反应详情

2,2,2-Trichloroethyl chloroformate (3.15 ml, 22 mmole) was added to a suspension of 2,2,2-trichloroethyl 7β-amino-3-methylceph-3-em-4-carboxylate hydrogen p-toluenesulphonate (10.36 g, 20 mmole) in a mixture of dimethylacetamide (25 ml) and acetonitrile (100 ml.) The mixture was stirred at ca. 25° for 30 minutes, the acetonitrile was evaporated and ethyl acetate (80 ml) was added. The solution was washed with saturated sodium hydrogen carbonate solution (80 ml), dried and evaporated to an oil which could not be crystallised. The oil was taken up in chloroform (50 ml), washed with water (3 × 50 ml) and re-evaporated to an orange foam which on trituration with methanol (20 ml) gave the title ester as an off-white solid, λmax. 262 nm (E1cm1% 113.5). Crystallisation from ethanol gave an analytical sample, m.p. 179° to 181.5°, [α]D + 70°, λmax. 262 nm (ε 6,000), νmax (CHBr3) 3410 (NH), 1780 (azetidin-2-one), 1740 and 1520 (NHCO2R) and 1740 cm-1 (CO2R), τ(CDCl3) 3.98 (1H,d,J 9.5 Hz; NH), 4.34 (1H,dd,J 9.5 Hz; C7 -H) 4.91 (1 H,d J 5 Hz; C6 -H), 4.91, 5.08 (2H, AB-q, J 12 Hz; CO2CH2CCl3), 5.17 (2H, s; NHCO2CH2CCl3), 6.34, 6.73 (2H, AB-q, J 18 Hz; C2 -H2), 7.74 (3H,s; C3 -CH3) (Found: C, 30.3; H, 2.4; Cl, 40.2; N, 5.3; S, 6.5. C13H12Cl6N2O5S (521.1) requires C, 30.0; H, 2.3; Cl, 40.8; N, 5.3; S, 6.2%

1. customthe acetonitrile was evaporated
2. additionethyl acetate (80 ml) was added
3. washThe solution was washed with saturated sodium hydrogen carbonate solution (80 ml)
4. customdried
5. customevaporated to an oil which could not
6. custombe crystallised
7. washwashed with water (3 × 50 ml)
8. customre-evaporated to an orange foam which on trituration with methanol (20 ml)