反应详情

A solution of 1.95 g (4.5 mmole) of 4-(3-hydroxyoctyl)-2,5-dioxo-1,3,4-thiadiazoline-3-heptanoic acid tert-butyl ester (6) in 10 ml of trifluoroacetic acid was kept at 0° for 1.5 hr and then evaporated at 0° under vacuum. Benzene (75 ml) was added to the residue and the solution re-evaporated. The remaining oil was stirred with 100 ml of 5% NaHCO3 for 1 hr and extracted with ether, the ether extract then being discarded. The remaining aqueous raffinate was then acidified with HCl and extracted with ether, giving 1.7 g of 4-(3-hydroxyoctyl)-2,5-dioxo-1,3,4-thiadiazoline-3-heptanoic acid (8); Rf =0.26 on silica gel, 1:1 CHCl3 --ether, I2 visualization. Acid 8 was identified by its solubility in 5% NaHCO3.

1. customevaporated at 0° under vacuum
2. additionBenzene (75 ml) was added to the residue
3. customthe solution re-evaporated
4. extractionextracted with ether
5. extractionthe ether extract
6. extractionextracted with ether