in dichloromethane dropwise addn. of a 0.1 M soln. of BCl3 in CH2Cl2 to a soln. of furan in CH2Cl2 at room temp. under N2; addn. of Na2CO3 soln. to finish reaction, extn. with ether, drying org. phase (MgSO4), evapn. of solvent, chromy. (SiO2, hexane/ether);