1: 1.) N,N'-carbonyldiimidazole / 1.) DMF, acetonitrile, r.t., 1.5 h, 2.) r.t., overnight 2: 74 percent / p-carboxybenzenesulfonyl azide, TEA / ethyl acetate / 0.5 h / Ambient temperature 3: 74 percent / Rh2(OAc)4 / benzene / 0.05 h / Heating 4: N,N-diisopropylethylamine / acetonitrile / 1.5 h / -20 °C View Scheme