Figure 2:

a) Products are obtained as a separable mixture of the [3+2] cycloadduct 4 and C–H insertion products 5 favoring the isomer indicated unless otherwise stated. The isolated yield of only the dihydroindole product(s) given. The ¹H NMR yield of cycloadduct 4 determined from the crude reaction mixture is given in parenthesis. See the Supporting Information for combined isolated amounts of both 4 and 5 b) Conditions 50.0 mg (0.171 mmol) triazole 1a, 4 equiv arene 3, 0.50 M at 70 °C in CHCl₃ for 90 min. c) Mixtures of dihydroindole regioisomers are inseparable by column chromatography d) Performed with 1.00 mmol triazole 1b e) No ring-opened isomers (5) were detected by ¹H NMR analysis.