Lightner DA, Eng FP. The octant rule VIII. Variable temperature circular dichroism spectra of alpha-methyl- and methoxyl-substituted 5 alpha-cholestan-2- and -3-ones.
Steroids 1980;
35:189-207. [PMID:
7376218 DOI:
10.1016/0039-128x(80)90102-6]
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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.
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