- Sep 13, 2018 -
(S)-(+)-2,2-dimethylcyclopropane carboxylic acid is the key intermediate of Cilastatin (an excellent inhibitor of dehydropeptidase-I). Using 2-methylbutenoic acid as raw material, 2,2-dimethylcyclopropane carboxylic acid was achieved via esterification, cyclopropanantion and hydrolysis, the yield is 44.1%. Specially, using zinc powder/copper (I) chloride-acetyl chloride as catalysts, the cyclopropanation proceedes easily with dibromomethane. Then 2,2-dimethylcyclopropane carboxylic acid is converted to acid chloride and reacted with L-carnitine oxalate (the chiral reagent for resolution). After fractional crystallization and hydrolysis, (S)-(+)-2,2-dimethylcyclopropane carboxylic acid was prepared with 16.7% yield. Thus a new synthesis route of 2,2-dimethylcyclopropane carboxylic acid was designed and its chiral resolution procedure was improved, this new route and improved procedure are clean, convenient to operate and apt for industrialization with lower cost.