反应详情

A suspension of 1.65 g of 7β-amino-3-methoxy-3-cephem-4-carboxylic acid diphenylmethyl ester and 2 ml of anisole is mixed with 20 ml of pre-cooled trifluoroacetic acid and stirred for 15 minutes in an ice bath. It is diluted with 100 ml of cold toluene and the reaction mixture is evaporated under reduced pressure. The dark brown residue is dried under a high vacuum and stirred with diethyl ether; the precipitate is filtered off, washed with acetone and diethyl ether and dried. The salt, thus obtainable, of 7β-amino-3-methoxy-3-cephem-4-carboxylic acid and of trifluoroacetic acid is dissolved in 10 ml of water; the aqueous solution is twice washed with 10 ml of ethyl acetate at a time and brought to a pH of 4.5 by adding a 10% strength solution of triethylamine in methanol. The mixture is diluted with 10 ml of acetone and stirred for one hour at 0° C. The precipitate is filtered off, washed with a 1:2 mixture of acetone and diethyl ether and dried in a high vacuum and yields 7β-amino-3-methoxy-3-cephem-4-carboxylic acid in the form of the internal salt, thin layer chromatogram (silica gel): Rf~0.16 (system: n-butanol/acetic acid/water, 67:10:23); ultraviolet absorption spectrum (in 0.1 N hydrochloric acid): λmax =261 mμ (ε=5,400).

1. customthe reaction mixture is evaporated under reduced pressure
2. customThe dark brown residue is dried under a high vacuum
3. stirringstirred with diethyl ether
4. filtrationthe precipitate is filtered off
5. washwashed with acetone and diethyl ether
6. customdried
7. dissolutionThe salt, thus obtainable, of 7β-amino-3-methoxy-3-cephem-4-carboxylic acid and of trifluoroacetic acid is dissolved in 10 ml of water
8. washthe aqueous solution is twice washed with 10 ml of ethyl acetate at a time
9. additionby adding a 10% strength solution of triethylamine in methanol
10. additionThe mixture is diluted with 10 ml of acetone
11. stirringstirred for one hour at 0° C
12. filtrationThe precipitate is filtered off
13. washwashed with a 1:2 mixture of acetone and diethyl ether
14. customdried in a high vacuum