Piperidine → 5-[2-(3,5-Di-tert-butyl-4-hydroxy-phenyl)-vinyl]-2,4-dihydro-[1,2,4]triazole-3-thione

Participants

Reaction Steps

A solution of 2-(5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)acetic acid (prepared by the method described in Aust. J. Chem., 1979, 32, 161-5, Nowel W. Jacobsen, Bruce L. McCarthy, Stephanie Smith) (3.3 g, 0.021 mole) and 3,5-bis(1,1-dimethylethyl)-4-hydroxybenzaldehyde (4.9 g, 0.021 mole) in a 2:1 mixture of toluene/pyridine (300 ml) is treated with piperidine (0.021 mole). The resulting mixture is stirred at reflux for 48 hours. The mixture is concentrated in vacuo and the residue dissolved in ether, the product is extracted from the organic phase with aqueous 1M NaOH. The combined aqueous layers are made acidic by treatment with aqueous 2M HCl, and the product extracted with a 1:1 mixture of ethyl acetate/ether. The organic layer is washed with saturated aqueous NaCl and dried over MgSO4. Filtration and concentration gives a solid which is triturated in hot isopropyl ether and filtered to provide 2.3 g (6.9 g theor., 33%) of desired (E)-2,4-dihydro-5-[2-[4-hydroxy-3,5-bis(1,1-dimethylethyl)phenyl]ethenyl]-3H-1,2,4-triazole-3-thione, mp 243° C.

Provenance & Evidence