Carbonyl diimidazole (0.7 g, 0.004 mole) is added in one portion to a stirred 0° C. solution of 3,5-bis(1,1-dimethylethyl)-4-hydroxy-cinnamic acid hydrazide (1.0 g, 0.003 mole) and triethylamine (0.4 g, 0.004 mole) in tetrahydrofuran (12 ml). The mixture is stirred at 0° C. for 15 minutes and then allowed to warm to room temperature and stir 45 minutes. The solution is concentrated and the residue dissolved in ether (50 ml) and washed with aqueous 2M HCl. The product is extracted from the organic layer by treatment with aqueous 1M NaOH (20 ml). The aqueous extract is made acidic by treatment with cold aqueous 2M HCl and the product is extracted with ether. The organic layer is washed with saturated aqueous NaCl and dried over MgSO4. Filtration and concentration provided a solid which was recrystallized from ethyl acetate/hexane to give 1.0 g (1.1 g theor., 94%) of 5-[2-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]ethenyl]-1,3,4-oxadiazole-2(3H)-one, mp >260° C.
