Recent Advances on Metal-Free, Visible-Light- Induced Catalysis for Assembling Nitrogen- and Oxygen-Based Heterocyclic Scaffolds

Abstract

Heterocycles are important class of structures, which occupy a major space in the domain of natural and bioactive compounds. For this reason, development of new synthetic strategies for their controllable synthesis became of special interests. The development of novel photoredox systems with wide-range application in organic synthesis is particularly interesting. Organic dyes have been widely applied as photoredox catalysts in organic synthesis. Their low costs compared to the typical photocatalysts based on transition metals make them an excellent alternative. This review describes proceedings since 2015 in the area of application of metal-free, visible-light-mediated catalysis for assembling various heterocyclic scaffolds containing five- and six-membered rings bearing nitrogen and oxygen heteroatoms.

Transition Metal‐Free Synthesis of Carbo‐ and Heterocycles via Reaction of Alkynes with Organylchalcogenides

“…Despite their promising use, certain reactions often proceed at high temperatures and low regioselectivity. Thus, methods based on metal‐free conditions have aroused the interest of researchers for economic and environmental reasons [7–9] . In this sense, electrophilic halogenating reagents have gained space due to its high capacity to activate alkyne carbon‐carbon triple bonds with the advantageous to be incorporated in the product as a site for further transformations.…”

“…Thus, methods based on metalfree conditions have aroused the interest of researchers for economic and environmental reasons. [7][8][9] In this sense, electrophilic halogenating reagents have gained space due to its high capacity to activate alkyne carbon-carbon triple bonds with the advantageous to be incorporated in the product as a site for further transformations. Moreover, these protocols frequently involve benefits in terms of chemo-, regio-, and stereoselectivity.…”

Visible‐Light‐Induced Manganese‐Catalyzed Reactions: Present Approach and Future Prospects

“…Strategies involving visible‐light‐induced photoredox catalysis have been employed for the construction of various heterocycles as a mild and efficient method. Among the heterocycles, N ‐containing heterocycles are privileged structural motifs as they are found in numerous bioactive natural products and pharmaceutics [64,65] . This approach for the synthesis of N ‐containing heterocycles has been more recently advanced by the use of manganese as a photoredox catalysis.…”

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

“…It possesses a cyclic scaffold with carbon and three nitrogen elements in the ring [12][13][14][15]. An immense versatility of biological properties is possessed by 1,2,3-triazole heterocyclic systems, and many strategies are screened for the synthesis of these rings [16,17]. Notably, triazole rings exhibit various medicinal applications, such as usages as anticancer [18] anti-HIV [19], antimalarial [20], antiplasmodial [21], and antibacterial agents [1,22].…”