2689-68-1 3-Thiophenecarboxylic acid, tetrahydro-4-oxo-, methyl ester 4-Carbomethoxy-3-thiophanone 99328-39-9 EINECS 220-256-9 Methyl tetrahydro-4-oxo-3-thenoate Methyl tetrahydro-4-oxo-3-thiophenecarboxylate NSC 127560