Use of Bridge Annelation To Retain the Syn Stereochemstry of Metacyclophane Derivatives: A Route to an Elusive syn-Metacyclophanediene

Article abstract of DOI:10.1021/jo00254a010

Free-radical bromination of 9,10-di-m-tolylphenanthrene (6) afforded the anti and syn conformers of the bis(bromomethyl) derivative 7 with the barrier of interconversion estimated at 90 kJ mol^-1.Sodium sulfide coupling of 7 suprisingly yielded