natural product fundamental parent cepham (6R)-5-thia-1-azabicyclo[4.2.0]octan-8-one 143.040 143.20780 An organic heterobicyclic compound that consists of (6R)-5-thia-1-azabicyclo[4.2.0]octane bearing an 8-keto substituent. The parent of the class of cephams. C6H9NOS CHEBI:35993 InChI=1S/C6H9NOS/c8-5-4-6-7(5)2-1-3-9-6/h6H,1-4H2/t6-/m1/s1 QHTOIDKCEPKVCM-ZCFIWIBFSA-N Reaxys:13265235 [H][C@@]12CC(=O)N1CCCS2 cepham chebi_ontology cephams saturated organic heterobicyclic parent