1: 1.) CuI, (CH3)2S / 1.) THF, -20 deg C, 5 min, 2.) THF, a) -20 deg C, 15 min, b) RT, 15 min 2: o-chloranil / acetic acid / 8 h / Ambient temperature View Scheme

THF, -60.deg C, 1 h; Yield given. Multistep reaction. Yields of byproduct given;

in tetrahydrofuran T=-60°C; temp. change; Product distributionMechanism;