1-benzyl-2-[(E)-2-butenoyl]-5-spirocyclopentane-pyrazolidin-3-one

S-crotonyl-2-mercaptoethyl 4-methoxycinnamide

1-(1-naphthylmethyl)-2-[(E)-2-butenoyl]-5,5-dibenzyl-pyrazolidin-3-one

(E)-But-2-enoic acid 2-[(1S,4R)-4,7,7-trimethyl-3-oxo-bicyclo[2.2.1]hept-(2E)-ylidenemethyl]-phenyl ester

S-tert-butyl (E)-2-butenethioate