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

摘要

[GRAPHICS] Low-temperature NMR spectra show that the title compound exists as a pair of conformational enantiomers, generated by the restricted rotation about the C9-Pr-i 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 (BuC)-C-t=O derivatives.