Phenyl thioxochloroformate → ((2S,3R,5S)-3-(benzoyloxy)-5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)tetrahydrofuran-2-yl)methyl benzoate

Participants

Reaction Steps

To a solution of 1-(3,5-di-O-benzoyl-β-L-arabinofuranosyl)uracil 12 (5.2 g, 11.4 mmoL) in anhydrous 1,2-dichloroethane (120 mL) were added phenoxythiocarbonyl chloride (4.7 mL, 34.3 mL) and 4-(dimethylamino)pyridine (DMAP, 12.5 g, 102.6 mmoL). The resulting solution was stirred at room temperature under argon atmosphere for 1 h and then evaporated under reduced pressure. The residue was dissolved in dichloromethane (300 mL) and the organic solution was successively washed with an ice-cold 0.2 N hydrochloric acid solution (3×200 mL) and water (2×200 mL), dried over Na2SO4 then evaporated under reduced pressure. The crude material was co-evaporated several times with anhydrous dioxane and dissolved in this solvent (110 mL). To the resulting solution were added under argon tris-(trimethylsilyl)silane hydride (4.2 mL, 13.7 mmol) and α,α′-azoisobutyronitrile (AIBN, 0.6 g, 3.76 mmol). The reaction mixture was heated and stirred at 100° C. for 1 h under argon, then cooled to room temperature and evaporated under reduced pressure. The residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (0-5%)] to give 13 (2.78 g, 56%) which was crystallized from EtOH: mp=223-225° C.; H-NMR (DMSO-d6): δ 11.4 (br s, 1H, NH), 8.0-7.5 (m, 11H, 2CH6H5CO, H-6), 6.28 (t, 1H, H-1′, J=7 Hz), 5.5 (m, 2H, H-1′ and H-5), 4.6-4.4 (m, 3H, H-4′, H-5′ and H-5″), 2.6 (m, 2H, H-2′ and H-2″); MS: FAB>0 (matrix GT) m/z 437 (M+H)+, 3325 (S)+; FAB<0 (matrix GT) m/z 435 (M−H)−, 111 (B)−; Anal. Calcd for C23H20N2O7: C, 63.30; H, 4.62; N, 6.42. Found: C, 62.98; H, 4.79; N, 6.40.

Provenance & Evidence