Example 1
10 g (33.09 mmol) of 1-(2-fluoro-6-trifluoromethyl-benzyl)-6-methyl-1H-pyrimidine-2,4-dione (III), 6.8 g (49.62 mmol) of K2CO3 and 2.4 g (6.6 mmol) of tetrabutylammonium iodide were mixed with 50 mL of acetone at the temperature of about 20° C. Subsequently, 13.6 g (43.12 mmol) of (R)-2-((tert-butoxycarbonyl)amino)-2-phenylethyl methanesulfonate (IVa) were added and the obtained mixture was heated at the temperature of about 55° C. and maintained under stirring for about 16 hours at said temperature.
Once this maintenance was finished, the solvent was vacuum distilled and 50 mL of ethyl acetate and 50 mL of water were added to the residue thus obtained. A 1 M aqueous solution of HCl was slowly added, maintaining the temperature between 20 and 25° C. until achieving a pH of between 7 and 8. The aqueous phase was separated and treated with 3 fractions of 30 mL each of ethyl acetate. All the organic extracts were pooled and the solvent was removed by means of vacuum to obtain a slightly yellowish oily residue to which 45 mL of methanol were added, obtaining complete dissolution of the residue.
Example 2
16.1 g (99.24 mmol) of iodine monochloride (ICI) were dissolved in 40 mL of methanol at the temperature of about 10° C. The methanol solution previously obtained according to the methodology described in Example 1 comprising 3-((R)-2-(tert-butoxycarbonyl)amino-2-phenylethyl)-1-(2-fluoro-6-trifluoromethylbenzyl)-6-methyl-1H-pyrimidine-2,4-dione (II) was added to the iodine monochloride solution, maintaining the temperature between 20 and 25° C. Once the addition was finished, the obtained solution was heated to about 50° C. and was maintained under stirring for 2 hours at the mentioned temperature.
Once the maintenance was finished, the solvent was vacuum distilled and 50 mL of acetone were slowly added to the obtained oily residue at the temperature of between and 25° C. The addition of acetone caused a solid precipitate to appear almost immediately. The obtained mixture was maintained for 1 hour under stirring at the mentioned temperature. The resulting solid was isolated by filtration, washed with two fractions of 25 mL of acetone, and finally dried at the temperature of 50° C. to obtain 15.6 g (80.8% yield) of a white solid corresponding to the 3-((R)-2-(amino-2-phenylethyl)-1-(2-fluoro-6-trifluoromethylbenzyl)-5-iodo-6-methyl-1H-pyrimidine-2,4-dione hydrochloride salt (Ia) (UHPLC purity: 98.9%).
1H-NMR (d6-DMSO, 400 MHz) δ (ppm): 8.70 (2H, s broad), 7.65-7.48 (3H, m), 7.40-7.32 (5H, m), 5.40-5.29 (2H, dd), 4.47 (1H, t), 4.25 (2H, dd), 2.65 (3H, s).
13C-NMR (d6-DMSO, 100 MHz) δ (ppm): 161.87, 159.47, 159.41, 154.19, 150.98, 134.70, 129.93, 129.84, 129.01, 128.58, 127.38, 122.61, 122.34, 122.22, 121.34, 121.10, 74.80, 52.26, 45.45, 44.60, 25.66.
The DSC of this compound is shown in FIG. 1 and the XRPD is shown in FIG. 2.