The compounds according to the invention correspond to the formula: ##STR1## in which: The COOA group at the 4 position is an acid radical, or an alkaline or alkaline-earth salt, or an amino acid or amine salt, for example triethylamine or ethanolamines, or an easily hydrolyzable or metabolically labile and pharmaceutically acceptable ester radical. X denotes an oxygen atom or a sulfur atom n is zero or 1 R.sub.1 and R.sub.2 each denote independently hydrogen or a lower alkyl group, preferably a methyl group, or R.sub.1 and R.sub.2 taken together with the carbon atom to which they are linked form a cyclobutyl or cyclopentyl nucleus. B is the residue of a primary or secondary amine.
该发明涉及的化合物对应于以下公式:##STR1## 其中:4位置的COOA基团是酸基、碱性或碱土
金属盐、
氨基酸或胺盐,例如
三乙胺或
乙醇胺,或易于
水解或代谢不稳定且药学上可接受的酯基团。X表示氧原子或
硫原子,n为零或1,R1和R2各自独立地表示氢或较低的烷基,优选为甲基,或R1和R2与它们连接的碳原子一起形成
环丁基或环戊基核。B是一次或二次胺的残基。