Oxidation of Difluorocarbene by Pyridine N-Oxide and Ensuing Access to Carbamoyl Fluorides^†

A practical one-pot preparation of carbamoyl fluorides from easily obtained pyridine N-oxide, commercially available secondary amines and synthetically versatile difluorocarbene precursors (Ruppert-Prakash reagent or Chen's reagent) was developed herein, which dexterously resorted to the oxidation of difluorocarbene by external pyridine N-oxide to produce the toxic and gaseous fluorophosgene in situ. Notable features of this method include nice functionality tolerance, late-stage modification of drug molecules and the recovery and recycle of quinoline. (Figure presented.).