To a solution of ethyl 1-[5-[2-(3-ethyl-5-methyl-2-oxo-1,3,5-triazinan-1-yl)-7-hydroxy-1,3-benzothiazol-5-yl]pyrimidin-2-yl]-4-methyl-piperidine-4-carboxylate (533 mg, 0.593 mmol), dicesium carbonate (390 mg, 1.19 mmol) and N,N-dimethylformamide (10 mL) at 0° C. was added MeI (55 μL, 0.89 mmol) and the reaction mixture was allowed to warm to rt before stirring for 1 hr. A further portion of MeI (110 μL, 1.78 mmol) was added and the mixture stirred at rt for a further 18 hrs. The reaction was diluted with ammonium chloride solution (50 mL) and EtOAc (50 mL). The organic layer was separated and the aqueous layer washed with further portions of EtOAc (2×50 mL). The organic layers were combined, dried (MgSO4) and concentrated in vacuo to give crude product mixture followed by flash chromatography (12 g silica column), eluting with 0-100% EtOAc gradient in n-heptane to give the desired product (226 mg, light brown solid). 1H NMR (CDCl3) δ 8.63 (s, 2H), 7.51 (d, J=1.3 Hz, 1H), 6.82 (d, J=1.3 Hz, 1H), 5.23 (s, 2H), 4.42 (dt, J=13.6, 4.0 Hz, 2H), 4.35 (s, 2H), 4.25 (q, J=7.1 Hz, 2H), 4.04 (s, 3H), 3.56-3.50 (m, 2H), 3.43-3.34 (m, 2H), 2.70 (s, 3H), 2.25 (d, J=13.6 Hz, 2H), 1.58-1.48 (m, 2H), 1.38-1.24 (m, 9H). MS: 554.1 [M+H]+.
