2: trifluoroacetic acid / dioxane; H2O 3: sodium borohydride / ethanol 4: hydrogen / palladium black / acetic acid View Scheme

1: saturated sodium bicarbonate / diethyl ether / 18 h / Ambient temperature 2: 89 percent / trifluoroacetic acid / H2O; dioxane / 24 h 3: 1.) barium carbonate, Br2; 2.) Pd black, H2 / 1.) 3:1 dioxane-water, r.t., 36 h; 2.) acetic acid-water, 48 h; View Scheme