.alpha.-Nitro ketones. 6. Synthesis and conformation of 2-methyl-2-nitro-, cis- and trans-6-methyl-2-nitro-, and cis- and trans-2,6-dimethyl-2-nitrocyclohexanones
.alpha.-Nitro ketones. 6. Synthesis and conformation of 2-methyl-2-nitro-, cis- and trans-6-methyl-2-nitro-, and cis- and trans-2,6-dimethyl-2-nitrocyclohexanones