4-Amino-4-deoxy-N(10)-methylpteroyl-(6-chloro-5-oxo)norleucine 83160-47-8 Chloromethylketone methotrexate L-Norleucine, 6-chloro-N-(4-(((2,4-diamino-6-pteridinyl)methyl)methylamino)benzoyl)-5-oxo- Methotrexate chloromethylketone analog