Sodium Iodide → HCID 10435134, compound

Participants

Reaction Steps

A mixture of dry 5,6-dichlorobenzimidazole-2-thione (3, 2.19 g 10 mmole), hexamethyldisilazane (4 ml) and (NH4)2SO4 (0.1 g) was heated at reflux temperature with stirring for 15 hr under anhydrous conditions. The clear brown reaction mixture was fractionated to remove unreacted HMDS under reduced pressure (water aspirator) to afford the disilylated compound. The silylated compound was mixed with 1-bromo-2,3,5-tri-O-acetyl-D-ribofuranose (from 3.5 g (11 mmole) of tetraacetylsugar) and sodium iodide (0.05 g). The mixture was then fused at 110° C. (oil bath temperature) with stirring for 45 minutes under reduced pressure. The reaction mixture which had been cooled to room temperature was dissolved in CHCl3. The CHCl3 solution was washed with a cold saturated aqueous sodium bicarbonate solution (100 ml×4) and then cold water (100 ml×4). The CHCl3 phase was dried over Na2SO4 and evaporated on a water bath (40° C.) to dryness to yield a syrup [5,6-dichloro-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl) benzimidazole-2-thione]. The syrup was dissolved in methanolic ammonia (methanol saturated with ammonia at 0° C., 100 ml) and allowed to stand at room temperature for 24 hours. After the methanolic ammonia had been removed at room temperature, a syrup remained which was triturated with cold water (30 ml). The solid material (2.548 g) which separated was collected by filtration and was applied to a flash column chromatography on silica gel with CH2Cl2 -MeOH (15:1) as eluant. Fractions were collected (25 ml each), and fractions containing the desired compound were combined and evaporated to obtain 53 which was crystallized from aq. EtOH. Overall yield 2.0 g, 57.0%, mp 241° C.

Provenance & Evidence