Trisodium citrate → sodium (6R,7R)-7-[[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-8-oxo-3-[(2R)-oxolan-2-yl]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate

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Reaction Steps

Aluminium chloride (740 mg, 5.55 mmol) was added to anisole (32 ml) and dry dichloromethane (15 ml) at -20° C. and stirred for 15 min. The temperature of the cooling bath was then lowered to -40° C. before addition of a solution of 4-methoxybenzyl (6R,7R)-7-[2-(2-aminothiazol-4-yl)-2-(Z)-methoxyiminoacetamido]-3-[(R)-tetrahydrofuran-2-yl]ceph-3-em-4-carboxylate (1.06 g, 1.85 mmol) in dichloromethane (10 ml). After 1 min., the solution was treated with trisodium citrate (0.5M, 54 ml) and then vigorously stirred for 10 min. at room temperature. The aqueous phase was separated, washed with dichloromethane (×2) and concentrated in vacuo. The residue was chromatographed on HP20SS eluting with water, then 1% THF in water. Fractions containing the product, (h.p.l.c. analysis), were combined and freeze-dried to give the title compound (560 mg, 64%); νmax (KBr) 3399, 1762, 1669, 1603, 1529, 1038 cm-1 ; δH (d6 -DMSO, 250 MHz) 1.50-1.91 (4H, m), 3.25 and 3.38 (2H, ABq, J 16.8 Hz), 3.60-3.82 (2H, m), 3.84 (3H, s), 4.96 (1H, d, J 4.7 Hz), 5.20 (1H, dd, J 8.6, 6.0 Hz), 5.48 (1H, dd, J 8.1, 4.7 Hz), 6.76 (1H, s), 7.23 (2H, br. s, exch.), 9.50 (1H, d, J 8.1 Hz, exch.). [Mass spectrum: +ve ion (thioglycerol) MH+ (476), MNa+ (498)].

Provenance & Evidence