Stereochemistry and Mechanism of ?-Assisted Solvolysis of endo-Bicyclonon-6-ene-3-methyl Tosylate

Article abstract of DOI:10.1021/ja00342a037

The stereochemistry of the title reaction in several solvents has been established by 2H NMR configurational analysis of the 2-adamantyl-4,4-d2 products obtained from the α,α-dideuterated reactant 6.Solvent nucleophilic attack occurs predominantly on the side of the 2-adamantyl position away from the initial reaction site, the stereoselectivity increasing with increasing solvent nucleophilicity.Tosylate ion return in each case studied exhibits mainly though less selectively the same stereochemistry, i.e., is predominantly a non-least-motion process.Solvolysis in 80percent aqueous ethanol in the presence of 0.06 M NaN3 produces only 1percent of 2-adamantyl azide.The results constitute strong evidence for reaction through bridged carbonium ions and demonstrate that the structures of the carbocations in the initial ion pairs along the direct route and the ? route to 2-adamantyl solvolysis products are markedly differentiated by the location of the counterion.