The 50 most-cited articles in Organic Letters, 2024

Saturated bicyclic amines are increasingly targeted to the pharmaceutical industry as sp 3 -rich bioisosteres of anilines. Numerous strategies have been established for the preparation of bridgehead aminobicyclics. However, methods to assemble the bridge-amino hydrocarbon skeleton, which serves as a meta -substituted arene bioisostere, are limited. Herein, a general approach to access 2-aminobicyclo[2.1.1]hexanes (aminoBCHs) by titanium-catalyzed formal [2π + 2σ] cycloaddition of bicyclo[1.1.0]butanes and 2-azadienes was developed. Simple derivatization of aminoBCHs leads to various medicinally and agrochemically important analogues.

A palladium-catalyzed divergent cascade decarboxylative annulation of aryl iodides and α-oxocarboxylic acids using norbornene (NBE) derivatives as a controlled switch is reported. When NBE is used as a mediator, fluorenones are synthesized with moderate to excellent yields via a Catellani reaction that involves sequential ortho -C–H arylation and ipso -decarboxylative acylation of aryl iodides. Employing oxanorbornadiene (ONBD) instead of NBE enables the assembly of dibenzo[ a, c ]cycloheptenones by a retro-Diels–Alder reaction rather than the release of an ONBD. Additionally, the synthetic utility of this method is demonstrated by the diversification of the products.

= 5 and 6) cycloaddition of bicyclo[1.1.0]butanes (BCBs) with imidazolidines/hexahydropyrimidines is described. The reaction provides a modular, atom-economical, and efficient strategy to two libraries of synthetically challenging medium-bridged rings, 2,5-diazabicyclo[5.1.1]nonanes and 2,6-diazabicyclo[6.1.1]decanes, in moderate to excellent yields. This reaction also features simple operation, mild reaction conditions, and broad substrate scope. A scale-up experiment and various synthetic transformations of products further highlight the synthetic utility.

We have developed an unprecedented electron-donor-controlled divergent reaction between N -alkylsulfonylated acrylamides and Br–R F, facilitated by an electron donor–acceptor (EDA) complex, for the synthesis of fluorine-containing oxindoles and amides. Key to this divergent transformation is the EDA complex generation by altering electron donors. This approach has several advantages, such as broad substrate scope, being metal-catalyst- and photocatalyst-free, and having good functional group tolerance.

A visible-light-induced radical alkylarylation of N -aryl bicyclobutyl amides with α-carbonyl alkyl bromides for the synthesis of functionalized 3-spirocyclobutyl oxindoles is described in which β-selective radical addition of the alkyl radical to N -aryl bicyclobutyl amides forms a key radical intermediate followed by interception with intrinsic arene functional group. This approach can be applicable to a wide range of α-carbonyl alkyl bromides, including primary, secondary, and tertiary α-bromoalkyl esters, ketones, nitriles, and nitro compounds.

The electron donor–acceptor (EDA) complexes have been extensively studied, which formed an electronically excited state, obviating the need for an exogenous photocatalyst. Herein, we report a mild and efficient strategy for photoinduced radical domino perfluoroalkylation/cyclization using N, N, N ′, N ′-tetramethylethane-1,2-diamine (TMEDA) as an electron donor. This protocol could be well expanded to access various polycyclic quinazolinones containing perfluoroalkyl groups, exhibiting photocatalyst-free, good functional group tolerance, and environmentally friendly features.

Reactions that change the identity of an atom within a ring system are emerging as valuable tools for the site-selective editing of molecular structures. Herein, we describe the expansion of an underdeveloped transformation that directly converts azaarene-derived N -oxides to all-carbon arenes. This ring transmutation exhibits good functional group tolerance and replaces the N -oxide moiety with either unsubstituted, substituted, or isotopically labeled carbon atoms in a single laboratory operation.

