反应详情

To a cold (ice/water bath) solution of (2R,3R)-2-((benzyloxy)methyl)-3-(tert-butyldimethylsiloxy)butan-1-ol (4) (W.-H. Ham et al. J. Org. Chem. 2000, 65, 8372-8374) 1.5 g, 4.6 mmol), 3-benzoylthymine (1.5 g, 6.5 mmol) and triphenylphosphine (1.71 g, 6.5 mmol) in 50 ml of anhydrous THF was added dropwise via syringe with stirring (1.26 ml, 6.5 mmol) of diisopropylazodicarboxylate. The reaction was removed from the bath and stirred at room temperature for 2 hrs and then concentrated. The reaction was diluted with ether (50 ml) and hexane (50 ml) to precipitate some of triphenylphosphine oxide and the DIPADC by-product. The solids were filtered off and the filtrate concentrated. The resultant crude product, which still contained some Ph3PO, was chromatographed on silica eluting with 20% ethyl acetate in hexane. Concentration of the pure product fractions afforded 2.0 g (81%) of 5 as a colorless viscous srup. 1H NMR (CDCl3): δ 7.85 (d, J=8.4 Hz, 2H), 7.58 (t, J=7.5 Hz, 1H), 7.42 (t, J=7.8 Hz, 2H), 7.35-7.25 (m, 5H), 7.06 (d, J=1.2 Hz, 1H), 4.42 (s, 2H), 3.98 (m, 2H), 3.61 (m, 1H), 3.46 (d, J=5.7 Hz, 2H), 2.08 (m, 1H), 1.83 (s, 3H), 1.16 (d, J=6.6 Hz, 3H), 0.84 (s, 9H), 0.02 (s, 3H), 0.00 (s, 3H).

1. customThe reaction was removed from the bath
2. concentrationconcentrated
3. additionThe reaction was diluted with ether (50 ml) and hexane (50 ml)
4. customto precipitate some of triphenylphosphine oxide
5. filtrationThe solids were filtered off
6. concentrationthe filtrate concentrated
7. customwas chromatographed on silica eluting with 20% ethyl acetate in hexane