Three positional analogues (4-, 5-, and 7-) of benzothienylglycine and (N-acetylindolinyl)-5-glycine were prepared and coupled to 7-aminodeacetoxycephalosporanic acid (7-ADCA) to give the cephalosporins 17a-c. In addition two isomeric (2,3-b and 3,2-b) thienothiopheneglycines were synthesized and coupled to 7-ADCA to yield cephalosporins 30d and 30e. In vitro testing of these new cephalosporins indicates good activity against Gram-positive bacteria. Against Streptococcus pneumoniae infections compound 25 displayed better mouse protection (both orally and subcutaneously) than cephalexin.
A structure-activity relationship study of a number of orally absorbed cephalosporins together with their syntheses is described. These new cephalosporins are benzothienyl- and naphthylglycine derivatives of 7-aminodeacetoxycephalosporanic acid. Several different synthetic methods for the glycine side chains, their protection, and the final acylations are reported. Several of these analogues were more active than cephalexin both in vitro and in vivo against commonly encountered Gram-positive bacteria. (R)-7-(3-Benzothienylglycylamido)-3-methyl-3-cephem-4-carboxylic acid (1R) has emerged as a potent antibacterial agent and is currently undergoing preclinical evaluation.
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