The difunctionalization of alkenes using aryl thianthrenium salts as the aryl sources has been reported sporadically. However, the four-component difunctionalization of alkenes on the basis of aryl thianthrenium salts has not been reported thus far and still remains a challenge. Herein, a visible light/copper catalysis-enabled four-component reaction of aryl thianthrenium salts, DABCO·(SO 2 ) 2, alkenes, and TMSN 3 is presented, which affords a facile approach to β-azidosulfones in good yields with broad substrate scope and excellent functional group tolerance. This strategy indirectly realizes the method for the synthesis of β-azidosulfones through site-selective aryl C–H bond functionalization and alkene difunctionalization. This developed method is an important complement to thianthrenium salts chemistry.

Despite the significant success of decarboxylative radical reactions, the catalytic systems vary considerably upon different radical acceptors, requiring renewed case-by-case reaction optimization. Herein, we developed an iron catalytic condition that enables the highly efficient decarboxylation of various carboxylic acids for a range of radical transformations. This operationally simple protocol was amenable to a wide array of radical acceptors, delivering structurally diverse oxime ethers, alkenylation, alkynylation, thiolation, and amidation products in useful to excellent yields (>40 examples, up to 95% yield).

Photoexcitation electron donor-acceptor (EDA) complexes provide an effective approach to produce radicals under mild conditions, while the catalytic version of EDA complex photoactivation remains scarce. Herein, we report a visible-light-induced organophotocatalytic pathway for the cyanoalkylation of azauracils using inexpensive and readily available 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalytic electron donor. This synthetic method exhibits exceptional compatibility with various functional groups and presents 34 examples in high yields. The efficient cyanoalkylation offers an environmentally friendly and sustainable route toward enhancing the structural and functional diversity of azauracils.

A green and sustainable electrochemical oxidative cyclization of enaminones with thioamides under metal- and oxidant-free conditions has been developed, providing an efficient approach for thiazole synthesis. Furthermore, 1,2,4-thiadiazoles can be selectively accessed via the electrochemical dimerization of thioamides in the absence of enaminones.

Spirocyclobutyl oxindoles have garnered substantial attention in drug discovery and pharmaceuticals owing to their wide range of biological activities. Strain-release in small-ring compounds is a powerful strategy to enable efficient access to complex molecules. In this study, we successfully realized a photoredox-catalyzed strain-release radical spirocyclization approach to attain functionalized spirocyclobutyl oxindoles. A diverse array of radicals, such as sulfonyl, phosphonyl, and trifluoromethyl, were added efficiently to the strained C-C σ-bond of bicyclobutanes (BCBs) to afford a library of spirocyclobutyl oxindoles. Furthermore, the obtained products could be transformed into valuable building blocks. The observed reactivity and selectivity have been rationalized based on density functional theory calculations.

Because of environmental and health impacts, there is an ongoing necessity to develop sustainable primary explosives to replace existing lead-based analogues. Now we describe a potential primary explosive, dipotassium 4,6-dinitro-5,7-dioxidobenzo[c][1,2,5]oxadiazole 1-oxide (K 2 DNDP), which exhibits an excellent thermal stability ( T dec = 281 °C), positive oxygen balance (+4.79%), and a calculated crystal density of ρ = 2.274 g cm –3 at 100 K. Its physicochemical properties concomitantly with its straightforward synthesis make it a potential replacement for lead-based initiators.

A visible-light-induced photoredox three-component carbocyclization reaction of 1,7-enynes with sulfoxonium ylides and water is reported. The protocol provides a facile entry to structurally valuable highly functionalized cyclopenta[ c ]quinoline scaffolds in a highly chemoselective and stereoselective manner. Salient features of this method include facile redox-neutral conditions, no requirement of base or other additive, and good functional-group tolerance.

A green and highly efficient visible-light-induced radical cascade difluoroalkylation/cyclization reaction of N -cyanamide alkenes has been developed. A variety of CF 2 COR-containing quinazolinones have been obtained in high yields with cheap non-metallic 4CzIPN as the photocatalyst. This photocatalytic reaction provides rapid, facile, and practical access to valuable polycyclic quinazolinone, and it is amenable to the gram scale.

