Scheme 5.

Examination of the substrate scope. Reaction conditions: 1 (1.5 mmol), 2 (2.25 mmol), Pd(OAc)₂ (5 mol %), PPh₃ (10 mol %), TEA (1.8 mmol), TBAB (5 mol %), and NaBr (10.0 g) were placed in an 80 mL stainless steel vessel along with 207 stainless-steel balls (d_MB = 6 mm, Ф_MB = 0.293), milling at 800 rpm for 90 min. ^aN-Boc-3-bromoindazole was used as substrate. ^b150 min. ^c700 rpm. ^d3-chloro-1-methyl-1H-indazole was used as substrate, ν_rot = 900 rpm. ^e1,8-Bis(dimethylamino)naphthalene was used as base.