Fig. 3 Intramolecular oxidative [4 + 2] annulation with respect to alkynes. Reaction conditions: styrene-yne 6 (0.2 mmol), Acr + -Mes ClO 4 − (3 mol%), Co (dmgH) 2 py 2 PF 6 (8 mol%) in DCE (14 mL), 3W blue LEDs, 24 h; isolated yields are shown