A three-component cascade reaction involving cyclohexanones, anilines, and diaryl diselenides under metal-free conditions is reported. The ortho-selenation of cyclohexanones with diaryl diselenides, followed by sequential dehydroaromatization with anilines, enables the preparation of a variety of o -selanyl anilines in moderate to excellent yields. This innovative transformation is notable for its excellent tolerance of functional groups and is suitable for the late-stage modification of complex pharmaceuticals.

Organic sulfones are an important class of chemical compounds widely used in many research fields. The direct decarboxylative sulfonylation of carboxylic acids is attractive but challenging, particularly when iron is used as a metal catalyst. Herein, we describe a photoinduced iron-catalytic method for the synthesis of sulfones directly using carboxylic acids via a radical-based decarboxylation. This protocol is mild, highly efficient, and easy-to-operate. A broad scope of carboxylic acids and carbon electrophiles could be well tolerated. A mechanism involving the iron-catalyzed decarboxylation, radical transfer, single-electron reduction, and nucleophilic attack is proposed.

Rapid and efficient construction of multifunctionalized skeletons through a one-pot multicompound domino reaction has been recognized as a simple and practical strategy. Herein, a visible-light-enabled three-component reaction of isothiocyanates, isocyanides, and thianthrenium salt-functionalized arenes is presented, which affords a facile approach to sulfur-containing trisubstituted imidazoles in good yields with a broad substrate scope and excellent functional group tolerance. The byproduct thianthrene is recovered in quantity, thereby ultimately reducing the production of chemical waste. The developed methodology has potential value for the discovery and development of thioimidazole-based drugs.

Presented herein is a novel synthesis of pharmaceutically privileged spiroindoline derivatives via cascade reactions of N -methyl- N -nitrosoanilines with diazo homophthalimides. A group of mechanistic studies disclosed that the formation of product involves an unusual reaction mode of N -methyl- N -nitrosoaniline featuring an initial C(sp 2 )–H bond activation/alkylation followed by a C(sp 3 )–H bond activation/spiroannulation. To our knowledge, this is the first example in which N -methyl- N -nitrosoaniline acts as a C3N1 synthon to accomplish formal [4+1] spiroannulation with the participation of the N -methyl unit rather than the previously reported C2N1 synthon to undergo formal [3+2] annulation without the participation of the N -methyl unit. In general, this newly developed synthetic protocol features simple and readily accessible starting materials, valuable products, unique reaction mechanism, high efficiency and atom-economy, excellent compatibility with diverse functional groups, and ready scalability.

In the presence of a thiyl radical species, the catalytic Markovnikov thiol–ene reaction is challenging because it prefers to proceed via a radical pathway, thereby leading to anti -Markovnikov selectivity. In this work, a rare example of thiyl radical engaged in Markovnikov thiol–ene reaction enabled by cobalt catalysis is reported. This protocol features the avoidance of unique oxidants, exclusive regioselectivity, and broad substrate scope. Scalable synthesis and late-stage modification of complex molecules demonstrate the practicability of the protocol.

The photocatalyzed radical-triggered thio/selenosulfonylation–bicyclization of indole-tethered 1,6-enynes has been established for the first time, enabling the synthesis of various previously unreported thio/selenosulfonylated benzo[ c ]pyrrolo[1,2,3- lm ]carbazoles with moderate to good yields under mild conditions. The reaction pathway was proposed, consisting of energy transfer, homolytic cleavage, radical addition, 5- exo - dig, radical coupling, and a Mallory reaction cascade. This approach exhibits a wide substrate compatibility and excellent tolerability toward various functional groups and is characterized by its remarkable efficiency in both bond formation and annulation.

We disclose N ′-arylidene- N -acryloyltosylhydrazides as novel skeletons for the synthesis of biologically relevant alkylated pyrazolones through a photoinduced radical cascade with N -(acyloxy)pthalimides as readily available alkyl surrogates. The reaction proceeds through the formation of a photoactivated electron donor–acceptor (EDA) complex between alkyl N -(acyloxy)phthalimide (NHPI) esters and LiI/PPh 3 as a commercially available donor system. The reaction exhibits a broad scope and scalability, thereby enabling synthesis of a broad spectrum of functionally orchestrated alkylated pyrazolones under mild and transition-metal-free conditions.

