137724-75-5Relevant academic research and scientific papers
Reactions of Cyclohexane Derivatives in Superacids
Dean, Christopher,Whittaker, David
, p. 1541 - 1543 (2007/10/02)
The reactions of menthol with FSO3H-SO2 and neomenthyl chloride with SbF5-SO2ClF follow different routes.The first yields a substituted cyclopentyl cation and the second a substituted cyclohexyl cation.Experiments on substituted cyclohexyl chlorides show that replacement of all the hydrogen atoms on the next but one carbon atom to the reaction centre blocks formation of a carbocation.It is suggested that ionisation of an equatorial chlorine atom takes place with assistance from an intramolecular electronic interaction, forming the methyl cyclopentyl carbocation in a synchronous process, rather than stepwise via the cyclohexyl carbocation.Reasons for contrasting behaviour in solvolytic reactions are discussed.
Terpenoid Ether Formation in Superacids
Carr, Graham,Dean, Cristopher,Whittaker, David
, p. 351 - 354 (2007/10/02)
A number of terpenoid bicyclic ethers have been prepared by cyclisation of suitable precursors in fluorosulphuric acid-sulphur dioxide.The products are formed under a mixture of thermodynamic and kinetic control, and five-, and six-, and seven-membered-ring ethers are obtained.Both primary and secondary alcohols have been cyclised by attack of the hydroxy group on carbocation centres generated by protonation of alkenes or ionisation of tertiary alcohols; tertiary alcohols ionise too readily to provide an etheral oxygen atom.Reaction of the unsaturated secondary alcohol dihydrocarveol (2) with antimony pentafluoride in sulphur dioxide gives the ether by a reaction which may not involve a carbocation, and hence may be suitable for ether formation from substrates which rearrange readily in acids.
