C07D501/00—Heterocyclic compounds containing 5-thia-1-azabicyclo [4.2.0] octane ring systems, i.e. compounds containing a ring system of the formula:, e.g. cephalosporins; Such ring systems being further condensed, e.g. 2,3-condensed with an oxygen-, nitrogen- or sulfur-containing hetero ring
C07D501/14—Compounds having a nitrogen atom directly attached in position 7
C07D501/16—Compounds having a nitrogen atom directly attached in position 7 with a double bond between positions 2 and 3
C07D501/18—7-Aminocephalosporanic or substituted 7-aminocephalosporanic acids