N,N,N',N',N'',N''-hexamethylphosphoric triamide; samarium diiodide in tetrahydrofuran -78 deg C to r.t.;

Multi-step reaction with 3 steps 1: 88 percent / NEt3 / toluene / 1.) reflux, 30 min, 2.) r.t., overnight2: HBF4 / diethyl ether / 0.33 h / Ambient temperature3: 23 percent / CH2Cl2 / 16 h / Ambient temperature