DMT-2'-F-Bz-dA

40615-36-9

136834-20-3

136834-21-4

N-(9-((2R,3R,4R,5R)-3-fluoro-4-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl)-9H-purin-6-yl)benzamide (570 g, 1.53 mol) was dissolved in pyridine (2.85 L, 35.2 mol). The reaction mixture was cooled to 2.6 °C, followed by the addition of 4,4'-bimethoxytrityl chloride (543 g, 1.60 mol). The reaction mixture was stirred at 0 to 5 °C for 2 h and then slowly warmed to room temperature. The progress of the reaction was monitored by LC/MS and after confirming that the reaction was complete, the mixture was cooled below 5°C and the reaction was quenched by slow addition of methanol (124 ml, 3.05 mol) with continuous stirring for 15 min. Subsequently, the reaction mixture was concentrated by co-evaporation with toluene (2.00 L) and diluted with a solvent mixture of ethyl acetate (2.85 L) and n-heptane (2.85 L). The organic layer was washed with 9% saturated aqueous sodium bicarbonate (2.0 L) and ethyl acetate (2.85 L) was added to ensure complete dissolution of the crude product. After stirring for 5 minutes, the organic and aqueous layers were separated. After the organic layer was washed with water (2.0 L), solids began to slowly precipitate out. After separation of the aqueous layer, the organic layer was concentrated to approximately 1/50th of the original volume. the crude product was slurried with a solvent mixture of n-heptane (2.00 L) and toluene (0.50 L), stirred for 15 minutes, and then the light yellow solid was collected by vacuum filtration. The filter cake was washed sequentially with a solvent mixture of (1) n-heptane (0.60 L) and toluene (0.30 L) and (2) n-heptane (3.00 L). The solid was dried at room temperature for 30 min, then transferred to a tray and dried in a vacuum oven at 50 °C overnight to afford the target compound N-(9-((2R,3R,4R,5R)-5-((bis(4-methoxyphenyl)(phenyl)methoxy)methyl)-3-fluoro-4-hydroxytetrahydrofuran-2-yl)-9H-purin-6-yl)benzamide (996.7 g. 1.47 mol, 97% yield).NMR data confirmed the structure of the product.