Fig. 8: The substrate scope for natural products and their derivatives.

Reaction conditions: (1) 1as (0.36 mmol), 2 (0.30 mmol), BF₃·OEt₂ (0.30 mmol), toluene (2 mL), 90 °C, 30 min. (2) styrene (0.36 mmol), 2 (0.30 mmol), BF₃·OEt₂ (0.30 mmol), toluene (2 mL), rt, 4 h.