7-hydroxyheptan-2-one

1-but-3-enylpyrrolidine-2,5-dione

4-(四氢吡喃-2-基氧基)-1-丁烯

but-3-enyl 2-cyclopropylacetate

3,4-bis(but-3-enoxy)cyclobut-3-ene-1,2-dione