The Synthesis of S-(+)-2,2-Dimethylcyclopropane Carboxylic Acid: A Precursor for Cilastatin.

Abstract S -(+)-2,2-Dimethylcyclopropane carboxylic acid, a precursor for cilastatin, was prepared from 2-methylpropene and chiral iron carbene in three steps. Asymmetric cyclopropanation reaction of 2-methylpropene with iron carbene complex having chirality at the carbene ligand, followed by exhaustive ozonolysis, produced S -(+)-2,2-dimethylcyclopropanecarboxylic acid of up to 92% ee. The absolute configuration of complexed chiral cyclopropane (−)- 8 was determined by X-ray crystallographic analysis.