反应详情

A solution of the phosphorane from Example 31(g) (517mg) in dry toluene (100ml) was heated at reflux under dry argon for 8 hours and evaporated. the residue was chromatographed on silica gel eluting with ethyl acetate/hexane mixtures to give two fractions. The less polar fraction contained 4-methoxybenzyl (6R,7R)-3-[(2S,5R)-5-acetoxymethyltetrahydrofuran-2-yl]-7-phenylacetamidoceph-3-em-4-carboxylate, a foam (105mg); vmax (CHCl3) 3410, 1784, 1726 and 1683cm-1 ; δH (CDCl3) 1.53-1.83 (3H, m), 2.09 (3H, s), 2.19-2.36 (1H, m), 3.30 and 3.55 (2H, ABq, J 18.9Hz), 3.60 and 3.69 (2H, ABq, J 16.2Hz), 3.81 (3H, s), 4.01-4.21 (3H, m), 4.90 (1H, d, J 4.8Hz), 4.96 (1H, dd, J 8.3, 6.7Hz), 5.12 and 5.17 (2H, AA'q, J 12.5Hz), 5.81 (1H, dd, J 9.2, 4.8Hz), 5.97 (1H, d, J 9.2Hz), 6.85-6.92 (2H, m), 7.25-7.41 (7H, m). [Mass spectrum: +ve ion (3-nitrobenzyl alcohol, sodium acetate) MH+ (581), MNa+ (603)]. The more polar fraction contained 4-methoxybenzyl (6R,7R)-3-[(2R,5S)-5-acetoxymethyltetrahydrofuran-2-yl]-7-phenylacetamidoceph-3-em-4-carboxylate, a solid (191mg), m.p. 185-187° C. (needles ex ethyl acetate/hexane); vmax (CHCl3) 3407, 1785, 1731 and 1682cm-1 ; δH (CDCl3) 1.53-1.78 (2H, m), 1.90-2.05 (2H, m), 2.08 (3H, s), 3.35 and 3.57 (2H, ABq, J 18.0Hz), 3.61 and 3.69 (2H, ABq, J 16.2Hz), 3.80 (3H, s), 4.01-4.19 (3H, m), 4.91 (1H, d, J 4.8Hz), 5.12-5.27 (3H, m), 5.74 (1H, dd, J 4.8, 9.0Hz), 6.04 (1H, d, J 9.0Hz), 6.85-6.91 (2H, m), 7.25-7.41 (7H, m). [Mass spectrum: +ve ion (3-nitrobenzyl alcohol, sodium acetate) MH+ (581), MNa+ (603)].

1. temperatureat reflux under dry argon for 8 hours
2. customevaporated
3. customthe residue was chromatographed on silica gel eluting with ethyl acetate/hexane
4. customto give two fractions