4H-Pyran-2-carboxylic acid, 5-hydroxy-6-((4-methyl-1-piperazinyl)methyl)-4-oxo-, ethyl ester 66556-16-9 Ethyl 5-hydroxy-6-((4-methyl-1-piperazinyl)methyl)-4-oxo-4H-pyran-2-carboxylate