5-methoxy-4-oxopyran-2-carboxylic acid

5-苄氧基-4-氧代-4H-吡喃-2-羧酸

(5-acetyloxy-4-oxopyran-2-yl)methyl acetate

(5-hydroxy-4-oxopyran-2-yl)methyl N-phenylcarbamate

5-hydroxy-2-(trityloxymethyl)pyran-4-one