CO2 = CO + O: Redox-Neutral Lactamization and Lactonization of C–H Bonds with CO2

Carbon dioxide, a nontoxic, cheap and readily available greenhouse gas, acts as the ideal carbonyl source with similar function as the combination of CO and oxidants ('CO₂ = CO + O'). We highlight this concept with recent advances of the lactamization and lactonization of C–H bond with CO₂ under redox-neutral or even transition-metal-free conditions.