A new reagent system for installation of an aryl group onto the monoacetate of 4-cyclopentene-1,3-diol

Among the three types of reagents from PhMgX (X=Br, Cl) and CuCN for phenylation of 4-cyclopentene-1,3-diol monoacetate, PhMgCl/CuCN (cat.) and Ph2Cu(CN)(MgCl)2 in THF afforded the trans-1,4-isomer efficiently (82–87% yields, 91–93% regioselectivity). Similarly, o- and p-RC6H4MgCl (R=Me, OMe, CH2CH) in combination with CuCN furnished good to excellent reactivity and regioselectivity. As an application, a three-step synthesis of dihydromultifidene was accomplished successfully.