1: 54 percent / 1)NaH / benzene; dimethylformamide / 1) 50 deg C, 2) 4h, 50 deg C; 2d, r.t. 2: 71 percent / Na2CO3 / H2O / 8 h / Heating 3: 99 percent / tetrahydrofuran 4: 83.5 percent / BF3-etherate, tetraethylammoniumbromide / CHCl3 / 10 h / Heating 5: 67 percent / 6 h / Heating View Scheme

1: 1) Zn, BrCH2CH2Br, 3) CuCN, LiCl / 1) THF, 5 deg C, 3 h, 2) THF, -75 to -20 deg C, 3) THF, -70 deg C to RT, 14 h 2: 96 percent / K2CO3, MeOH / 1 h / Ambient temperature 3: 80 percent / pyridine / CH2Cl2 / 3 h / 0 °C View Scheme