Preferred conformations of labile alkyl-substituted+ unsaturated ketones can be determined quite readily by analysis of nmr and infrared spectra. For the series of ketones studied, correlations of structure with conformation show that the (8)-cis conformation is favored for those ketones having an 01 hydrogen and two p-alkyl groups. For methyl ketones with or- methyl and cis-p-alkyl groups, steric crowding results in a preferred nonplanar (for C= C ...
