copper(I) bromide*diethyl sulfide in tetrahydrofuran -40 degC -> r.t., 10 min, reflux;

copper(I) bromide dimethylsulfide complex in tetrahydrofuran 0.5 h; Heating;

1.1: triethylamine / tetrahydrofuran / 20 h / 0 - 20 °C 1.2: 60 percent / NaH / tetrahydrofuran / 72 h / 20 °C 2.1: 78 percent / CuBr*SMe2 / tetrahydrofuran / 0.5 h / Heating View Scheme

1: 92 percent / Et3N / CH2Cl2 / 1) 0 deg C, 1 h, 2) room temperature, 4 h 2: 1) TsCl, Et3N, DMAP, 2) NaH / 1) CH2Cl2, 0 deg C to room temperature, overnight, 2) THF, 0 deg C to room temperature; room temperature, 24 h 3: 84 percent / CuBr*SEt2 / tetrahydrofuran / 1) -40 deg C to room temperature, 10 min, 2) reflux, 4 h View Scheme

1: 1) TsCl, Et3N, DMAP, 2) NaH / 1) CH2Cl2, 0 deg C to room temperature, overnight, 2) THF, 0 deg C to room temperature; room temperature, 24 h 2: 84 percent / CuBr*SEt2 / tetrahydrofuran / 1) -40 deg C to room temperature, 10 min, 2) reflux, 4 h View Scheme