The preparations and spectroscopic properties are described of 4,4-dimethyl-, 3,4,4-trimethyl-, 3-ethyl-4,4-di-methyl-, 3,4,4,5-tetramethyl-, 3,5-diethyl-4,4-dimethyl-, 2,4,4-trimethyl-, and 2,4,4,5-tetramethylcyclohexa-2,5-dienones, and related cyclohexenones and Cyclohexanones. The stereochemistry of the related series of 2,6-dibromocyclohexanones is discussed, and various stereochemical criteria are compared. Spectroscopic data for 3,4,4-trimethylcyclohex-2-enone are given; n.m.r. solvent shift and other data were used to confirm that the major product in a recently reported preparation of this compound is in fact 3,6,6-trimethylcyclohex-2-enone.