The thermal decomposition of quaternary ammonium hydroxides. Part IV. Methohydroxides of cis- and trans-2-alkyl-NN-dimethylcyclohexylamines: evidence for elimination from a twist boat conformation.

Abstract

The thermal decomposition of the methohydroxides of a number of cis- and trans-2-alkyl-NN-dimethylcyclohexylamines has been studied by quantitative analysis of the olefinic products. The methohydroxides of all the cis-bases give an olefin mixture consisting largely (91–99%) of the 1-alkylcyclohexene; the methohydroxides of all the trans-bases give an olefin mixture consisting almost entirely (94–100%) of the 3-alkylcyclohexene. These results are rationalised in terms of E₂ eliminations from molecules in which the cyclohexane ring adopts a twist boat conformation.