Abstract
The geometrical isomers of O-4-tert-butylcyclohexyl methylthiocarbamate were prepared by way of the corresponding dithiocarbonates. The O-trans-isomer was obtained from a mixture of cis- and trans-4-tert-butylcyclohexanols via an alkoxide formation involving biassed equilibration, whereas the O-cis isomer was from the cis-cyclohexanol via an alkoxide formation free from equilibration.
The acid-catalyzed rearrangement of the O-cis thiocarbamate gave a 1:3 mixture of S-cis- and S-trans-4-tert-butylcyclohexyl methylthiocarbamates, whereas that of the O-trans thiocarbamate afforded a 9:1 mixture of S-cis and S-trans products.
These results, together with the data from a study on the reactions of O-cis-3, 3, 5-trimethylcyclohexyl methylthiocarbamate and the O-neopentyl analog, indicate that the acid-catalyzed rearrangement proceeded mostly through an SN2 type of transalkylating mechanism to give the S-isomer in the case where the approach of nucleophiles was not sterically blocked, otherwise the reaction gave SNl-type products.
