(5R)-3-(3-Fluoro-4-iodophenyl)-5-[(4-hydroxymethyl-1H-1,2,3-triazol-1-yl)methyl]oxazolidin-2-one → 1-{[(5R)-3-(3-Fluoro-4-iodophenyl)-2-oxo-1,3-oxazolidin-5-yl]methyl}-1H-1,2,3-triazole-4-carbaldehyde

(5R)-3-(3-Fluoro-4-iodophenyl)-5-[(4-hydroxymethyl-1H-1,2,3-triazol-1-yl)methyl]oxazolidin-2-one (5.7 g, 13.6 mmol) and manganese oxide (3.56 g, 40.9 mmol) were mixed and heated up to 100° C. in dry 1,4-dioxane for 48 hours, then the mixture was cooled down to 70° C. and filtered through celite. The filtrate was concentrated and dissolved in 5% methanol in dichloromethane, hexaneses was added and the formed precipitates were filtered and collected as the title compound (3.6 g).