Synthesis of coumestan derivatives via FeCl3-mediated oxidative ring closure of 4-hydroxy coumarins.

A concise and efficient approach to the syntheses of coumestan analogues has been developed. The underpinning strategy involves a FeCl(3)-mediated direct intramolecular oxidative annellation of 4-hydroxy-3-phenyl-2H-chromen-2-one derivatives. Utilizing this synthetic protocol, a variety of coumestan derivatives were conveniently obtained from readily available reagents.