Cyclophanes. VII. Naphthalene and phenanthrene cyclophanes for the synthesis of coronene

Abstract

A coupling reaction between 3,6-bis(bromomethyl)phenanthrene and p- xylene-α,α?-dithiol gave 2,11-dithia[3,3](3,6)phenanthroparacyclophane (4). Ring-contraction of the sulphonium salt (5)proceeded in low yield. However, a corresponding dimethyl cyclophane (12) reacted efficiently togive the desired ring-contracted [2,2]cyclophane (13). Wittig rearrangement of the cyclophane (4) gave a high yield of compound (7) which in turn was oxidized to the disulphoxide (8). Thermal elimination of methylsulphenic acid produced the diene (9) which could be photochemically cyclized to coronene. A similar series of reactions with 2,13-dithia[3,3](2,7)naphthalenophane (14) was effected. Oxidation, halogenation and photochemical reactions of both the naphthalene- and phenanthrene-based cyclophanes are reported.