1: 65 percent / diphenyl diselenide, 70percent aq. tert-butyl hydroperoxide / benzene / 4.5 h / Heating 2: 1.) triphenylphosphine, 2.) K2CO3 / 1.) DME, reflux, 40 h, 2.) RT, 48 h View Scheme

potassium carbonate; triphenylphosphine 1.) DME, reflux, 40 h, 2.) RT, 48 h; Yield given. Multistep reaction;