α-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

Article abstract of DOI:10.1021/jo00346a006

Nitration of the most substituted (thermodynamically more stable) enol acetate or trimethylsilyl ether of 2-methylcyclohexanone and the phase-transfer methylation of 2-nitrocyclohexanone serve as methods of preparation of 2-methyl-2-nitrocyclohexanone, whereas nitration of the least substituted enol acetate or trimethylsilyl ether of 2-methylcyclohexanone and methylation of the dianion of 2-nitrocyclohexanone lead to cis- and trans-6-methyl-2-nitrocyclohexanone.Nitration of the enol acetate or trimethylsilyl ether of 2,6-dimethylcyclohexanone and methylation of either2-methyl-2-nitro- or 6-methyl-2-nitrocyclohexanone are methods of preparation of cis- and trans-2,6-dimethyl-2-nitrocyclohexanone. 1H NMR chemical shift and coupling constant data were used to determine the preferred conformations of the cyclohexanones: 2(e)-methyl-2(a)-nitro, cis-6(e)-methyl-2(e)-nitro, trans-6(e)-methyl-2(a)-nitro, cis-2(e),6(e)-dimethyl-2(a)-nitro, trans-2(a)-methyl-6(e)-methyl-2(e)-nitro.