methanesulfonyl chloride; copper(I) bromide; lithium bromide in tetrahydrofuran T=-70 - 25°C;

1: 1-Bromo-2-butyne With indium in N,N-dimethyl-formamide T=20°C; 1 h; 2: chloro-trimethyl-silane in N,N-dimethyl-formamide T=20°C; 3 h;

1: 74.3 g / Et3N3 / CH2Cl2 / 1.) -50 deg C, 0.5 h, 2.) to 25 deg C, 1.5 h, 3.) 25 deg C, 0.5 h 2: CuBr*LiBr / tetrahydrofuran; diethyl ether / 1.) -60 deg C, 1 h, 2.) 25 deg C, 2 h View Scheme

LiCuBr2 in tetrahydrofuran; diethyl ether 1.) -60 deg C, 1 h, 2.) 25 deg C, 2 h; Yield given;