tert-butyl 2-(bromomethyl)-1,3-oxazole-4-carboxylate

tert-butyl 3-amino-3-phenylprop-2-enoate

ditert-butyl 2-hydroxybut-2-enedioate

tert-butyl 4-methylpent-2-enoate

tert-butyl 3-oxohept-6-enoate