Reaction Steps
The title compound was prepared according to general method C. (S)-2-Chloro-N-[2-(methylmethoxy)-1-pyrrolidinyl]adenosine [Knutsen, L. J. S., Lau, J., Sheardown, M. J., Thomsen, C.; Bioorganic and Medicinal Chemistry Letters, 1993, 3, 2661-2666](0.35 g, 0.8 mmol) was dissolved in acetonitrile (5 ml) and cooled on an ice-water bath. Under a nitrogen atmosphere, thionyl chloride (0.34 g, 0.2 ml, 2.4 mmol) (see Borchardt, R. T., Huber, J. A. and Wu, Y. S., Journal of Organic Chemistry, 1976, 41, 565-567) was added and a precipitate appeared which dissolved over the following 15 min. Pyridine (0.13 ml, 0.13 g, 1.6 mmol) was introduced gradually, the reaction mixture became yellow in colour and was allowed to reach room temperature gradually. After stirring the mixture overnight, ice was added and the reaction mixture was neutralised to pH 7 with aqueous sodium bicarbonate prior to extraction with ethyl acetate (2×10 ml). The combined extracts were dried (MgSO4) and evaporated to provide the intermediate 2,3-O-sulphinyl derivative (0.35 g), to which was added methanol (5 ml), water (1 ml) and 25% aqueous ammonia solution (0.25 ml) and this mixture was stirred for 16 h. The solution was evaporated in vacuo, and the resultant residue was purified by flash chromatography on silica gel eluting with a mixture of dichloromethane and 10% ammonia in ethanol (17:3), to provide the title (S)-2,5'-dichloro-5'-deoxy-N-[2-(methylmethoxy)-1-pyrrolidinyl]adenosine (0.12 g, 34%) as a foam, 1H-NMR (400 MHz, DMSO-d6) δ1.50-1.60 (1H, br, pyrrolidine C--H), 1.78 (2H, br q, pyrrolidine C--H), 1.92-2.03 (1H, br, pyrrolidine C--H), 3.85, 3.95 (2H, ABX, H-5'a and H-5'b), 4.09 (1H, br dd, H-4'), 4.17 (1H, dd, H-3'), 4.67 (1H, dd, H-2'), 5.49, 5.62 (2H, 2d, 2'- and 3'-OH), 5.87 (1H, d, H-1'), 8.38 (1H, s, H-8), 9.34 (1H, br s, --NH). HPLC retention time 9.65 min. (gradient elution over 30 min.; 20-80% acetonitrile/0.1% TFA in water, 99% purity at 250 nm). C16H22Cl2N6O4.0.25 H2O requires C, 43.9; H, 5.2; N, 19.2. Found: C, 43.7; H, 5.4; N, 19.4%.
