EnT-Mediated Amino-Sulfonylation of Alkenes with Bifunctional Sulfonamides: Access to β-Amino Sulfone Derivatives

Photosensitized Imino-Thiocyanation of Alkenes

A metal-free photosensitized 1,2-imino-thiocyanation of olefins has been established by using the easily accessible bifunctional reagent S-cyano-N-(diphenylmethylene) thiohydroxylamine. A wide range of olefins were successfully transformed into the corresponding β-iminothiocyanates in moderate to high yields. This protocol stands out for its metal-free nature, broad substrate compatibility, and high atom and step economy, providing an effective strategy for assembling β-amino thiocyanate-containing scaffolds.

Regio- and Stereoselective β-Sulfonylamination of Alkynes via Photosensitized Bifunctional N-S Bond Homolysis

Nitrogen central radicals (NCRs) are versatile synthetic intermediates for creating functional nitrogen-containing molecules. Herein, a photosensitized β-sulfonylamination of terminal alkynes as well as acetylene has been established by employing N-sulfonyl heteroaromatics as bifunctional reagents (BFRs) to efficiently deliver versatile (E)-β-sulfonylvinylamines with excellent regio- and stereoselectivities. Mechanistic studies suggest a base-accelerated energy transfer (EnT) photocatalysis involving aromatic NCR formation, radical addition to alkynes, and sulfonylation processes.

Photocatalytic Synthesis and Functionalization of Sulfones, Sulfonamides and Sulfoximines

Sulfur(VI)-based functional groups are popular scaffolds in a wide variety of research fields including synthetic and medicinal chemistry, as well as chemical biology. The growing interest in sulfur(VI)-containing molecules has motivated the scientific community to explore new methods to synthesize and modify them. Here, photocatalysis plays a key role granting access to new types of reactivity under mild reaction conditions. In this Perspective, we present a selection of works reported in the last six years focused on the photocatalytic assembly and reactivity of sulfones, sulfonamides, and sulfoximines. We addressed the key synthetic intermediates for each transformation, while discussing limitations and strength points of the protocols. Future directions of the field are finally presented.

Photoinduced EnT-mediated sulfonamidylimination of alkenes and (hetero)arenes with iminophenylacetic acid oxime esters

A photoinduced EnT-mediated generation of sulfonamidyl radicals has been accomplished using rationally designed iminophenylacetic acid oxime ester reagents under metal-free conditions. This approach offers a mild, regio- and diastereoselective synthesis of N-sulfonyl diamines via diamination of alkenes and (hetero)arenes.

Photosensitized 1,2-Difunctionalization of Alkenes to Access β-Amino Sulfonamides

A metal-free photosensitized 1,2-imino-sulfamoylation of olefins by employing a tailor-made sulfamoyl carbamate as the difunctionalization reagent has been established. This protocol exhibits versatility across a broad substrate scope, including aryl and aliphatic alkenes, leading to the synthesis of diverse β-imino sulfonamides in moderate to good yields. This method is characterized by its metal-free reaction system, mild reaction conditions, excellent regioselectivity, and high atom economy, serving as a promising platform for the preparation of β-amino sulfonamide-containing molecules, particularly in the context of drug discovery.

Visible-Light-Induced Decarboxylative Aminosulfonylation of (Hetero)aryl Carboxylic Oxime Esters

Sulfonamides are important structures in pharmaceuticals, agrochemicals, and organocatalysts, yet the rapid and benign synthesis of these compounds is still a great challenge. Herein we report a photoinduced method for synthesizing sulfonamides from (hetero)aryl carboxylic acid oxime esters. This reaction proceeds via one-pot cascade radical-radical cross-coupling by energy-transfer-mediated photocatalysis. A wide substrate scope including (hetero)aryl substrates and late-stage modification of pharmaceutical molecular entities reveal its generality.

Three-Component Photochemical 1,2,5-Trifunctionalizations of Alkenes toward Densely Functionalized Lynchpins

Radical remote 1,n-difunctionalization reactions (n > 2) of alkenes are powerful tools to efficiently introduce functional groups with selected distances into target molecules. Among these reactions, 1,5-difunctionalizations are an important subclass, leading to sought-after scaffolds, but typically suffer from tailored starting materials and strict limitations for the formed functional group in 2-position. Seeking to address these issues and to make radical 1,5-difunctionalizations of alkenes more applicable, we report a novel three-component 1,2,5-trifunctionalization reaction between imine-based bifunctional reagents and two distinct alkenes, driven by visible light energy transfer-catalysis. Key to achieving this selective one-step installation of three different functional groups via the choreographed formation of four bonds was the utilization of a 1,2-boron shift and the rigorous capitalization of radical polarities and stabilities. Thorough mechanistic studies were carried out, and the synthetic utility of the obtained products was demonstrated by various downstream modifications. Notably, in addition to the functionalization of individual functional groups, their interplay gave rise to a unique array of cyclic products.