CAS 1644287-27-3 appears in our catalog under these names: 6-Ketopemetrexed, Pemetrexed 6-Oxo Diacid Impurity, Pemetrexed Impurity 18, Pemetrexed Impurity 7 (Mixture of Diastereomers). Offered by: Mikromol, Chemat Brand, Hubei YoungXin. Available pack sizes: 25mg, on request, 10mg, 50mg, 100mg, 200mg.