Reductive Dimerization of 2-Substituted Cyclopropane-1, 1-dicarboxylates Using Samarium(II) Diiodide

Abstract

In the presence of samarium diiodide, 2-aryl and 2-heteroaryl cyclopropane-1, 1-dicarboxylic esters were readily dimerized to give 3, 4-disubstituted 1, 1, 6, 6-hexanetetracarboxylic esters as diastereomeric mixtures in moderate to good yields. The diastereomeric mixtures were separated by preparative HPLC and stereo-chemistries of the isolated meso and racemic compounds were determined on the basis of HPLC analysis on chiral stationary phases. Between the ¹H-NMR spectra of the separated diastereomers, the characteristic differences in the chemical shifts of the C2-H (C5-H) signals were observed and explained based on the MOPAC calculation.