The compound obtained in step h (0.54 g) was taken in acetonitrile (6 mL) and water (1 mL). To this solution, sodium dihydrogen phosphate (0.054 g) was added. The reaction mixture was cooled to 0° C. and hydrogen peroxide (1 mL) and sodium chlorite (0.208 g) were added. After stirring the reaction mixture for an additional 1 hour, the solvents were evaporated on a rotary evaporator; the residue was taken into water and extracted with ethyl acetate. The organic layer was washed with water and brine solution, and dried over anhydrous sodium sulphate. The solvent was evaporated under reduced pressure to get the title compound (0.5 g).
