Acrylic Acid → 7-Oxabicyclo[2.2.1]hept-5-ene-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

The inside of a three-neck flask (inside volume 500 ml) equipped with a thermometer and a mechanical stirrer was substituted with nitrogen, and distilled furan (136 g, 2.0 mol), acrylic acid (72 g, 1.0 mol) and diisopropyl ether (70 ml) as a solvent were charged therein. The mixture was cooled to an inner temperature of 2° C. To this mixed solution was added dropwise a solution (11 ml, 0.01 mol) of a borane-tetrahydrofuran complex (BH3.THF) in 0.93 M tetrahydrofuran over 10 min., while maintaining the inner temperature at not more than 2° C. After the completion of the dropwise addition, the mixture was stirred at the same temperature for 4 hr. The resulting crystals were collected by filtration through a glass filter, washed with diisopropyl ether (100 ml) cooled to not more than 5° C. and dried under reduced pressure for 2 hr. to give 7-oxabicyclo[2.2.1]hept-5-ene-2-carboxylic acid as colorless crystals (81 g, endo form:exo form=95:5, purity >99%, yield 58% based on acrylic acid).

Provenance & Evidence