carbon tetrabromide; triphenylphosphine Inert atmosphereSchlenk technique;

1: 61 percent / CBr4, Ph3P / tetrahydrofuran / 1 h 2: 1.) K2CO3, 18-crown-6-ether / 1.) acetone, reflux, 0.5 h, 2.) acetone, reflux, 42 h 3: 83 percent / CBr4, Ph3P / tetrahydrofuran / 2 h View Scheme

1: 1.) K2CO3, 18-crown-6-ether / 1.) acetone, reflux, 0.5 h, 2.) acetone, reflux, 42 h 2: 83 percent / CBr4, Ph3P / tetrahydrofuran / 2 h View Scheme