(1S-trans)-2,2-Dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarbonyl chloride → (1R-trans)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarbonyl chloride

Participants

Reaction Conditions

Reaction Steps

In a 200 ml flask, there were charged (-)-trans-2,2-dimethyl-3-isobutenylcyclopropane-1-carboxylic acid chloride (30.0 g) and toluene (70 g). Thereafter, boron trichloride (0.94 g) was added thereto at 0° C. with stirring under a nitrogen atmosphere, and the reaction was carried out for 10 minutes. After removal of the catalyst, the toluene was recovered by distillation, and the residue was distilled to obtain racemized 2,2-dimethyl-3-isobutenylcyclopropane-1-carboxylic acid chloride (27.0 g) having a boiling point of 72°-78° C./2 mmHg. The proportion of the optical isomers in this product was determined by gas chromatography. The result was as follows: (+)-trans, 46.8%; (-)-trans, 46.7%; (+)-cis, 3.3%; (-)-cis, 3.2%.

Provenance & Evidence