**23. Relay visible-light photocatalysis**

A relay visible-light photocatalysis strategy using formal 4+1 annulation and aromatization was achieved. Three successive photoredox cycles (one oxidative cycle and two reductive quenching cycles) were engaged in a reaction with one photocatalyst. Multiple quenching cycles could be demonstrated in a single reaction involving formal 4+1 annulation of hydrazone with 2-bromo diethylmalonate [23] (**Figure 30**).

**Figure 30.** *Relay VLPC.*