Herein, we present a transition-metal-free, easy handling protocol for regioselective carboxylation of gem -difluorostyrenes with sodium formate as the C1 source. 30 examples of α-fluoracrylates were obtained in yields of 30 to 80% under these conditions. A defluorinative monofluorovinyl intermediate and consecutive photoinduced electron transfer mechanism were proposed after mechanism investigation.

Disclosed here is a visible-light photoredox-catalyzed intermolecular sequential α-aminomethyl/carboxylative dearomatization of indoles with CO 2 and α-aminoalkyl radical precursors, affording a series of functionalized indoline-3-carboxylic acids and lactams in good yields with high regioselectivity. This multicomponent reaction provides a green and facile method for the synthesis of diverse functionalized indolines by using CO 2 as the carboxylic and carbonyl source.

We disclose herein a photocatalytic radical cascade cyclization of diazoalkanes for the divergent synthesis of important carbocycles and heterocycles. Under the optimal reaction conditions, various indanone, pyrone, and pyridinone derivatives can be obtained in moderate to good yields. Mechanistic experiments support the formation of carbon-centered radicals from diazoalkanes through the proton-coupled electron transfer process. Scale-up reaction using continuous flow technology and useful downstream application of the formed heterocycles further render the strategy attractive and valuable.

Bicyclo[1.1.1]pentane (BCP) heteroaryls make up an important class of BCP derivatives in drug discovery. Herein, we report the visible-light-mediated synthesis of cyanoisopropyl BCP-heteroaryls motifs from N -containing heterocycles, [1.1.1]propellane, and AIBN (2,2′-azobis(isobutyronitrile)) through three-component cascade reaction. Importantly, this protocol is compatible with pyrazinones, quinoxaline-2( 1H )-one, azauracils, quinoline derivatives, and imidazo[1,2- b ]pyridazine, as well as various phenyl disulfide derivatives; thus, this operationally simple and general methodology could enable rapid library generation of sought-after BCP derivatives for drug development.

The use of readily available and diverse sulfamoyl chlorides for synthesizing sulfonamide compounds presents an intriguing, yet significantly underexplored strategy. Activating sulfamoyl chlorides via single-electron reduction poses challenges due to their high reduction potential. Alternatively, the SO 2 –Cl bond in sulfamoyl chlorides could be readily cleaved by XAT. However, the existing methodologies have been limited to either the use of photocatalyst or the monofunctionalization of activated alkenes. Here, we report a regioselective sulfamoyl-oximation of alkenes by involving the activation of sulfamoyl chlorides through a HAT and XAT relay strategy in a photocatalyst-free way. The key to this success lies in the dual roles of tert -butyl nitrite (TBN), which not only serves as the source of oximes but also acts as the HAT reagent to generate the crucial XAT reactive species. The exclusion of metal catalysts or photosensitizers for utilizing light energy renders this protocol versatile and universally applicable for synthesizing a broad range of structurally diverse…

A visible light-promoted aromatization-driven deconstructive fluorination of spiro carbocycles is presented. A series of spiro dihydroquinazolinones reacted efficiently with NFSI under visible light irradiation to afford the 2-(4-fluoroalkyl)quinazolin-4(3 H )-ones in good yields with excellent functional group tolerance. A radical pathway involving C–C bond cleavage and F atom transfer is proposed for the reaction. In addition, the ring-opening chlorination of spiro dihydroquinazolinones with NCS was also applicable.

Presented herein is an atom- and step-economical method enabling the precise assembly of a heptacyclic scaffold containing both azocine and indoline units through the cascade reactions of indolin-1-yl(aryl)methanimines with diazo indanediones. The formation of products involves C-H bond activation and double carbene insertion followed by intramolecular condensation, retro-[2 + 2] cycloaddition, and recyclization. This cascade reaction not only provided a concise and straightforward strategy for the synthesis of the otherwise difficult to obtain heptacyclic compounds from readily available substrates but also disclosed an unprecedented reaction mode for indoline derivatives and diazo compounds. In general, this novel synthetic protocol has advantages, such as easily obtainable substrates, structurally sophisticated products, concise synthetic procedure, good compatibility with diverse functional groups, and ready scalability. Moreover, the products thus obtained showed decent antiproliferative activity against three human cancer cell lines.

