An inexpensive, powerful, and eco-friendly method for transition-metal-free oxidative C(sp3)−H bond lactonization was developed using sodium peroxydisulfate as the sole oxidant. The cyclization of 2-alkylbenzoic acids containing a primary, secondary or tertiary carbon at the benzylic position proceeded smoothly, affording a variety of lactone derivatives. Furthermore, various functional groups such as halogen, cyano, nitro and hydroxy groups were tolerated under the reaction conditions.
- C−H functionalization
- radical cyclization
- transition-metal free synthesis