1: (Z,Z)-1,4-diiodo-1,2,3,4-tetraphenyl-1,3-butadiene With tert.-butyl lithium in diethyl ether; pentane T=-78°C; 1 h; 2: With copper(l) chloride in diethyl ether; pentane T=-78°C; 0.5 h; 3: carbon monoxide With di-tert-butyl peroxide in diethyl ether; pentane T=0°C; P=760.051 Torr; 1 h; Further stages.;

copper(l) iodide; K2S in acetonitrile T=20°C; Ullmann coupling; Heating;