Boron Trichloride Mediated Regioselective Claisen Rearrangement of Resorcinol­ Derivatives: Application to Resorcinol Carvonyl Ethers

Claisen rearrangement (CR) of resorcinol allyl ethers was examined. Although thermal CR gave low regioselectivity, the selectivity was much improved in the presence of a Lewis acid such as boron trichloride. This rearrangement was successfully applied to resorcinol carvonyl ethers for the regioselective introduction of a carvone unit into the resorcinol skeleton for the synthesis of phytoestrogenic miroestrols.