Ethanol → 1-(3-O-Benzyl-2-deoxypentofuranosyl)-4-hydroxy-5-(trifluoromethyl)pyrimidin-2(1H)-one

Participants

Reaction Conditions

Reaction Steps

To a stirred mixture of 3.5 g (0.01 mole) of methyl 3-O-benzyl-5-O-(t-butyldimethylsilyl)-2-deoxyribofuranoside and 3.4 g (0.01 mole) of Bis-(trimethylsilyl-5-trifluoromethyluracil in 30 ml of methylene chloride at <5° C. was added a solution of 2.9 g (0.011 mole) of stannic chloride in 5 ml of methylene chloride at ca. 0.25 ml/min. The clear yellow solution was stirred for an additional one and one-half hours at 5° C. during which time the color darkened and a fine precipitate formed. Anhydrous ethanol (11 ml) was then added to the mixture. After warming to ambient temperature, the mixture was filtered removing only a small amount of a solid material. The solvent was then removed under vacuum. The dark residual oil was triturated (3×50 ml) with hexane. The residue was taken up in 100 ml of ethyl acetate, washed with 100 ml of cold saturated sodium bicarbonate solution forming an emulsion. This was vacuum filtered and the filtrate layers separated. The organic phase was washed (2×100 ml) with DI water, dried (Na2SO4), filtered, and the solvent removed under vacuum affording 1.0 g of a thick yellow oil. This material was chromatographed on 75 cc of silica gel eluting with ethyl acetate/hexane (1:1). From early eluting fractions, 150 mg (0.39 mmole, 3.9%) of crude beta-anomer of the title product was obtained with 200 mg (0.52 mmole, 5.2%) of the alpha-anomer being found in later eluting fractions. The products were identified by thin layer chromatography and 1H NMR analysis.

Provenance & Evidence