1: 82 percent / 33percent hydrobromic acid / CH2Cl2; acetic acid / 0.5 h / 0 °C 2: 91 percent / mercury<II> cyanide / CH2Cl2 / 2 h / Ambient temperature 3: dimethyl malonate / Pd(PPh3)4 / tetrahydrofuran / 24 h / Ambient temperature 4: pyridine View Scheme

1: 82 percent / 33percent hydrobromic acid / CH2Cl2; acetic acid / 0.5 h / 0 °C 2: 87 percent / acetic acid / 0.75 h / Ambient temperature 3: 95 percent / 5 Angstroem molecular sieves / trimethylsilyl triflate / CH2Cl2 / 12 h / -35 °C 4: dimethyl malonate / Pd(PPh3)4 / tetrahydrofuran / 24 h / Ambient temperature 5: pyridine View Scheme