13C Nuclear Magnetic Resonance Studies. 38. Examination of the Long-range Shielding Effects of the Hydroxyl Group in Alicyclic Systems

Abstract

The substituent effects of the hydroxyl group on the 13C shieldings of the trans-decalols and the 10-methyl-trans-decalols have been determined. The shifts for the carbons three and four bonds from the site of substitution depend strongly on their orientation with respect to the hydroxyl group. While the latter have not been widely recognized, these δ effects are valuable for spectral analysis and stereochemical assignments since these range up to 3.4 p.p.m. In direct contrast to the well established trends for γ effects, steric crowding of δ nuclei causes marked downfield shifts. The corresponding effects in several steroids are illustrated.