反应详情

A solution of 20.8 g (2.1×177 mmol) of potassium hydroxide in 100 mL of water is added to a solution of 57.8 g (177 mmol) of 2,2-dimethylpropanoic acid, 2,3,5-trimethyl-4-(phenylmethoxy)phenyl ester (Example B) in 300 mL of methanol. The solution is stirred at reflux for 6 hours, then permitted to stir at ambient temperature for another 8 hours. The solvent is removed on a rotary evaporator and the residual aqueous solution (dark brown) is diluted with 100 mL of water and acidified with excess 6N hydrochloric acid solution (40 mL). The product is isolated with diethyl ether and the diethyl ether solution is washed with 2×100 mL saturated (10%) sodium bicarbonate solution, brine, dried (magnesium sulfate) and evaporated leaving 48.4 g of crude product as a light brown solid. Chromatography on a 6.5 cm column containing 350 g of silica gel prepared in toluene and elution with 95% toluene:5% ethyl acetate affords 30.6 g of the title compound; mp 101°-103° C.

1. temperatureat reflux for 6 hours
2. stirringto stir at ambient temperature for another 8 hours
3. customThe solvent is removed on a rotary evaporator
4. additionthe residual aqueous solution (dark brown) is diluted with 100 mL of water
5. customThe product is isolated with diethyl ether
6. washthe diethyl ether solution is washed with 2×100 mL saturated (10%) sodium bicarbonate solution, brine
7. dry with materialdried (magnesium sulfate)
8. customevaporated
9. customleaving 48.4 g of crude product as a light brown solid
10. additionChromatography on a 6.5 cm column containing 350 g of silica gel
11. washelution with 95% toluene