1: 90 percent / CF3COOH / CH2Cl2 / 0.5 h / Ambient temperature 2: 1) HgCl2, CaCO3 2) Na2S*9H2O / 1) CH3CN, H2O, r.t., 1 h, 2) CHCl3, r.t., 1 h View Scheme

With  trifluoroacetic acid in  dichloromethane 0.5 h;  Ambient temperature;