Citric Acid → (RS)-2-methyl-4-methylidene-3-ethyl-2-cyclopenten-1-yl (1R)-trans-3-(2,2-dichloro-vinyl)-2,2-dimethylcyclopropanecarboxylate

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Reaction Steps

625 mg of (1R)-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid chloride was added under ice-water cooling to a mixed solution of 400 mg of (RS)-2-methyl-4-methylidene-3-ethylcyclopent-2-en-1-ol, 5 mg of 2,6-di-t-butyl-4-methylphenol and 274 mg of pyridine in 6 ml of toluene. The reaction was continued at an ambient temperature for eight hours. The reaction solution was added to a 5% citric acid solution under ice-water cooling, and extracted three times with diethyl ether. The combined ether layer was washed successively with a saturated sodium hydrogencarbonate solution and a saturated sodium chloride solution, and dried over anhydrous magnesium sulfate. After removal of the solvent under reduced pressure, the residue was subjected to silica gel column chromatography to yield 781 mg of (RS)-2-methyl-4-methylidene-3-ethyl-2-cyclopenten-1-yl (1R)-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate (Compound No.5). Yield 82%. (Eluent: n-hexane/ethyl acetate=30/1, 2,6-di-t-butyl-4-methylphenol 0.1%) nD23 1.5251

Provenance & Evidence