Synthesis of 9-O-arylated berberines via copper-catalyzed CAr-O coupling reactions.

Berberine is a widely used antimicrobial agent in clinic. However, a high dosage is often required due to its low lipophilicity and bioavailability. The current study explores the structural modifications of berberines with potentially lipophilic aryl groups to address this problem. A series of 15 9-O-aryl-substituted berberines (3a-o) and one 9-O-phenylene-bridged berberine dimer (5) was synthesized by copper-catalyzed cross-coupling of tetrahydroberberrubine and aryl iodides, followed by oxidation with I2.