Stereospecific π-versusσ-participation in solvolysis of tricyclononadienyl p-nitrobenzoates

Abstract

Acetolysis of the tricyclic p-nitrobenzoate (IIIs-PNB) yields exclusively the unrearranged (IIIs-OAc), whereas the less reactive epimer (IIIa-PNB) undergoes stereospecific and complete rearrangement to acetates (IV-OAc) and (VI-OAc); solvolysis in the (IIIs) series may be aided by cyclopropyl σ-participation, whereas that in the (IIIa) series involves back-side homoallylic π-participation during C–O heterolysis.