in diethyl ether T=-78 - 21°C;

1: 85 percent / pyridinum p-toluenesulfonate / benzene / 15 h / Heating 2: 73 percent / EtONa / 1,2-dimethoxy-ethane / 48 h / Ambient temperature 3: 1.) NaH / 1.) ether, reflux, 2 h, 2.) ether, RT, overnight 4: 1.) copper(I) iodide, LiBr / 1.) ether, 0 deg C, 15 min, 2.) ether, -10 deg C, 12 h View Scheme

1: 99 percent / KHMDS / tetrahydrofuran / 1 h / -78 - 21 °C 2: 99 percent / diethyl ether / -78 - 21 °C View Scheme

1: 73 percent / EtONa / 1,2-dimethoxy-ethane / 48 h / Ambient temperature 2: 1.) NaH / 1.) ether, reflux, 2 h, 2.) ether, RT, overnight 3: 1.) copper(I) iodide, LiBr / 1.) ether, 0 deg C, 15 min, 2.) ether, -10 deg C, 12 h View Scheme

1: 60 percent / LDA, HMPA / tetrahydrofuran / 0.5 h / -78 °C 2: 99 percent / KHMDS / tetrahydrofuran / 1 h / -78 - 21 °C 3: 99 percent / diethyl ether / -78 - 21 °C View Scheme

1: 1.) NaH / 1.) ether, reflux, 2 h, 2.) ether, RT, overnight 2: 1.) copper(I) iodide, LiBr / 1.) ether, 0 deg C, 15 min, 2.) ether, -10 deg C, 12 h View Scheme

copper(l) iodide; lithium bromide 1.) ether, 0 deg C, 15 min, 2.) ether, -10 deg C, 12 h; Yield given. Multistep reaction;

in diethyl ether Yield given;

trifluoroacetic acid in chloroform T=21°C; 72 h;