boron trifluoride diethyl etherate; dimethylthio-dimethyl-tin; acetic acid 1.) toluene, 0 deg C, 5 h, 2.) 0 deg C, 30 min; Yield given. Multistep reaction. Yields of byproduct given;

1: 1.) Me2Sn(SMe)2, BF3*OEt2, 2.) AcOH / 1.) toluene, 0 deg C, 5 h, 2.) 0 deg C, 30 min View Scheme