反应详情

To a solution of 9-(2,3,5-tri-O-benzyl-β-D-arabinofuranosyl)adenine (5, 15.0 g., 27.1 mmoles) in a mixture of 500 ml. tetrahydrofuran and 1 l. of 48% fluoboric acid at -10° in a 4-l. beaker equipped with a mechanical stirrer was added dropwise in 20 minutes a saturated aqueous solution of sodium nitrite (7.5 g., 108 mmoles). The addition of sodium nitrite was repeated three times after which none of the 2-aminoadenine remained (tlc). The fluorboric acid was neutralized to pH 6 with 505% sodium hydroxide keeping the temperature between -40° and 0°. The solution was extracted four times with chloroform (300 ml., 250 ml., and two 200-ml. portions). The chloroform extract was washed with saturated sodium chloride solution and then dried over magnesium sulfate before it was evaporated to dryness in vacuo. The residual oil was dissolved in a liter of ethanolic ammonia (saturated at 0°), and the solution was allowed to stand for 4 days at 4° before it was evaporated to dryness. The residue was recrystallized from ethanol; yield 5.5 g. Additional material was recovered from the filtrate by recrystallization and the final filtrate was evaporated to dryness, diluted with 50 ml. of 1 N hydrochloric acid, stirred on a steam bath for 30 minutes, cooled, and the aqueous portion decanted. A chloroform solution of the residue was washed with saturated sodium bicarbonate, then water, and dried over magnesium sulfate before evaporation in vacuo. The residue was recrystallized from ethanol; total yield of 6, 7.2 g. (48%); m.p. 155°-157°. This material was essentially homogeneous according to tlc (19:1) and hplc [2 aqueous pentanesulfonic acid (0.005 M):3 acetonitrile-3% acetic acid].

1. customat -10°
2. custombeaker equipped with a mechanical stirrer
3. customthe temperature between -40° and 0°
4. extractionThe solution was extracted four times with chloroform (300 ml., 250 ml., and two 200-ml. portions)
5. extractionThe chloroform extract
6. washwas washed with saturated sodium chloride solution
7. dry with materialdried over magnesium sulfate before it
8. customwas evaporated to dryness in vacuo
9. dissolutionThe residual oil was dissolved in a liter of ethanolic ammonia (saturated at 0°)
10. customwas evaporated to dryness
11. customThe residue was recrystallized from ethanol
12. customAdditional material was recovered from the filtrate by recrystallization
13. customthe final filtrate was evaporated to dryness
14. additiondiluted with 50 ml
15. temperaturecooled
16. customthe aqueous portion decanted
17. washA chloroform solution of the residue was washed with saturated sodium bicarbonate
18. dry with materialwater, and dried over magnesium sulfate before evaporation in vacuo
19. customThe residue was recrystallized from ethanol