Silver trifluoromethanesulphonate (9.39 g, 36.56 mmol) was added in a single batch to a solution of (3S)-3-amino-1-methyl-3-[3-[4-methyl-6-[4-(trifluoromethyl)phenyl]-pyrimidin-2-yl]prop-2-ynyl]pyrrolidin-2-one (which may be prepared as described in Description 14a) (71 g, 182.81 mmol) in MeCN (1000 mL) and the reaction was heated at 80° C. for 22 hours. The solvent was evaporated and the residue dissolved in DCM (1000 mL). Saturated NaHCO3 (500 ml) and water (500 ml) were added and the mixture shaken. The phases were separated and the organic layer treated with a solution of cysteine (100 g, 825.35 mmol) in water (1500 ml). This mixture was stirred vigorously for 30 minutes. The mixture was filtered through a pad of celite, and the celite washed with DCM (2×100 ml). The phases were separated and the organic layer placed in a large beaker. To this was added a solution of cysteine (50 g, 412.68 mmol) in water (500 ml) and the mixture was stirred for a further 30 minutes. The phases were separated and the organic layer was washed with a mixture of sat. brine (500 ml) and water (500 ml). The organic layer was dried (MgSO4) and the solvent evaporated to afford a dark brown foam. To the foam was added acetone (50 ml) and almost immediately a thick precipitate formed. This was swirled for about 5 minutes prior to slow addition of Et2O (150 ml) over approx. 10 minutes. After addition, the suspension was left to stand for 30 minutes. The solid was filtered off and washed with ether (3×30 ml) to afford the title material as a light brown solid (D15a) (49.24 g), pure by NMR and consistent with that produced by Method 1;
