Heterocyclyl-imino-acetamido-cephalosporin derivs. - useful as antibacterials and their precursors

摘要

Cephalosporins of formula (I), and their pharmaceutically acceptable salts and bio-precursors are new:- (R1=thiadiazolyl, 2-R6-thiazoyl (R6=opt. protected amino) or haloacetyl. A is CH2 or -C(=N is approx. OR2). R2=H or aliphatic hydrocarbyl opt. substd. by halo, COOH or esterified COOH. R3=H or lower alkyl. R4=H, halo, lower alkyl or OR7. R7=H, lower alkyl or acyl. R5=opt. modified COOH. The dotted line is a single or double bond). R4 is not lower alkyl, when R3 is H; R4 is lower alkyl when R3 is lower alkyl; A is not CH2 unless R1 is haloacetyl; DELTA 3 is present and R4 is H, halo, lower alkyl, or lower alkoxy, when R1 is haloacetyl. When R2=ethyl, isopropyl or allyl, R'6 is amino or non-substd. alkanamido, and R8 is H. (I) where A is -C(=N is approx. Or2) and R1 i heterocyclic are antibacterials for therapeutic or prophylactic treatment of human or animal infections; the syn isomers are the more active. The other (I) are intermediates. The cpd. syn-7- 2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido -3-cephem-- 4-carboxylic acid has sub-cutaneous LD50 >8mg/kg in rats.