4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxyl; toluene-4-sulfonic acid in dichloromethane 1.) 0 deg C, 1h, 2.) room temp., 24 h;

1: 1. NaH / 1. THF, a.) 0 deg C to r.t., b.) r.t., 0.5 h; 2. a.) 0 deg C to r.t., b.) r.t., 17 h 3: 1. trifluoroacetic anhydride (TFFA), DMSO; 2. Et3N / 1. CH2Cl2, -60 deg C, 2 h; 2. a.) -60 deg C, 1.5 h, b.) -60 deg C to 20 deg C, 0.5 h, c.) 2 h 4: 87 percent / pyridine / CH2Cl2 / 15 h / Ambient temperature 5: 94 percent / 1,8-diazabicyclo<5.4.0>undec-7-ene (DBU) / tetrahydrofuran / 3 h / 50 °C View Scheme