1: 90 percent / TFA / CH2Cl2 / 1 h / Ambient temperature 2: 75 percent / NaBH3CN / acetonitrile / 1 h / Ambient temperature 3: 93 percent / NaNO2 / acetic acid; acetic anhydride / 1.) 0 deg C, 16 h, 2.) room temperature, 8 h 4: 95 percent / CH2Cl2 View Scheme

1: 90 percent / TFA / CH2Cl2 / 1 h / Ambient temperature 2: 75 percent / NaBH3CN / acetonitrile / 1 h / Ambient temperature 3: 93 percent / NaNO2 / acetic acid; acetic anhydride / 1.) 0 deg C, 16 h, 2.) room temperature, 8 h View Scheme