penams Clavam-2-carboxylate 157.038 157.12410 C6H7NO4 CHEBI:81027 InChI=1S/C6H7NO4/c8-4-1-5-7(4)2-3(11-5)6(9)10/h3,5H,1-2H2,(H,9,10)/t3-,5+/m1/s1 KEGG:C17358 NMPWOLAIBCYZEP-WUJLRWPWSA-N OC(=O)[C@H]1CN2[C@H](CC2=O)O1 chebi_ontology