Imidazole → 5-amino-3-[(2R,3R,5S)-5-[[tert-butyl(dimethyl)silyl]oxymethyl]-3-hydroxy-tetrahydrofuran-2-yl]-6H-thiazolo[4,5-d]pyrimidine-2,7-dione

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Reaction Steps

To a solution of 5-amino-3-[(2R,3R,5S)-3-hydroxy-5-(hydroxymethyl)tetrahydrofuran-2-yl]-6H-thiazolo[4,5-d]pyrimidine-2,7-dione (compound 38b, 3.8 g, 12.7 mmol) in DMF (30 mL) was added imidazole (2.6 g, 38 mmol) and tert-butylchlorodimethylsilane (4.2 g, 28 mmol) with stirring. After being stirred at room temperature for 2 hours, the resulting solution was diluted by EtOAc (200 mL), washed with water, brine, dried over Na2SO4. The organic layer was concentrated in vacuo and the residue was purified by column chromatography on silica gel (eluting with 1:5 EtOAc in petroleum ether) to afford 3.3 g of 5-amino-3-[(2R,3R,5S)-5-[[tert-butyl(dimethyl)silyl]oxymethyl]-3-hydroxy-tetrahydrofuran-2-yl]-6H-thiazolo[4,5-d]pyrimidine-2,7-dione (compound 38d).

Provenance & Evidence