CAS 2689-68-1 appears in our catalog under these names: Methyl 4-oxotetrahydrothiophene-3-carboxylate, 98%, Tetrahydro-4-oxo-3-thiophenecarboxylic Acid Methyl Ester, Methyl 4-oxotetrahydrothiophene-3-carboxylate, technical , Methyl 4-oxotetrahydrothiophene-3-carboxylate, 95%, 95%, Methyl 4-Oxotetrahydrothiophene-3-carboxylate, 95%. Offered by: Combi-blocks, TRC, Thermo Scientific, Chemat, Fluorochem. Available pack sizes: 1g, 10g, 25g, 5g, 100g, 500mg, 100mg, 250mg.