反应详情

A stirred suspension of 2-[4-(4-chlorophenyl)phenyl]-5,5-dimethyl-1,3-dioxolan-4-one (100.0 g.), 5% w/w palladium on carbon (10 g.) in a mixture of ethanol (500 ml.) and water (1000 ml.) was cooled to 10° to 15° C. and treated with carbon dioxide gas. The temperature and gas flow were maintained during the addition of a solution of sodium borohydride (63.0 g.) in water (250 ml.) during 1 hour. After 5 hours at 15° to 20° C. the pH of the reaction mixture was adjusted to pH 12 with 47% w/w sodium hydroxide solution and diluted with ethanol (1000 ml.). The residue was separated by filtration and washed successively with ethanol (2×250 ml.) and water (2×250 ml.). The combined filtrate and washings were evaporated to about half volume and the pH adjusted to 3 with 34% w/w hydrochloric acid. The solid which formed was recrystallised twice from toluene to give 2-[4-(4-chlorophenyl)benzyloxy]-2-methylpropionic acid, (m.p. 154°-155° C.) in 42% yield.

1. temperaturewas cooled to 10° to 15° C.
2. customThe residue was separated by filtration
3. washwashed successively with ethanol (2×250 ml.) and water (2×250 ml.)
4. customThe combined filtrate and washings were evaporated to about half volume
5. customThe solid which formed
6. customwas recrystallised twice from toluene