Substituent increments for the 1H-NMR. Chemical shifts of the 18- and 19-methyl protons of steroids. Part I: 9beta, 10alpha(retro)-steroids

Substituent effects on the PMR signals of methyl groups in methyl steroids

Proton magnetic resonance (PMR) signals were assigned to each of the methyl groups for a variety of C-3 oxygenated 4-monomethyl, 6-monomethyl, 4, 4-dimethyl, and 2, 2-dimethyl steroids related to 5alpha-cholestane series. The effects of various substituents (i.e. methyls at C-4, C-6, or C-2, functional groups at C-3, and unsaturated bonds) on the methyl proton resonances have been derived from the assignment. The application of such data to structural and stereochemical problems has also been discussed.