Enantioselective Synthesis of Cyclobutane-fused Heterocycles via Lewis Acid-Catalyzed Dearomative [2+2] Photocycloaddition of Indoles, Benzofurans, and Benzothiophenes with Alkenes.

Cyclobutane-fused heterocycles are important motifs in biologically active molecules, yet their enantioselective synthesis remains a significant challenge. We report a broadly applicable and modular strategy for constructing these strained architectures through a visible-light-mediated, Lewis acid-catalyzed dearomative [2+2] photocycloaddition of indoles, benzofurans, and benzothiophenes with alkenes. The method employs a simple catalytic system based on commercially available rare-earth Lewis acids and chiral pyridine-2,6-bis(oxazoline) (PyBox) ligands.

Reconfiguration of Active Species under Light for Enhanced Photocatalysis.

Photocatalysis has emerged as a cornerstone of synthetic chemistry, enabling mild and selective transformations by using sustainable light sources. A common assumption persists that most photocatalysts are taken for granted to function as monomorphic species throughout the catalytic cycle. Our findings challenge this premise and discover a new mechanistic picture, demonstrating that the evolution of the catalyst under light is not a degradation artifact but a productive and exploitable transformation pathway.

Sulfur in Waste-Free Sustainable Synthesis: Advancing Carbon-Carbon Coupling Techniques.

This review explores the pivotal role of sulfur in advancing sustainable carbon-carbon (C-C) coupling reactions. The unique electronic properties of sulfur, as a soft Lewis base with significant mesomeric effect make it an excellent candidate for initiating radical transformations, directing C-H-activation, and facilitating cycloaddition and C-S bond dissociation reactions. These attributes are crucial for developing waste-free methodologies in green chemistry.

Reversible Radical Addition Guides Selective Photocatalytic Intermolecular Thiol-Yne-Ene Molecular Assembly.

In modern organic chemistry, harnessing the power of multicomponent radical reactions presents both significant challenges and extraordinary potential. This article delves into this scientific frontier by addressing the critical issue of controlling selectivity in such complex processes. We introduce a novel approach that revolves around the reversible addition of thiyl radicals to multiple bonds, reshaping the landscape of multicomponent radical reactions.

Exploring metallic and plastic 3D printed photochemical reactors for customizing chemical synthesis.

Visible light photocatalysis is a rapidly developing branch of chemical synthesis with outstanding sustainable potential and improved reaction design. However, the challenge is that many particular chemical reactions may require dedicated tuned photoreactors to achieve maximal efficiency. This is a critical stumbling block unless the possibility for reactor design becomes available directly in the laboratories.

Intermolecular Photocatalytic Chemo-, Stereo- and Regioselective Thiol-Yne-Ene Coupling Reaction.

The first example of an intermolecular thiol-yne-ene coupling reaction is reported for the one-pot construction of C-S and C-C bonds. Thiol-yne-ene coupling opens a new dimension in building molecular complexity to access densely functionalized products. The employment of Eosin Y/DBU/MeOH photocatalytic system suppresses hydrogen atom transfer (HAT) and associative reductant upconversion (via C-S three-electron σ-bond formation).