Oxoammonium salts. Part 8: Oxidations in base: oxidation of O-1 unprotected monosaccharides to lactones using 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate

The oxidant, 4-acetylamino-2,2,6,6-tetramethylpiperidine-oxoammonium tetrafluoroborate in pyridine/CH2Cl2, is reported to be an excellent reagent for the conversion of hemiacetals to lactones. Specifically, the conversion of 1-O unprotected sugars to their corresponding aldonolactones is achieved in high yields. The basic reaction conditions partially overcome some disadvantages reported for oxoammonium-type oxidants, namely the inability to run the reaction in the presence of acid-labile groups and in the presence of β-oxygens.