M+H]+ 696.3072, found 696.3059. N4 -Acetyl-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl-3 ,five -O-M+H]+ 696.3072, discovered 696.3059. N4 -Acetyl-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl-3

M+H]+ 696.3072, found 696.3059. N4 -Acetyl-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl-3 ,five -O-
M+H]+ 696.3072, discovered 696.3059. N4 -Acetyl-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl-3 ,five -O-[(1,1,three,3tetraisopropyl-1,3-disiloxanediyl])-5-methyl-cytidine (13). Crude compound 12 (74.2 g) was dissolved in 371 mL dichloromethane. Acetic anhydride (20.1 mL, 212.6 mmol) was slowly added to the Reaction mixture and left to stir at ambient temperature for 23 h. Then, 100 mL of water was added towards the reaction mixture and stirred for 7 min followed by the addition of 400 mL sat. NaHCO3 . Following stirring to get a few minutes, the reaction mixture was transferred to a separating funnel, phases separated and organic phase washed () with sat. aq. NaHCO3 and water. Organic phase was dried more than Na2 SO4 , GS-626510 Epigenetics filtered and concentrated below reduced pressure. Obtained crude light orange foam 13 (66.six g) was applied for the subsequent step without the need of any further purification. 1 H NMR is presented within the Supplementary Components (Supplementary Figure S22). ES-MS calc. for C30 H50 F3 N5 O9 Si2 [M+H]+ 738.3177, identified 738.3159. N4 -Acetyl-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl]-5-methyl-cytidine (14). Crude compound 13 (65.eight g) was dissolved in 329 mL of acetonitrile, triethylamine ML-SA1 In stock trishydrofluoride (28 mL, 170 mmol) was added and also the reaction mixture was stirred at ambient temperature for 19 h. Precipitated product was filtered off, 400 mL of tertbutyl methyl ether was added for the filtrate as a co-solvent, left to stir more than a weekend and filtered once more. Solutions from each precipitations were pooled collectively, re-slurried in dichloromethane and left to stir overnight. The slurry was filtered to provide 17 g with the solution 14 (35 from eight). 1 H NMR (500 MHz, CD3 OD): = eight.45 (s, 1H), 5.93 (s, 1H), 4.42.28 (m, 2H), 4.25 (s, 1H), 4.10 (d, J = 8.five Hz, 1H), four.03 (d, J = 12.five Hz, 1H), three.98 (d, J = 5.0 Hz, 1H), 3.83 (d, J = 12.5 Hz, 1H), three.53.37 (m, 4H), two.39 (s, 3H), two.05 (s, 3H). 13 C NMR (202.47 MHz, CD3 OD): = 170.96, 156.75, 143.91, 117.97, 115.31, 93.87, 89.35, 84.31, 70.94, 69.49, 67.38, 62.64, 59.ten, 40.40, 37.43, 26.59, 24.79, 11.17. 19 F NMR (470.56 MHz, CD3 OD): = -77.36 ppm. ES-MS calc. for C18 H24 F3 N5 O8 [M+H]+ 496.1655, identified 496.1653. N4 -Acetyl-5 -O-(four,four -dimethoxytrityl)-2 -O-[(N-(trifluoroacetamidoethyl)carbamoyl)methyl]5-methyl-cytidine (15). Compound 14 (17.four g, 35.12 mmol)) was dried by co-evaporation with pyridine (), re-dissolved in pyridine (87 mL), cooled in an ice bath and 4,four -dimethoxytrityl chloride (12.5 g, 36.9 mmol) was added as a solid for the reaction option. After stirring the reaction mixture for three h in an ice bath, an additional portion of four,4 -dimethoxytrityl chloride (0.59 g, 1.8 mmol) was added and left to stir at RT for 16 h. Reaction was quenched with 200 of MeOH, then the reaction mixture was diluted with sat. aq. NaHCO3 and extracted with ethyl acetate. The organic phase was washed with sat. aq. NaHCO3 (), water and brine, dried more than NaSO4 and evaporated. Obtained crude pale foam was purified by way of flash chromatography (pre-equilibrated with 1 TEA in DCM) working with a gradient from 0 to 25 MeOH in DCM within the presence of 1 TEA. Compound 15 was obtained as a pale yellow foam just after evaporation of pure fractions. The foam was re-slurried in heptane to provide compound 15 as a white powder (20.1 g, 72 , 92 NMR assay, residual solvents present). 1 H NMR (500 MHz, CD OD): = 8.19 (s, 1H), 7.45 (d, J = 7.1 Hz, 2H), 7.36.17 (m, 7H), three six.84 (d, J = 9.0 Hz, 4H), 5.89 (d, J = 0.9 Hz, 1H), four.57 (dd, J = 9.1, 5.0 Hz, 1H), four.44.34 (m, two.