CEPHALOSPORIN DERIVATIVE

摘要

A cephalosporin derivative represented by general formula (I) or a salt thereof, wherein R<1> represents hydrogen, lower alkenyl, lower alkynyl, cycloalkyl, hydroxyl-protecting group, or (un)substituted lower alkyl; R<2> represents hydrogen, ester residue, or negative charge; R<3> represents either (1) a group represented by general formula (a), wherein R<4> and R<5> represent each independently lower alkoxy or (un)substituted amino, or R<4> and R<5> may be combined together with the neighboring tetrahydropyridazine ring to form an (un)substituted fused 5- or 6-membered ring, or (2) a group represented by general formula (b) or (c), wherein R<6> and R<7> represent each independently hydrogen, halogen, amino, azido, carbamoyl, lower alkyl which may be substituted by amino, azido, carbamoyl or halogen, carbamoyl, or (un)substituted 5- or 6-membered heterocyclic group (provided the nitrogen atom of the heterocycle may be substituted to form a quaternary amine); X represents methine (-CH=) or nitrogen; and ring A represents a 4- to 5-membered nitrogenous heterocycle which may contain oxygen.