1,3-Cyclopentanedicarboxylic acid, 2-methyl-4,5-dioxo-, diethyl ester 23033-97-8 Diethyl 2-methyl-4,5-dioxo-1,3-cyclopentanecarboxylate Diethyl 4,5-dioxo-2-methyl-1,3-cyclopentanedicarboxylate EINECS 245-390-5