AbstractThe quinolone–quinoline tautomerization is harnessed to effect the regioselective C8‐borylation of biologically important 4‐quinolones by using [Ir(OMe)(cod)]2 as the catalyst precursor, the silica‐supported monodentate phosphine Si‐SMAP as the ligand, and B2pin2 as the boron source. Initially, O‐borylation of the quinoline tautomer takes place. Critically, the newly formed 4‐(pinBO)‐quinolines then undergo N‐directed selective Ir‐catalyzed borylation at C8. Hydrolysis of the OBpin moiety on workup returns the system to the quinolone tautomer. The C8‐borylated quinolines were converted to their corresponding potassium trifluoroborate (BF3K) salts and to their C8‐chlorinated quinolone derivatives. The two‐step C‐H borylation‐chlorination reaction sequence resulted in various C8‐Cl quinolones in good yields. Conversion to C8‐OH‐, C8‐NH2‐, and C8‐Ar‐substituted quinolones was also feasible by using this methodology.
摘要 以[Ir(OMe)(cod)]2 为催化剂前体,以二氧化硅支撑的单齿膦 Si-SMAP 为配体,以 B2pin2 为硼源,利用喹啉-喹啉的共聚作用实现了对生物具有重要意义的 4-喹啉酮的区域选择性 C8-硼化。最初,喹啉同系物发生 O-硼化反应。重要的是,新形成的 4-(pinBO)-喹啉会在 C8 处发生 N 向选择性 Ir 催化的硼酸化反应。在工作过程中,OBpin 分子发生水解,使系统返回到喹啉酮同系物。C8 硼酰化的喹啉被转化为相应的三氟硼酸钾(BF3K)盐及其 C8 氯化喹啉酮衍生物。通过两步 C-H 玻里化-氯化反应顺序,可以得到各种 C8-Cl 喹啉酮,而且产率很高。利用这种方法还可以转化为 C8-OH-、C8-NH2- 和 C8-Ar 取代的喹诺酮。