Synthesis ofN-Containing Heterocyclic Compounds Using Visible-light Photoredox Catalysis

Abstract

Nitrogen heterocycles represent a highly important class of compounds which are widely used in materials science, agrochemistry, and medicinal chemistry. Therefore, there is continuing interest in the development of convenient, efficient, and environmentally benign synthetic methods for the construction of nitrogen containing heterocycles. Due to its natural abundance, ease of use, and promising application in industry, the use of visible light as a driving force for chemical reactions has received considerable attention in the past few years. This account summarizes the synthesis of N-heterocycles using visible-light photoredox catalysis published in the last two years, according to the size and type of the formed N-heterocyclic rings. In the context of seminal works of others in this area, a concise summary of the contributions of the authors is also offered.

Organo‐Photoredox Catalyzed Oxidative Dehydrogenation of N‐Heterocycles

“…Based on the above results and known literature, [9][10][11] we propose ap lausible mechanism as shown in Scheme 4. Initially, RB À2 absorbs the visible light (l max = 550 nm) to give ap hotoexcited singlet state, RB 2À *(S 1 ), which undergoes rapid intersystem crossingt oi ts lowest long-lived triplet state RB 2À *(T 1 ).…”

“…[2d] Recently,t he research groups of Beller and Stahl independently reportedt he oxidative dehydrogenation of 1,2,3,4-tetrahydroquinolines and other important N-heterocyclesu sing ah eterogeneous iron oxide (FeOx@NGr-C) and cobalt oxide (Co 3 O 4 -NGr/C) based catalytic system supported on nitrogen-doped carbon, respectively. [2j] Here,t he first reporto fcatalytic oxidative dehydrogenation of diverseN -heterocycles by av isible-light [9] organo-photoredox catalyst is reported. Kim and co-workers have reported the CuI/DBAD based dual catalytic system for the dehydrogenation of tetrahydroquinolines under aerobic conditions.…”

“…Kim and co-workers have reported the CuI/DBAD based dual catalytic system for the dehydrogenation of tetrahydroquinolines under aerobic conditions. [2j] Here,t he first reporto fcatalytic oxidative dehydrogenation of diverseN -heterocycles by av isible-light [9] organo-photoredox catalyst is reported. The reactionp roceeds efficiently under base-free and additive-free conditions with ambienta ir as the source of O 2 at room temperature.…”

Rhodium(III)-Catalyzed Redox-Neutral [3+3] Annulation of N-nitrosoanilines with Cyclopropenones: A Traceless Approach to Quinolin-4(1H)-One Scaffolds

“…Quinolin-4(1H)-ones are ubiquitously present in numerous natural products and drugs, representing an important class of privileged structures in medicinal chemistry [1][2][3][4][5], such as antibiotics norfloxacin and gatifloxacin, a HIV integrase inhibitor, elvitegravir, and a modulator of ATP-binding cassette transporters, lvacaftor (Figure 1). Therefore, the development of highly efficient protocols both in transition-metal-catalyzed C-H activation and photocatalytic methods for the construction of such N-heterocyclic scaffolds is an extremely hot issue in modern organic chemistry [6][7][8][9][10][11][12]. However, the existing methodologies usually require elaborate-to-access starting materials, multiple steps, or harsh reaction conditions, failing to implement a wide range of applications.…”

An Efficient Regioselective Access to (11Z)‐11‐(3‐Aryl‐5,6‐dihydropyrazin‐2(1H)‐ylidene)‐11H‐indeno[1,2‐b]quinoxaline Derivatives via One‐Pot Three‐Component Reaction

“…The varied class of nitrogen‐containing heterocycles includes a broad fraction of organic products, many of which have found significant applications in agrochemistry, material science, and medicinal chemistry . Thus, there is continuing attention in the expansion of an expeditious, atom‐economic, and environmentally benign synthetic procedures for the preparation of N ‐heterocyclic compounds …”