BPO-promoted direct oxidative C-H functionalization of unactivated alkanes into 6-alkyl-6H-benzo[c]chromenes under transition-metal-free conditions.

A simple and efficient BPO-promoted free radical-based cascade reaction of biaryl vinyl ethers with easily available unactivated alkanes has been developed. A series of 6-alkyl-6H-benzo[c]chromenes have been successfully obtained in moderate to high yields under transition-metal-free conditions. This method can also be utilized to synthesize 6-alkyl-6H-benzo[c]thiochromenes from the corresponding biaryl vinyl thioethers.