Visible Light-Induced Photocatalyst-Free Diastereoselective Iodosulfonylation of Cyclopropenes in Water.

This study presents a greener approach to the visible-light-induced micellar-catalyzed diastereoselective iodosulfonylation of cyclopropenes in a water medium. Remarkably, this process operates without a photocatalyst. Instead, it utilizes an electron-donor-acceptor complex formed between sulfonyl chloride and sodium iodide.

A Visible Light Photoredox Approach for Synthesizing Sulfone-Functionalized Cyclopropenes.

We have developed a tandem method essential for synthesizing sulfone-containing organic molecules, which has wide-ranging applications in agrochemicals, medicinal chemistry, and polymer science. This method involves a two-step process: an iodo-sulfonylated intermediate is formed initially, followed by elimination to regenerate the double bond, ultimately yielding sulfone-containing cyclopropenes. Control studies have confirmed the intermediacy of iodo-sulfonylated cyclopropane within the reaction sequence.

Electron Donor-Acceptor Complex-Driven Divergent Routes to α-Amino Bicyclopentyl Iodides and Methylene Cyclobutanols.

Amines are essential due to their structural diversity and biological significance. Introducing the valuable bicyclopentane (BCP) moiety at the α-position of amines offers a promising strategy for developing novel bioactive compounds. This study outlines a divergent synthesis approach to generate α-amino-functionalized bicyclopentyl iodides and methylene cyclobutanols under mild and environmentally sustainable conditions.

Visible-Light Driven Synthesis of Vinyl Amines without Photocatalyst.

We developed a visible-light-induced vinyl amination of activated alkenes using TMSN and CsF through EDA complex formation under an oxygen atmosphere. Without light, the EDA complex forms between activated alkene, CsF, and oxygen. Upon exposure to light, oxygen in the complex gets excited, initiating the HAT process.

Triple Catalysis for the Tandem Transformation of Cyclopropyl Ketones to SCF-Substituted Dihydrofurans.

In this study, we have developed an effective and general strategy for synthesizing various 4-[(trifluoromethyl)thio]-2,3-dihydrofuran derivatives with high regioselectivity from easily prepared cyclopropyl ketone under mild reaction conditions. By the combination of photoredox, copper, and Lewis acid catalysis into a triple catalytic system, this methodology facilitates the selective cleavage of the carbon-carbon bonds and the formation of new carbon-oxygen and carbon-sulfur bonds. In addition, to enhance the synthetic feasibility of this protocol, we demonstrate its broad applicability across a wide range of substrates and its scalability for large-scale synthesis.

Photocatalyzed Direct C(sp)-H Alkenylation of Unactivated Alkanes via Tandem C-C Activation of Cyclopropenes.

A highly adaptable method has been developed for the alkenylation of a broad spectrum of inert alkanes, employing milder reaction conditions. Tetrabutylammonium decatungstate (TBADT) serves as a photocatalyst for hydrogen atom transfer (HAT), instigating the formation of transient alkyl radicals through C(sp)-H functionalization. These radicals exhibit regioselective addition to cyclopropenes, followed by the subsequent activation of C-C bonds, forming the corresponding vinylated derivatives.

Photoredox cross-dehydrogenative C(sp)-C(sp) coupling of heteroarenes with secondary amines through 1,5-HAT.

The functionalization of α-C(sp)-H bonds in amines has become a focal point of contemporary research. Here, we report a new approach utilizing photocatalysis α-C(sp)-H bond functionalization in alicyclic and aliphatic secondary amines facilitated by intramolecular 1,5-hydrogen atom transfer (HAT). This finding unlocks a sustainable method for rapidly constructing complex heterocyclics cross-dehydrogenative C-C coupling of protected amines and nitrogen-containing heterocycles.

Catalytic C()-H Trifluoroethylation of Amino Acids and Carboxylic Acids.

Integrating of the trifluoroethyl (-CHCF) group into the organic compounds by activating the distal C()-H bond is a challenging but crucial task in organic chemistry. This transformation imparts unique physicochemical properties to the compounds, such as enhanced lipophilicity, metabolic stability, and altered electronic characteristics. In this study, we unveil a new palladium-catalyzed method to directly introduce the trifluoroethyl group into amino acid and carboxylic acid derivatives.

