1: lithium 2,2,6,6-tetramethylpiperidide / tetrahydrofuran; diethyl ether / 1 h / -107 °C 2: tetrahydrofuran; diethyl ether / 4 h / -78 °C View Scheme

1: lithium 2,2,6,6-tetramethylpiperidide / tetrahydrofuran; diethyl ether / 1 h / -107 °C 2: 50 percent / (Cl2CBr)2 / tetrahydrofuran; diethyl ether / -107 °C View Scheme