Helical Phenanthrenes, Part 5. Synthesis of Pentahelicene-7,8-dione via Intramolecular Benzoin Condensation

Abstract

The intramolecular benzoin condensation of [1,1'-binaphthyl]-2,2'-dicarbaldehyde (5), followed by oxidation with air, provides a new synthesis of (MP)-pentahelicene-7,8-dione (1). With reference to the original preparation of this quinone via acyloin condensation, its present yield (73% for the ring-closing step) is considerably increased.