Organophotoredox Catalysis: Switchable Radical Generation from Alkyl Sodium Sulfinates for Sulfonylation and Alkylative Activation of C-C Bonds of Cyclopropenes.

Generating alkyl radicals from the sulfonyl radicals remains challenging in synthetic chemistry. Here, we report an efficient photocatalyzed strategy using alkyl sodium sulfinates as both sulfonylating and alkylating reagents by controlling the reaction temperature. This methodology provides a versatile protocol for synthesizing diastereoselective sulfonylated cyclopropanes and poly-substituted styrene derivatives.

Organophotocatalyzed Mono- and Bis-Alkyl/Difluoroalkylative Thio/Selenocyanation of Alkenes.

Organophotocatalyzed three-component 1,2-difluoroacetyl/alkyl/perfluoroalkylative thio/selenocyanation of styrene derivatives under stoichiometric, transition metal-, oxidant-, and additive-free, and mild redox-neutral conditions is reported. Organophotocatalyst 4CzIPN operates the overall radical-polar-crossover mechanistic cycle via initial oxidative luminescence quenching, and the key intermediates were experimentally detected. Selective mono-alkylative thiocyanation of alkenes using dibromoalkanes is also demonstrated.

Metal and catalyst-free strategy to access 1,3-thio-heteroaryl BCP derivatives.

The widespread presence of bicyclo[1.1.1]pentane (BCP) and sulfur motifs in pharmaceutical compounds underscores the significance of synthesizing suitably functionalized BCP thioethers.

An organo-photocatalyzed visible-light-driven multi-component approach for carbothioaryl/alkylation of activated alkenes C(sp)-H bond functionalization.

A visible-light-driven organophotocatalyzed multi-component approach for carbothiolation of activated alkenes is demonstrated under environmentally benign and redox-neutral conditions, involving direct C(sp)-H functionalization followed by electrophilic alkyl/arylthiolation. The three-component difunctionalization reaction is a complete transition-metal and peroxide-free process conducted under milder conditions. In this composite reaction, by employing bench-stable reagents, the formation of two new C(sp)-C(sp) and C(sp)-S bonds is achieved for a wide variety of substrates, showcasing the excellent functional group tolerance and chemoselectivity of the methodology.

Palladium-Catalyzed Direct C(sp)-H Cyanomethylation of Arylamides using Chloroacetonitrile.

In this study, we devised a palladium-catalyzed efficient and versatile method for C(sp)-H -cyanomethylation of arylamides with a broad substrate scope and moderate to excellent yields. An inexpensive and commercially available chloroacetonitrile was employed as a cyanomethylating source. This method is also compatible with the air atmosphere.

Metal-Free Photoredox Four-Component Strategy to 1,3-Functionalized BCP Derivatives.

Trifluoromethyl bicyclo[1.1.1]pentanes (BCPs) have attracted significant attention from the scientific community and pharmaceutical industries due to their advantageous physicochemical properties as arene bioisosteres.

Photoinduced Cascade Difluoroalkylative Ring-Opening of Vinyl Cyclopropanes.

Here, we report a facile and efficient method for the difluoroalkylation of vinyl cyclopropanes (VCPs) using visible-light organophotoredox catalysis. This strategy exploits the interplay of α-amino alkyl radical-mediated halogen-atom transfer (XAT) reaction. The broad substrate scope, excellent functional group compatibility, operational simplicity, inexpensive CF precursors, and high efficiency make this protocol promising for the cost-efficient synthesis of allylic difluoroalkylated derivatives.

Diastereoselective palladium-catalyzed C(sp)-H cyanomethylation of amino acid and carboxylic acid derivatives.

In this study, we report an efficient protocol for Pd-catalyzed methylene β-C(sp)-H cyanomethylation of 8-aminoquinoline-directed α-amino acids using inexpensive chloroacetonitrile. Iodoacetonitrile generated from chloroacetonitrile reacts with methylene C(sp)-H bonds of α-amino acids with excellent diastereoselectivity, enabling access to a wide range of important γ-cyano-α-amino acids. Our protocol works well with different amino acid and carboxylic acid derivatives with good chemical yields and high functional group tolerance.

