a column of Dowex 50-W (acid form, 70 ml) by washing initially with water until free of uv-absorbing material, then eluting stepwise with 0.1 M and 0.3 M pyridinum formate buffer (pH 4.5). The initial eluates (2.8 1.) were discarded; 3.1 1. of the successive eluates was evaporated to dryness. The residue was dissolved in 25 ml of water and passed through the column of Diaion (chloride form, 10 ml), followed by washing with water. The combined effluent and washings were concentrated to dryness. The residue was triturated with EtOH and crystallization took place.Colorless needles were obtained (0.61 g, 54.55%): mp over 260°; kmax (e X 10"3) H20, 230 (9.1), 269 nm (11.2); 1N HC1, 230 (10.1), 269 nm (12.0); nmr ( ) 8.37 (d, 1 H, C6-H), 5.62 (d, 1 H, C2rH).Anal. (C9HUN304FC1) C, , N. 5-Iodo-ara-C (VIII). lib (100 mg) was dissolved in 15 ml of 1 M triethylammonium bicarbonate (pH 7.5) and heated at 50°for 40 min. The reaction mixture was evaporated and the residue was dissolved in 10 ml of water to adjust the pH to 2.0 with 0.1 TV HC1. The product was isolated on a column of Dowex 50-W (ammonium form, 4 ml) by washing with water until free of uv-absorbing material. The effluent was concentrated to dryness, and the residue was crystallized from EtOH: yield, 57 mg (60.5%); mp 205°dec,13 kmax H20, 223, 295 nm; 1 N HC1, 310 nm.2',6-Anhydro-6-hydroxy-ara-C (IX). VIII (3.0 g) was dissolved in a mixture of 70 ml of DM SO and 25 ml of ferf-BuOH. To this solution was added a mixture of 20 ml of 1 N sodium ferf-butoxide and 40 ml of DMSO under stirring at 60°and heating was continued for 2 hr. The pH of the reaction mixture was adjusted to 9.0 with Dowex 50-W (ammonium form, 40 ml), and the resin was filtered off. The filtrate was concentrated to 100 ml and passed through the column of Dowex 50-W (acid form, 140 ml) to absorb a cyclized product. Isolation was achieved by washing initially with water until free of uv-absorbing material, then eluting with 5% ammonium hydroxide (1.2 1.). The eluates were concentrated to a small volume to give pure crystals. Recrystallization from minimum amount of water afforded an analytical sample: yield, 0.986 g (50.30%); mp 276°dec; Xmax (e X 10"3) pH 7, 222 (11.14), 261.5 nm (14.1);pH 1,266 (23.3); R{(A) 0.12, (B) 0.32. Anal. ( , ,, , ,) C, , N.The combined effluent was concentrated to dryness, and the residue was repeatedly washed with ether and dissolved in a small amount of water to give white prisms: yield, 730 mg; mp 235-237°d ec; \max H20, H+, OH", 275 nm. This compound is not yet characterized.
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