A mixture of N-benzyl-N-(4-bromo-3-oxobutyl)-2-nitrobenzenesulfonamide (16 g, 36.3 mmol) and potassium acetate (8.90 g, 91 mmol) in acetic acid (130 ml) was heated to 110-115° C. (slow reflux visible) and stirred for 1 hour (complete by HPLC). Cooled, acetic acid (80 ml) removed under reduced pressure, the residue distributed between DCM (120 ml) and water (120 ml). The organic phase was washed with water, evaporated to half of the volume, diluted with 2-propanol (65.0 ml), the rest of DCM removed. Water (18.20 ml) was added followed by concentrated hydrochloric acid (2.102 ml, 25.4 mmol), residual DCM was distilled off at atmospheric pressure until head temperature reached 77° C., then stirred under reflux for 3 hours. Diluted with water (65 ml), 2-propanol removed at 60° C./180 mbar, to the biphasic residue EA (80 ml) was added followed by sodium bicarbonate with stirring until evolution of gas stopped. The organic phase was dried (MgSO4), evaporated to dryness to give N-benzyl-N-(4-hydroxy-3-oxobutyl)-2-nitrobenzenesulfonamide (13.2 g, 34.9 mmol, 96% yield).
