Electrophilic additions to strained alkenes. II. The reaction of benzeneselenenyl chloride with tricyclo[4.2.2.02,5]deca-3,7-diene derivatives

Abstract

The reactions of benzeneselenenyl chloride with three derivatives of tricyclo[4.2.2.02,5]deca-3,7-diene have been investigated in four solvent systems: methylene chloride, acetic acid, acetic acid/LiClO4, and methanol. Under conditions of kinetic control only products of exo–anti attack upon the cyclobutene moiety are isolable when the solvent system is methylene chloride or acetic acid. This observation also holds in acetic acid/LiClO4 except in the case of dimethyl tricyclo[4.2.2.02,5]deca-3,7,9-triene-7,8-dicarboxylate where the major product is that of cross-bonding with solvent incorporation. In methanol products of solvent incorporation, transannular cross-bonding and lactonization (where possible) are observed. A general mechanistic scheme is proposed to account for these observations in accord with earlier results for the analogous arenesulphenylations.