Intramolecular Alkoxide Induced Heterolysis of Perhydronaphthalene-1,4-diol Monosulfonate Esters through Orbital Interactions over Three C-C Single Bonds

Article abstract of DOI:10.1021/jo00057a037

The course of the reactions that occur when stereochemically rigid trans-perhydronaphthalene-1,4-diol monosulfonate esters (1-4) are treated with alkali metal tert-amylate in refluxing benzene depends on the relative orientation of the leaving group and the tertiary hydroxyl group.An equatorial sulfonate ester group homofragmentation leading to the cyclopropane derivative 15.In case of an axial sulfonate ester group β-elimination, which strongly depends on the stereochemistry of the tertiary deprotonated hydroxyl group, is the main reaction path.The O-silylated mesylates 5 and 6 show no reaction at all upon treatment with strong base; fast reactions are observed when 5 and 6 are treated with TBAF.Generation of an alcoholate is crucial for the observed reactions.Homofragmentation and an internal return reaction with inversion of configuration of the mesylate group in the axial mesylates 1 and 3 is explained by assuming a stabilized 1,3-bridged intermediate carbocation.This also explains why the equatorial mesylates react slightly faster than the axial mesylates.The reactivity of the α-mesylates is controlled by through-bond induction alone, whereas the reactivity of the corresponding β-mesylates is determined by the sum of a through-bond and a through-space (1,3-bridging) interaction.