吡喃是六元杂环，非芳香环，由五个碳原子和一个氧原子组成，并含有两个双键。分子式为C5H6O，吡喃有两个异构体，其位置与双键的位置不同。在2H吡喃中，饱和碳处于位置2，而在4H-吡喃中，饱和碳位于位置4。
7,8-Dihydroxy-4-methyl-2H-chromen-2-one
7-Mercapto-4-methyl-2H-chromen-2-one
7-Methoxy-4-methylcoumarin
2-Amino-N-(4-methyl-2-oxo-2H-chromen-7-yl)acetamide
Glycine 7-amido-4-methylcoumarin hydrochloride
Methyl 2-(7-hydroxy-4-methyl-2-oxo-2H-chromen-3-yl)acetate
2-(3,4-Dimethoxyphenyl)-5-hydroxy-6,7-dimethoxy-4H-chromen-4-one
5,6,7-Trihydroxy-2-(4-hydroxyphenyl)-4H-chromen-4-one
5,7-Dihydroxy-2-(4-hydroxy-3-methoxyphenyl)-6-methoxy-4H-chromen-4-one
5,7-Dihydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one
5,6-Dihydroxy-7-methoxy-2-phenyl-4H-chromen-4-one
5-Hydroxy-7-methoxy-2-phenyl-4H-chromen-4-one
5-Hydroxy-2-phenyl-4H-chromen-4-one
2-(3,4-Dimethoxyphenyl)-5,7-dihydroxy-6-methoxy-4H-chromen-4-one
5,7-Dihydroxy-2-(4-hydroxyphenyl)-8-(3-methylbut-2-en-1-yl)-4H-chromen-4-one
5,7-Dihydroxy-6-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one
5,7-Dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one
4-Hydroxy-6-methoxy-2H-chromen-2-one
4-Hydroxy-7-methoxy-2H-chromen-2-one
4-Hydroxy-6-methylcoumarin
6-Fluoro-4-hydroxy-2H-chromen-2-one
6-Bromo-4-hydroxycoumarin
6-Chloro-4-hydroxy-2H-chromen-2-one
7-Fluoro-4-hydroxy-2H-chromen-2-one
7,8-Difluorochroman-4-one
7-Fluoro-2,2-dimethylchroman-4-one
5-Bromo-7-fluorochroman-4-one
7-Fluorochroman-4-one
7-(Diethylamino)-2-oxo-2H-chromene-3-carbohydrazide
7-(Diethylamino)-2H-chromen-2-one
