1,4-Dimethyl-2,5-dioxabicyclo[2.2.1]heptane-3,6-dione: optical resolution, absolute configuration and circular dichroism
Abstract
The title dilactone has been resolved into its enantiomers (+)- (S,S)-1 and (–)-(R,R)- 1, whose absolute configurations were found by X-ray diffraction analysis of intermediate lactonic amide 2a; the magnitude of the n–π* Cotton effect increased with an increase in folding or a diminution in twist of the boat conformation of a dilactone ring.