Sodium Hydroxide → 2-Phenylhexahydro-2,5-methanopentalene-3a-carboxylic acid

Participants

Reaction Steps

Dioxane (1.81) was added to a solution, cooled to −22° C., of sodium hydroxide (724 g) in water (4.8 l). Bromine (578 g) was metered into this solution such that a temperature of −15° C. was not exceeded. A solution of 1-(2-phenylhexahydro-2,5-methanopentalen-3a-yl)ethanone (290 g) in dioxane (600 ml) was metered into this solution, and the reaction was allowed to warm up gradually to room temperature. tert-Butyl methyl ether was added. Subsequently, water was metered in (2.5 l). After phase separation, the aqueous phase was washed with tert-butyl methyl ether. Subsequently, after addition of tert-butyl methyl ether (5 l), hydrochloric acid (32%) was used to establish a pH of pH 1.5. After phase separation, the organic phase was washed repeatedly with water and clarified with activated carbon. The solvent was changed by distillation under reduced pressure with addition of diisopropyl ether. After extractive stirring with diisopropyl ether at reflux, 2-phenylhexahydro-2,5-methanopentalene-3a-carboxylic acid (292 g) was obtained as a solid with 95% purity.

Provenance & Evidence