title: The octant rule VIII. Variable temperature circular dichroism spectra of alpha-methyl- and methoxyl-substituted 5 alpha-cholestan-2- and -3-ones.
abstract: 2 alpha- and 2 beta-Methyl- and methoxy-5 alpha-cholestan-3-ones and 3 alpha- and 3 beta-methyl- and methoxy-5 alpha-cholestan-2-ones have been synthesized and their variable temperature circular dichroism spectra obtained and analyzed. Rotatory strength (R) values for alpha-axial and equatorial CH3 and OCH3 groups are determined by difference measurements with the parent ketone. The (small) equatorial CH3 R-values do not consistently follow the Octant Rule. Axial OCH3 groups do not obey the Octant Rule ("anti-octant" behavior) and impose a bathochromic shift on the C = O n-pi transition. Equatorial OCH3 groups do not consistently follow octant or "anti-octant" behavior.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D002776:Cholestanes / Q000138:chemical synthesis; D002778:Cholestanones / Q000138:chemical synthesis; D002942:Circular Dichroism
chemical_list: D002776:Cholestanes; D002778:Cholestanones