1: 1.) trifluoroacetic anhydride (TFAA), 2.) aq. NaHCO3 / acetonitrile / 1.) 0 deg C, 10 min, 2.) RT, 4 h 2: 1,8-diazabicyclo<5.4.0>undec-7-ene (DBU) / 3 h / Ambient temperature View Scheme