toluene-4-sulfonic acid in acetic acid T=90°C;

boron trifluoride diethyl etherate in dichloromethane 72 h; Ambient temperature;

1: 1.) CuI, 2.) p-TsOH*H2O / 2.) molecular sieves (3 Angstroem) / 1a.) ether, -78 deg C, 1.5 h, 1b.) ice-bath, 1 h, 2.) benzene, 4 h at reflux 2: RhCl3*3H2O / ethanol; benzene / 28 h / Heating View Scheme

copper(l) iodide; toluene-4-sulfonic acid; 3 A molecular sieve 1a.) ether, -78 deg C, 1.5 h, 1b.) ice-bath, 1 h, 2.) benzene, 4 h at reflux; Yield given. Multistep reaction. Yields of byproduct given;