An N-heterocyclic carbene (NHC)-catalyzed atroposelective macrolactonization has been disclosed. This approach affords planar-chiral macrocycles in high yields with excellent enantioselectivities over a broad substrate scope. Controlled experiments suggest that the enantioselectivity might arise from the cation– n interaction between the acyl azolium and the electron-rich moiety in the substrate. This mechanism is supported by density functional theory calculations, which also suggest an important π–π interaction in stabilizing the transition state.

We report here a step-economic and cost-effective cross-electrophile coupling of aryl thianthrenium salts with widely available aryl bromides, which proceeded effectively via C-S bond activation at ambient temperature in THF in the presence of a palladium catalyst, magnesium turnings, and lithium chloride to enable the facile assembly of a wide array of structurally diverse biaryls in modest to good yields with good functional group compatibility. In addition, the gram-scale reaction could also be realized.

Operationally simple and generally applicable arene nitration with cheap and easily accessible chemicals has been a long-sought transformation in the synthetic organic community. In this work, we realized this goal with nontoxic and inexpensive Fe(NO 3 ) 3 ·9H 2 O as the nitro source and easily recyclable solvent hexafluoroisopropanol as the promotor via a network of hydrogen-bonding interactions. As a result of the relative mildness and high reliability of this protocol, late-stage nitration of various highly functionalized natural products and commercially available drugs was realized.

Herein, we present a novel Catellani-type reaction that employed aryl-thianthrenium salts as aryl substrates to trigger the subsequent palladium/norbornene cooperatively catalyzed progress. This strategy can achieve site-selective C-H difunctionalization of aryl compounds without directing groups or a known initiating reagent. A series of functionalized syntheses of bioactive molecules further demonstrated the potential of this strategy.

Herein, a palladium-catalyzed bicycloaromatization of o -(alkynyl)styrenes with alkynes is reported. In this protocol, the 6- endo - dig cyclization of o -(alkynyl)styrenes is followed by deprotonation to complete the first cycloaromatization, and then, a regioselective alkyne insertion/C–H activation occurs to achieve the second cycloaromatization, resulting in atom- and step-economical syntheses of polysubstituted chrysenes. Notably, the products can be further used to construct π-extended arenes using the Scholl reaction.

An iron-catalyzed photochemical sulfinamidation of hydrocarbons with N -sulfinylamines has been developed. The merger of ligand-to-metal charge transfer (LMCT) of FeCl 3 with hydrogen atom transfer (HAT) process is the key for the generation of alkyl radicals from hydrocarbons, and the resultant alkyl radicals were readily trapped by N -sulfinylamines to produce structurally diverse sulfinamides. Contrary to traditional methods that inevitably use sensitive organometallic reagents and prefunctionalized substrates, our approach features simple operation and the wide availability of starting materials. Gratifyingly, the reaction is scalable, and the obtained sulfinamides can be conveniently converted to highly functionalized sulfur(VI) derivatives.

This work demonstrates the synthesis of a variety of perfluoroalkyl heterocycles via a visible-light-driven radical-polar crossover cyclization strategy. In this process, single-electron reduction/S N V-type/cyclization sequences follow the radical addition reaction of a diazoester, which differs from the current role of diazoesters as radical precursors/acceptors. This transformation demonstrates excellent functional group compatibility and allows for the modification of many bioactive molecules with diazoesters. Such a reaction could represent a novel approach to the photochemical transformation of diazo compounds.

