反应详情

To a suspension of 181 g. of 7-amino-3-methyl-3-cephem-4-carboxylic acid (7-ADCA) in 1700 ml. of water, 142 g. of NaHCO3 were slowly added followed by a solution of 186 g. of N-carbethoxyphthalimide in 1 liter of acetone added dropwise over a 30 minute period. After stirring for 3 hrs. the solution was cooled in an ice-water bath and acidified to pH 2.1 by addition of 600 ml. of 42.5% of H3PO4. The resulting precipitate was filtered, washed with water, and vacuum dried to give 227 g. of a mixture of the starting material and the desired phthalimido compound. The mixture was separated by extraction with warm acetone and ethyl acetate, recovering 105 g. of 7-ADCA. The yield of the phthalimido compound was 114 g. A sample (1 g.) of product was crystallized from acetone (15 ml.); colorless crystals, m.p. 223°-225°; [α]D + 428.02° (MeCN); ir (nujol) 1810, 1785, 1740 and 1710 cm-1 ; nmr (CDCl3) δ 2.38 (s, 3, CH3), 3.0 and 3.75 (ABq, 2, J=14 Hz), 5.13 (d, 1, J=4.5 Hz), 5.71 (d, 1, J=4.5 Hz), and 7.82 (m, 4, ArH).

1. additionTo a suspension of 181 g
2. temperaturethe solution was cooled in an ice-water bath
3. additionacidified to pH 2.1 by addition of 600 ml
4. filtrationThe resulting precipitate was filtered
5. washwashed with water, and vacuum
6. customdried
7. customto give 227 g
8. additionof a mixture of the starting material
9. customThe mixture was separated by extraction with warm acetone and ethyl acetate
10. customrecovering 105 g
11. customA sample (1 g.) of product was crystallized from acetone (15 ml.)
12. custom[α]D + 428.02° (MeCN)