Phenylhydrazine → Ethyl chrysanthemate

Participants

Reaction Conditions

Reaction Steps

19.64 mg (0.05 mmol) of a copper complex prepared from 9.98 mg (0.05 mmol) of copper acetate monohydrate and 18.23 mg (0.055 mmol) of (R)-N-salicylidene-2-amino-1,1-diphenylpropanol, and 6.09 (55 mmol) of 2,5-dimethyl-2,4-hexadiene were charged in a 50 ml Schlenk's tube wherein the atmosphere is substituted with nitrogen. After 5.4 mg of phenylhydrazine was further added, 1.14 g (10 mmol) of ethyl diazoacetate was added dropwise at 50° C. over 2 hours. After the completion of the dropwise addition of ethyl diazoacetate, the mixture was further stirred at 25° C. for 1 hour. The amount of chrysanthemic acid ethyl ester formed was determined by gas chromatography. As a result, it was 1.52 g and the yield was 77.7% based on ethyl diazoacetate and, furthermore, the trans/cis ratio was 61/39. After 2,5dimethyl-2,4-hexadiene (boiling point: 51° C./30 mmHg) was distilled off from the reaction mixture, 1 g of the concentrated solution was taken out. Then, 10 ml of an aqueous 1N sodium hydroxide solution and 5 ml of ethanol were added and alkali hydrolysis was performed by stirring at 100° C. for 1 hour. The resulting chrysanthemic acid was reacted with 1-menthol and the formed diastereomer ester was analyzed by gas chromatography. As a result, the optical purity of the (+)-trans isomer was 69% e.e., whereas, the optical purity of the (+)-cis isomer was 68% e.e.

Provenance & Evidence