Regioselective and Catalyst-Free Epoxidation of ( E )-3-[3-(2-Hydroxyaryl)-3-oxoprop-1-en-1-yl]chromones

摘要

The uncatalyzed reaction of hydrogen peroxide with (E)-3-[3-(2-hydroxyaryl)-3-oxoprop-1-en-1-yl] chromones resulted in a regioselective epoxidation of the chromone intracyclic C(2)= C(3) double bond to afford unique isomeric (E)-7a-[3-(2-hydroxyphenyl)-3-oxoprop-1-en-1-yl]-1aH-oxireno[2,3-b] chromen-7(7aH)-ones in high yields. 2D NMR and single-crystal X-ray diffraction were used to elucidate the structures of the chromanone epoxides. Density functional theoretical studies demonstrated a high electrophilicity of the starting chromones.