Intermolecular Dearomatization of Naphthalene Derivatives by Photoredox‐Catalyzed 1,2‐Hydroalkylation

Abstract

An intermolecular hydroalkylative dearomatization of naphthalenes with commercially available α‐amino acids is achieved via visible‐light photoredox catalysis. With an organic photocatalyst, a series of multi‐substituted 1,2‐dihydronaphthalenes are obtained in good‐to‐excellent yields. Intriguingly, by tuning the substituents at the C2 position of naphthalenes, formal dearomative [3+2] cycloadditions occur exclusively via a hydroalkylative dearomatization–cyclization sequence. This overall redox‐neutral method features mild reaction conditions, good tolerance of functionalities, and operational simplicity. Diverse downstream elaborations of the products are demonstrated. Preliminary mechanistic studies suggest the involvement of a radical–radical coupling pathway.

Organic thermally activated delayed fluorescence (TADF) compounds used in photocatalysis

“…Penultimately, the intermolecular dearomatization of naphthalene derivatives by 1,2-hydroalkylation (Fig. 27d) 171 occurs analogously to the previous example. Stern-Volmer experiments indicated the naphthalene derivative oxidatively quenches the excited PC at a significantly faster rate than the carboxylic acid (Stern-Volmer constant, K SV , = 3870 and 253, respectively, in MeCN and 3068 and 232, respectively, in THF).…”

“…27c), 170 the intermolecular dearomatization of naphthalene derivatives by 1,2-hydroalkylation (Fig. 27d) 171 and the decarboxylative radical addition bifunctionalization cascade for the production of 1,4-amino alcohols (Fig. 27e).…”

Protonation-Enhanced Reactivity of Triplet State in Dearomative Photocycloaddition of Quinolines to Olefins

“…Dearomatization of arenes is challenging because of the high chemical stability inherent due to aromaticity. Despite this, chemists have developed various dearomative transformations of arenes, which are currently indispensable tools for synthesizing complex molecules. − Photochemical methods are a common approach to induce the loss of aromaticity. − In particular, visible-light photocatalysis has emerged as an efficient and environmentally friendly tool for utilizing energy transfer − and electron transfer, − enabling sustainable reactions, including various dearomative reactions. − …”

Radical boron migration of allylboronic esters

“…Photoredox-catalyzed and electrochemical dearomatization involving radicals have been explored with proven utility. [44][45][46][47][48][49][50] During the investigation of this 5-exo-trig cyclization process, we also observed the 6-exo-trig cyclization dearomatizated products in the reaction mixture. [51][52][53] As valuable pharmacophores, cyclic sulfones have been widely applied in medicinal chemistry and organic photoconducting materials due to their unique electronical and optical properties.…”