Tetra-n-propylammonium tetra-oxoruthenate(VII): a reagent of choice for the oxidation of diversely protected glycopyranoses and glycofuranoses to lactones

2,3,4,6-Tetra- O -benzyl- d -glucopyranose, 2,3,5-tri- O -allyl- d -ribofuranose, 2,3,5-tri- O -allyl- and -tri- O -benzyl- d -arabinofuranose, and 2-deoxy-3,5-di- O -allyl- d - erythro -pentofuranose were oxidized to their corresponding lactones 6–10 by dimethyl sulfoxide activated by oxalyl chloride, pyridinium dichromate in the presence of molecular sieves and acetic acid, and tetra- n -propylammonium tetra-oxoruthenate(VII) using 4-methylmorpholine N -oxide as cooxidant. With the latter reagent, analytically pure lactones were obtained in 83–98% yield. A multistep preparation of 3,4,6-tri- O -benzyl-2-deoxy- d - arabino -hexono-1,5-lactone ( 14 ) from 3,4,6-tri- O -benzyl-1,5-anhydro-2-deoxy- d - arabino -hex-1 enitol (65% overall yield) is described.