碘化加合物通过铃木-宫浦尔偶联反应进一步转化为6-芳基
吡唑并[1,5-a]吡啶,通过乌尔曼缩合反应转化为6-
氰基
吡唑并[1,5-a]吡啶。其中一种环化加合物2-(4-
氟苯基)
吡唑并[1,5-a]吡啶通过两步反应转化为p38激酶
抑制剂2-(4-
氟苯基)-3-(4-
吡啶基)
吡唑并[1,5-a]吡啶。