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.

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.

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.

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.

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.

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.

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.