1: chlorodurene With naphthalene; lithium in diethyl ether T=3 - 6°C; 3 h; 2: With copper (I) cyanide in tetrahydrofuran; diethyl ether T=3 - 6°C; 0.5 h; 3: oxalic acid monoethyl ester chloride in tetrahydrofuran; diethyl ether T=3 - 20°C; 1.33333 h; Cooling with ice;

1: 1,4-dichloro-2,3,5,6-tetramethylbenzene With naphthalene; lithium in diethyl ether T=20°C; 19 h; 2: oxalic acid monoethyl ester chloride in diethyl ether T=20°C; Cooling with liquid nitrogen;

1: 1,4-dichloro-2,3,5,6-tetramethylbenzene With lithium in diethyl ether T=20°C; 24 h; 2: oxalic acid monoethyl ester chloride in diethyl ether Overall yield = 1.51 g;