Visible‐Light‐Induced Intramolecular Double Dearomative Cycloaddition of Arenes

Abstract

Herein we report visible‐light‐induced intramolecular double dearomative cycloaddition of arenes. Compared with the well‐known photodimerization of arenes under ultraviolet irradiation, the current reactions are carried out under mild conditions and feature wide substrate scope. A large array of structurally‐diverse polycyclic indoline derivatives is afforded in high yields (up to 98 %) with exclusive diastereoselectivity (>20:1 dr) via dearomative [4+2] or [2+2] pathway.

Direct Construction of Fused/Bridged 3D Rings via Visible‐Light Induced Dearomative Cycloaddition of Arenes

“…Interestingly, inspired by the report of You group, [10f] a simple monitoring of the reaction by 1 H NMR showed that the dearomative cycloadditions of naphthalenes under visible‐light proceed in either [2+2] or [4+2] manifold (Figure 3). Another compound 34 a is characterized as the dearomative [2+2] adduct, which was observed rapid accumulation in the early stage of the reaction but gradual disappearance as the reaction proceeded.…”

Recent advances in the dearomative functionalisation of heteroarenes

“…41 Scheme 36 Visible-light-induced intramolecular double dearomative cycloaddition of arenes. 42 Scheme 37 Photoredox asymmetric nucleophilic dearomatisation of indoles with neutral radicals. 43 Scheme 38 Organophotocatalytic dearomatisation of indoles, pyrroles and benzo(thio)furans via a Giese-type transformation.…”

“…Additionally, in 2021, You reported an intramolecular double dearomative [4 + 2] cycloaddition of indoles bearing a pendant 1-naphthyl ring ( Scheme 36 ). 42 Furthermore, a dearomative [2 + 2] cycloaddition reaction was facilitated when tethered heterocycles were introduced ( e.g. 2/3-furyl, 2-benzofuryl and 3-indolyl).…”

Visible‐Light‐Induced Diradical‐Mediatedipso‐Cyclization towards Double Dearomative [2+2]‐Cycloaddition or Smiles‐Type Rearrangement

“…In this field, intensively exploring the synthetic utilities of transient, energetic, and highly reactive diradical species generated via ππ* excited indole rings is of much academic significance [4] . Using (hetero)arenes as acceptor of diradical species to get a high‐energy, transient double dearomative diradical (DDDR) species via ipso ‐cyclization, deserves investigation but has been rarely reported [5] …”