CYCLOPROPANE-1,1 prime -INDENES.

Article abstract of DOI:10.1021/ja00316a036

The relative concentrations of stereoisomers in product mixtures were determined as a function of time by using a combination of analytical techniques: vapor phase chromatography, polarimetry, NMR spectroscopy, and NMR spectroscopy in the presence of an optically active lanthanide shift reagent. The stereochemical reaction kinetics reveal that the Smith mechanism is not a plausible model for one-center epimerization; two trimethylenes, produced through two distinct cyclopropane C-C bond cleavages, are implicated, since all three possible one-center epimerizations are seen.