and the solution was added dropwise over a period of 15 minutes. The reaction mixture was stirred in the ice bath for 1 h and stirred at room temperature overnight, and reaction mixture was quenched with aqueous solution of HCl and extracted with dichloromethane (50 mL X 2), and the organic layer was washed with water (100 mL), saturated sodium bicarbonate solution (100 mL), water (100 mL), brine (100 mL), dried over anhydrous MgSO4 and filtered. All volatiles were removed and the residue was purified using column chromatography (15:85