Visible-light-induced synthesis of benzothiophenes and benzoselenophenes via the annulation of thiophenols or 1,2-diphenyldiselane with alkynes

Sustainable access to benzothiophene derivatives bearing a trifluoromethyl group via a three-component domino reaction in water

A catalyst-free three-component domino reaction was developed for the synthesis of benzothiophene fused pyrrolidones bearing a CF3 group for the first time. The notable advantages of this strategy over the existing methods include the use of water as a solvent at room temperature, transition metal-free conditions, a broad substrate scope, and easy scale-up synthesis. More importantly, the benzothiophene derivatives have been found to show potent anticancer activities using the Cell Counting Kit-8 (CCK-8) assay.

Visible-Light-Induced Formation of Thiavinyl 1,3-Dipoles: A Metal-Free [3+2] Oxidative Cyclization with Alkynes as Easy Access to Thiophenes

A visible-light-induced [3+2] oxidative cyclization of various alkynes with easily available ketene dithioacetals as the previously unknown thiavinyl 1,3-dipoles in the presence of an acridine photosensitizer is reported. A series of multisubstituted thiophenes were achieved regioselectively in ≤98% yields under very mild metal-free conditions without other additives. This reaction could tolerate a wide range of substrates and achieve good efficiency in large-scale syntheses. The reaction mechanism and their applications are described in detail to reveal the reactivity of the new 1,3-dipoles and the selectivity of the reactions.

Divergent Construction of Benzothiophene-Fused N-Heterocycles via Stereotunable Three-Component Domino Reactions

A stereotunable three-component domino strategy among thioisatin, 2-bromo-1-phenylethan-1-one, and cyclohexane-1,2-diamine under catalyst-free conditions was disclosed. A wide range of benzothiophene-fused polycycles and eight-membered N-heterocycles were synthesized by regulating the stereoconfiguration of cyclohexane-1,2-diamines. The detailed mechanism and the origin of the chemoselectivity were explored by density functional calculations. Analysis of the geometrical structures of key transition states revealed that the existence of favorable intramolecular attractions, and the steric effect governed the chemoselectivity observed.

Recent Progress in the Synthesis of Benzo[b]thiophene

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Due to such a wide range of applicability, the synthesis of benzo[b]thiophene derivatives has attracted intensive research. Numerous mild and efficient approaches for the synthesis of benzo[b]thiophenes have been developed over the years. Different catalysts and substrates have been applied for benzo[b]thiophene synthesis. This review will focus on the studies in the construction of benzo[b]thiophene skeleton, which date back from 2012.

Recent applications of Rose Bengal catalysis in N-heterocycles: a short review

The visible light harnessing ability of Rose Bengal, an organic dye, has been extensively employed in organic chemistry over the last few years. In visible light mediated reactions, this photoredox catalyst operates through multiple pathways and has the ability to provide distinctly different and valuable results. The most significant of these results are bond creation, bond functionalization, particularly for C–H and C–heteroatom bonds, and cross couplings. It is crucial to study these cases whenever these bond formations and couplings lead to the formation of heterocyclic compounds or their functionalization. The diverse biological activity and medicinal applications of heterocyclic compounds is an extensively explored area. This review primarily attempts to demonstrate the synthetic potential of Rose Bengal for synthesis and site selective functionalization of nitrogen containing heterocycles.

The recent applications of Rose Bengal as a photocatalyst for the synthesis and functionalization of N-heterocycles have been discussed.

Photocatalytic formation of carbon-sulfur bonds

This review summarizes recent developments in photocatalyzed carbon-sulfur bond formation. General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways.

Air promoted annulation of thiophenols with alkynes leading to benzothiophenes

Air promoted intermolecular annulation of thiophenols with alkynes, leading to complex benzothiophenes, is reported.