Dearomative Intramolecular Diels–Alder/Sulfur Extrusion Reaction of Thiophenes with Alkynes Using peri‐Substituted Naphthalene as a Tether

Abstract

Dearomative intramolecular Diels–Alder/sulfur extrusion reaction of thiophenes with alkynes successfully afforded fluoranthenes in moderate to excellent yields. The proximity of both reactive sites fixed at the peri‐position of naphthalene would play an important role in the progress of this reaction. Tri(o‐tolyl)phosphine effectively suppressed the side reactions as a sulfur scavenger.

Recent advances in the synthesis and applications of fluoranthenes

“…Recently, a similar intramolecular Diels–Alder reaction between thiophene and alkyne groups tethered by a naphthalene ring at the peri -positions was reported by Okitsu, Yakura and co-workers (Scheme 23). 76 An initial intramolecular Diels–Alder reaction of 94 at 150 or 190 °C was proposed to give intermediate 95 , which further afforded fluoranthenes 80 in good to excellent yields (49%-quant.) upon extrusion of sulfur.…”