General procedure for the synthesis of 5,6,7,8-tetrahydro-8-hydroxyquinolines from 2-chloro-5,6,7,8-tetrahydroquinolin-8-ol: a generalized method was employed using PdCl2 (dppf), PdCl2 (tbpf), or (A.caPhos) PdCl2 as catalyst. First, the halogenated heterocyclic compound (0.66 mmol) was dissolved in anhydrous THF (13.2 mL) and degassed by drumming argon for a few minutes. Subsequently, PdCl2 (dppf) (27.0 mg, 0.033 mmol, 5.0 mol%), TMEDA (0.130 g, 1.12 mmol, 1.7 equiv) and NaBH4 (42.4 mg, 1.12 mmol, 1.7 equiv) were added sequentially. The reaction mixture was stirred under argon protection at room temperature for an appropriate time, after which it was post-treated as described above.
