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.

Photoredox‐Catalyzed Thiocyanative Cyclization of Biaryl Ynones to Thiocyanated Spiro[5.5]trienones: An External‐Oxidant‐ and Transition‐Metal‐Free Approach

“…So, the excited state photocatalyst can oxidize both NH 4 SCN and 1 a , furthermore, the fluorescence quenching experiment revealed that the SET process was feasible between 1 a and the excited state photocatalyst (Figure 2). Initially, under blue light irradiation, 4CzIPN transformed to 4CzIPN*, which subsequently oxidized 1 a to its corresponding radical cation $${{1\hskip0.17em{\bf a}}^{\bullet +}}$$ [34c] and furnishing photocatalyst radical anion $${{4{\rm C}{\rm z}{\rm I}{\rm P}{\rm N}}^{\bullet -}}$$ . Next, the radical cation of 1 a combined with thiocyanate anion and produced vinyl radical A , which subsequently experiences an intramolecular 6‐exo‐trig cyclization, creating the spiro radical B .…”

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO 2 via Visible-Light-Induced Reductive Dearomatization

“…In recent years, visible-light photoredox catalysis [36][37][38][39][40][41][42][43][44][45] has emerged as a promising strategy for developing mild protocols for dearomatization, [46][47][48][49][50][51][52][53][54][55][56][57][58][59] including several significant protocols for the dearomatization of nonactivated arenes, [60][61][62][63][64][65][66][67][68][69][70][71][72][73][74] such as dearomative cycloadditions that were mainly from the groups of Sarlah and Bach, [60][61][62][63] and oxidative dearomatization. [64][65][66] A distinct redox-neutral hydroalkylative dearomatization of naphthalene derivatives was also reported by the group of Zhang, Mei and You.…”

“…[64][65][66] A distinct redox-neutral hydroalkylative dearomatization of naphthalene derivatives was also reported by the group of Zhang, Mei and You. 67 However, there are only a handful of reports on visible-light-induced reductive dearomatization of non-activated arenes. [68][69][70][71][72][73][74] Of particular note, the groups of König 68 and Miyake 69 independently reported the challenging photoredox catalyst (PC) induced Birch-type reduction of arenes.…”

Spirocyclizative Remote Arylcarboxylation of Non-Activated Arenes with CO2 via Visible-Light-Induced Reductive Dearomatization

“…In recent years, visible-light photoredox catalysis [35][36][37][38][39][40][41][42][43][44] has emerged as a promising strategy for developing mild protocols for dearomatization, [45][46][47][48][49][50][51][52][53][54][55][56][57][58] including several significant protocols for the dearomatization of nonactivated arenes, [59][60][61][62][63][64][65][66][67][68][69][70][71][72][73] such as dearomative cycloadditions mainly from the groups of Sarlah and Bach, [59][60][61][62] and oxidative dearomatization. [63][64][65] A distinct redox-neutral hydroalkylative dearomatization of naphthalene derivatives was also reported by the group of Zhang, Mei and You.…”

“…[63][64][65] A distinct redox-neutral hydroalkylative dearomatization of naphthalene derivatives was also reported by the group of Zhang, Mei and You. 66 However, there are only a handful of reports on visible-light-induced reductive dearomatization of non-activated arenes. [67][68][69][70][71][72][73] Of particular note, the groups of König 67 and Miyake 68 independently reported the challenging photoredox catalyst (PC) promoted Birch-type reduction of arenes.…”