4-hydroxybut-2-enyl but-2-ynoate

benzoic acid,but-2-ene-1,4-diol

cis-1,4-bis-(O-trityl)but-2-ene

(2Z)-1,4-二溴-2-丁烯

(Z)-1,4-bis(trimethylsilyloxy)but-2-ene