Visible-Light-Driven Organophotocatalyzed Multicomponent Approach for Tandem C(sp)-H Activation and Alkylation Followed by Trifluoromethylthiolation.

A visible-light-driven organophotocatalyzed multicomponent approach has been developed for tandem direct C(sp)-H activation and alkylation followed by trifluoromethylthiolation in a one-pot operation. We report a completely metal-free, tandem, three-component approach for the difunctionalization of activated alkenes via the photoinduced radical pathway. This protocol allows the formation of two new C(sp)-C(sp) and C(sp)-SCF bonds using a bench-stable, easy-to-handle trifluoromethylthiolating reagent under mild reaction conditions.

TEMPO-Mediated Selective Synthesis of Isoxazolines, 5-Hydroxy-2-isoxazolines, and Isoxazoles via Aliphatic δ-C(sp3)-H Bond Oxidation of Oximes.

Selective synthesis of three different bioactive heterocycles; isoxazolines, 5-hydroxy-2-isoxazolines and isoxazoles from the same starting material using TEMPO (2,2,6,6-Tetramethylpiperidin-1-oxyl) as a radical initiator is reported. Selectivity was achieved using different oxidants with TEMPO. The reaction goes through a 1,5-HAT (hydrogen atom transfer) process resulting in products with good yields.

Tetrathiomolybdate and Tetraselenotungstate as Sulfur/Selenium Transfer Reagents: Applications in the Synthesis of New Thio/Seleno Sugars.

Sulfur and selenium containing sugars have gained prominence in the last two decades because of their importance in several biological applications. These type of carbohydrate scaffolds are also challenging targets for synthesis. In this personal note, we have summarised the results of our investigation over the last 20 years on the use of two reagents, benzyltriethylammonium tetrathiomolybdate and tetraethylammonium tetraselenotungstate, in efficient transfer of sulfur and selenium respectively to the synthesis of a number of carbohydrate derivatives.

Visible-Light-Driven Organophotocatalyzed Mono-, Di-, and Tri-C(sp)-H Alkylation of Phosphoramides.

A photocatalytic metal-free, visible-light-driven, highly atom-economic, direct multiple α-C(sp)-H alkylation of phosphoramides and thiophosphoramides is demonstrated under environmentally benign conditions. Economically viable and commercially available Eosin-Y is used as an HAT photocatalyst for mono-α-C(sp)-H alkylation of phosphoramide derivatives. Remarkably, di- and tri-C(sp)-H alkylation of phosphoramides and thiophosphoramides using an acridinium photocatalyst is reported with good yield and selectivity.

Ammonium Chloride-Mediated Trifluoromethylthiolation of -Quinone Methides.

Ammonium chloride-mediated trifluoromethylthiolation of -quinone methides is reported using inexpensive and bench stable AgSCF as a nucleophilic trifluoromethylthiolating (-SCF) reagent. This method is an efficient strategy for the construction of the benzylic C(sp)-SCF bond to synthesize trifluoromethylthio-diarylmethane derivatives by 1,6-conjugate addition/aromatization under mild reaction conditions without any metal catalyst, oxidants, or additives. This is the first report of trifluoromethylthiolation of -quinone methides.

Metal-Free Visible-Light-Promoted Trifluoromethylation of Vinylcyclopropanes Using Pyrylium Salt as a Photoredox Catalyst.

Visible-light-induced metal-free trifluoromethylation of activated, carbocyclic, and unactivated vinylcyclopropanes via a ring-opening reaction using the Langlois reagent (CFSONa) is reported to synthesize allylic trifluoromethylated derivatives. Allylic trifluoromethylation was achieved by a photo-oxidative single electron transfer (SET) process at an ambient temperature and under metal-free conditions and visible-light irradiation using pyrylium salt as a photoredox catalyst. The reported methodology has an operational simplicity, broad substrate scope, high functional group tolerance, and scalability.