| 摘要 |
The present invention relates to hitherto unknown esters of the below formula I, to salts of the esters of formula I with pharmaceutically acceptable acids, to methods for producing said new compounds, to pharmaceutical compositions containing said new compounds, and to methods of treating patients suffering from infectious diseases using said new compounds. The compounds of the invention, which are valuable in the human and veterinary practice, have the formula I <IMAGE> I in which R1 and R2 represent the same or different substituents, and each represents hydrogen or lower alkyl; A represents a carbon chain having from 5 to 8 carbon atoms, in which optionally an oxygen or a sulphur atom can be substituted for a methylene group; or the grouping <IMAGE> represents a bicyclic system containing from 5 to 10 carbon atoms, or a bicyclic system containing from 4 to 9 carbon atoms, in which optionally an oxygen or a sulphur atom is substituted for a methylene group; or the grouping <IMAGE> represent a spirocyclic system containing from 7 to 10 carbon atoms; R3 represents hydrogen or lower alkyl, halogen substituted lower alkyl, and unsubstituted and substituted aryl and aralkyl. The esters of the present invention are absorbed efficiently when given orally and are non-toxic when given parenterally. After the absorption the esters are converted to the corresponding penicillanic acids by enzymatic hydrolysis. Furthermore, these esters are chemically more stable then the corresponding free acids. |
