Diazomethane → Methyl (1R,2R)-2-(3-chlorophenyl)cyclopropane-1-carboxylate

Participants

Reaction Steps

Diazomethane in ether was generated by adding portionwise N-nitroso-N-methyl urea to a biphasic mixture of ether (100 mL) and 2.5 M KOH in water (150 mL). The ether layer was transferred by pipette to a solution of 3-chlorocinnamic acid (1.00 g, 5.48 mmol, 1 equiv.) and palladium(II) acetate (6 mg, 0.028 mmol, 0.005 equiv.) in dichloromethane: ether (1:2, 150 mL) at 0° C. The addition was continued until a persistent yellow color remained in the solution. Stirring was continued for 2.5 h at 0° C., then approximately 3 mL acetic acid were added and the mixture was left standing at room temperature overnight. The resulting mixture was washed twice with saturated aqueous NaHCO3 solution and once with brine. It was then dried (MgSO4), filtered, and the solvent was removed in vacuo. The crude trans-2-(3-chlorophenyl)-cyclopropanecarboxylic acid methyl ester (1.09 g, 5.17 mmol, 94%) was obtained as a yellow oil.

Provenance & Evidence