BASE-PROMOTED 1,2-ELIMINATIONS FROM ENDO-2-BICYCLO[2.2.1]HEPTYL HALIDES AND ARENESULFONATES

Base-solvent systems that provide clean bimolecular 1,2-elimination from endo-2-bicyclo[2.2.1]heptyl halides and arenesulfonates by suppressing competitive solvolysis and nortricyclene-forming 1,3-elimination are developed. The stereochemistries of elimination from exo-3-deuterio-endo-2-bromobicyclo[2.2.1]heptane (10) and exo-3-deuterio-endo-2-bicyclo[2.2.1]heptyl 2,4,6-triisopropylbenzenesulfonate (11) are assessed using these base-solvent systems. The competitive syn-endo and anti-exo-H elimination modes are found to be strongly influenced by base association. However, for dissociated alkoxide bases, the elimination stereochemistry is unaffected by changes in leaving group from halide to arenesulfonate, in base strength, and in base size. © 1990, American Chemical Society. All rights reserved.