ANALYSIS OF CYCLOHEPTANONE CONFORMATION FROM TEMPERATURE-DEPENDENT CIRCULAR-DICHROISM MEASUREMENTS OF (+)-(3R)-METHYLCYCLOHEPTANONE AND (-)-(4R)-METHYLCYCLOHEPTANONE

Conformational analysis of methylcycloheptanones was achieved by relating CD rotational strengths to conformational free energies. Twist conformers with C1 on the symmetry axis (TC1) were found to be more stable than those with C2 or C7 on the symmetry axis (TC2 or TC7). The free energy differences were found to range from 0.2 to 1.2 kcal mole. A similar analysis of (+)(3R)-methylcyclohexanone showed the equatorial chair conformer to be most stable, by 0.50-0.75 kcal mole. © 1979.