1971 Volume 44 Issue 10 Pages 2795-2797
The solvent polarity-dependence of asymmetric stereochemistry was unambiguously corroborated in the Michael type cyclopropane formation in a system designed so as to proceed through the transition state conformations of an equal dipole moment not involving any geometrical isomerism: the NaH-catalyzed condensation of (−)-menthyl methacrylate with ethyl chloromalonate in solvent media of varying polarity resulted in the formation of (−)-1-methylcyclopropane-1,2,2-tricarboxylic acid having the same sign of rotation in all cases. The fit of the stereochemistry to the Kirkwood equation was borne out by the linearity found for the plots of logR⁄S against the Kirkwood-Onsager parameter. The R-configuration of (−)-1-methylcyclopropane-1,2,2-tricarboxylic acid was established by the correlation to (+)-2,2-diphenyl-1-methylcyclopropanecarboxylic acid of the well-defined (R)-configuration.
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