反应详情

Aqueous 1M NaOH (12.4 ml, 0.0124 mole) is added to 0° C. solution of 5-[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2(3H)-thione (2.0 g, 0.0062 mole) in methanol (20 ml). This is followed by addition of 2-bromoacetic acid (0.95 g, 0.0068 mole) in one portion. The resulting mixture is allowed to stir four hours with periodic warming. The solution is concentrated in vacuo and the residue is partitioned between ether and water. The layers are separated and the aqueous phase is made acidic with aqueous 6M HCl. The aqueous layer is extracted with 1:1 ethyl acetate/ether (2×). The combined organic layers are washed with saturated aqueous NaCl, and dried over MgSO4. Filtration and concentration in vacuo provides a solid which is recrystallized from ethyl acetate/hexane to give 1.6 g (2.4 g theor., 68%) of [[5-[3,5-bis(1,1-dimethyl-ethyl)-4-hydroxyphenyl]-1,3,4-thiadiazole-2-yl[thio]acetic acid, mp 187.5° C.

1. concentrationThe solution is concentrated in vacuo
2. customthe residue is partitioned between ether and water
3. customThe layers are separated
4. extractionThe aqueous layer is extracted with 1:1 ethyl acetate/ether (2×)
5. washThe combined organic layers are washed with saturated aqueous NaCl
6. dry with materialdried over MgSO4
7. filtrationFiltration and concentration in vacuo
8. customprovides a solid which
9. customis recrystallized from ethyl acetate/hexane