Compound 494 (0.62 g, 1.66 mmol) was dissolved in acetone (14 mL). Concentrated HCl (37%, 0.69 mL, 8.3 mmol) was added and the solution was cooled on an ice bath. NaNO2 (0.14 g, 1.99 mmol) was dissolved in H2O (1 mL) and added to the above solution during 15 minutes. The internal temperature was kept at 0° C.-2° C. during the addition. The suspension was stirred on an ice bath for 0.5 h, after which a solution of KI (0.41 g, 2.45 mmol) and I2 (0.31 g, 1.22 mmol) in H2O (4 mL) was added drop wise during 5 minutes. The mixture was stirred at 0° C. for 2 h. H2O (20 mL) and EtOAc (20 mL) was added and stirred and the phases were separated. The organic phase was washed with aqueous NaHSO3, then with aqueous Na2CO3, dried (MgSO4), filtered and concentrated in vacuo. The crude product was purified by flash chromatography using EtOAc/petroleum ether (40-60) 1:5 to afford the title compound as a slightly coloured crystalline compound.
