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0 °C

4-Methoxybenzyl (6R,7R)-7-amino-3-[(R)-tetrahydrofuran-2-yl)ceph-3-em-4-carboxylate (136mg, 0.35mmol) [See example 6] in THF (10ml) was stirred in an ice bath with dicyclohexylcarbodiimide (108mg, 0.52mmol) then (R)-2-t-butoxycarbonylamino-2-(4-hydroxyphenyl)acetic acid (139mg, 0.52mmol) in THF (3ml) was added dropwise over 2 min. The mixture was stirred at 0° C. for 30 min then at room temperature for 30 min. It was filtered and evaporated and the residue chromatographed on silica gel eluting with ethyl acetate/hexane mixtures. The title compound was obtained as a white solid (212mg, 95%); δH (CDCl3) 1.10-2.0 (4H,m), 1.42 (9H,s), 3.18 and 3.43 (2H,ABq, J 17Hz), 3.80 (3H,s), 3.77-3.88 (2H,m), 4.89 (1H,d, J 5Hz), 5.10 (1H,t, J 7Hz), 5.11 (1H,d, J 5Hz), 5.19 (2H, s), 5.65 (1H,d, J 5Hz exch), 5.69 (1H,dd, J 4,9Hz), 6.72 (2H,d, J 8Hz), 6.81 (1H,d, J 9Hz exch), 6.88 (2H,d, J 9Hz), 7.10 (2H,d, J 8Hz) and 7.33 (2H,d,J 9Hz). (Mass spectrum: +ve ion (3-nitrobenzyl alcohol, sodium acetate) MNa+ (938)].

1. waitat room temperature for 30 min
2. filtrationIt was filtered
3. customevaporated
4. customthe residue chromatographed on silica gel eluting with ethyl acetate/hexane mixtures