Stereomutation of conformational enantiomers of 9-isopropyl-9- formylfluorene and related acyl derivatives

Article abstract of DOI:10.1021/jo8008897

(Figure Presented) Low-temperature NMR spectra show that the title compound exists as a pair of conformational enantiomers, generated by the restricted rotation about the C9-Prⁱ bond, the corresponding interconversion barrier being 6.9 kcal mol^-1. This interpretation is supported by theoretical (MM and DFT) calculations and by the experimental determination of the analogous barriers occurring in the related MeC=O and Bu^tC=O derivatives.