13C and1H NMR spectra of biologically active compounds. VII. Diastereomers of 2,2-dialkylspiro[cyclopropane-3,3′-indene]-1-carboxylic acids of the pyrethroid series

Abstract

The structures have been established and the stereochemical assignments have been made of eight pairs of diastereomers and three quartets of stereoisomers of esters of 2,2-dialkylspiro[cyclopropane-3,3′-indene]-1-carboxylic acids of the pyrethroid series by the methods of13C NMR spectroscopy using the shift reagent Eu(fod)3. Criteria have been found for assigning the stereoisomers on the basis of the characteristic values of the13C NMR chemical shifts of the signals of the methyl groups at C-2 for determining configuration of the substituents of the cyclopropane moiety of the molecule and of the C-2 signal itself for identifying isomers with respect to the side chain of the pyrethroid molecule. Criteria are proposed for identifying stereoisomers from the chemical shifts of the protons of the gem-dimethyl groups at C-2 in the1H NMR spectra.