Utilizing energy transfer catalysis, this research employed the bifunctional reagents benzotriazole carboxylic acid oxime esters to simultaneously generate benzotriazole and imine radicals. The synthesis of two distinct C-N bonds in a single conversion is showcased through radical addition and radical-radical cross-coupling processes between benzotriazole carboxylic acid oxime ester and olefins. This process facilitates the intermolecular two-component unsymmetrical diamination reaction of olefins. Using this approach, more than 40 benzotriazole-containing molecules were successfully synthesized using styrene, indole, and benzofuran as acceptors, with yields ranging from moderate to excellent.

With the flourishing progress of ligand-to-metal charge transfer (LMCT) photocatalysis, various metals were developed as catalysts to activate abundant alkane feedstocks for the synthesis of functionalized organic compounds. However, to the best of our knowledge, most of the LMCT catalysts are difficult to recover and reuse for the next cycles. Herein, we report a reusable Lewis acidic ionic liquid (LAIL)-catalyzed radical-cascade alkylation/cyclization of N -alkyl- N -methacryloyl benzamides with unactivated alkanes for the synthesis of alkylated isoquinoline-1,3-(2 H,4 H )-diketones. The protocol features mild reaction conditions, high atom utilization efficiency, scale-up synthesis, simple operation, and recycling of catalysts.

Presented herein is a novel synthesis of indenone-fused pyran derivatives via the cascade reactions of aryl enaminones with cyclopropenones. The formation of products involves a one-pot cascade procedure consisting of aryl C–H bond and enamine C–H bond functionalization along with C–C bond cleavage of cyclopropenone and 1,3-rearrangement of the in situ-formed allylic alcohol moiety followed by intramolecular O-nucleophilic addition and Me 2 NH elimination. To our knowledge, this is the first synthesis of indenone-fused pyran derivatives via simultaneous formation of both indenone and pyran scaffolds through concurrent unsymmetrical relay C–H bond activation and double C–C/C–O bond formation. Moreover, the usefulness of this method is further showcased by its suitability for large-scale synthetic scenarios and diverse transformations of products.

Light-mediated Halogen-Atom Transfer (XAT) has become a significant methodology in contemporary synthesis. Unlike α-aminoalkyl and silyl radicals, ligated boryl radicals (LBRs) have not been extensively explored as halogen atom abstractors. In this study, we introduce NHC-ligated boranes as optimal radical chain carriers for the intermolecular reductive radical hydroalkylation and hydroarylation of electron-deficient olefins by using direct UV-A light irradiation. DFT analysis allowed us to rationalize the critical role of the NHC ligand in facilitating efficient chain propagation.

The nickel/photoredox dual catalysis system is an efficient conversion platform for the difunctionalization of unsaturated hydrocarbons. Herein, we disclose the first dual nickel/photoredox-catalyzed intramolecular 1,2-arylsulfonylation of allenes, which can accurately construct a C(sp 2 )–C(sp 2 ) bond and a C(sp 3 )–S bond. The reaction exhibits excellent chemoselectivity and regioselectivity, allowing modular conformations of a diverse series of 3-sulfonylmethylbenzofuran derivatives. Control experiments showed that the bipyridine ligand is crucial for the formation of a stable σ -alkyl nickel intermediate, providing the possibility for sulfonyl radical insertion. Meanwhile, the electrophilic sulfonyl radical facilitates further oxidative addition of the σ -alkyl nickel intermediate and inhibits addition with allenes. In addition, control experiments, cyclic voltammetry tests, Stern–Volmer experiments, and density functional theory calculations afford evidence for the Ni(0)/Ni(I)/Ni(II)/Ni(III) pathway in this 1,2-arylsulfonylation.

causes the decarboxylation of 5-vinyloxazolidine-2,4-diones to generate amide-containing aza-π-allylpalladium 1,3-dipole intermediates, which are capable of triggering the dearomatization of 3-nitroindoles for diastereo- and enantioselective [3+2] cycloaddition, leading to the formation of a series of highly functionalized pyrroloindolines containing three contiguous stereogenic centers with excellent results (up to 99% yield, 88:12 dr, and 96% ee).

1-(2-(Arylethynyl)benzoyl)indoles were developed as an innovative scaffold for radical cascade cyclization under visible-light and mild conditions, enabling efficient synthesis of sulfonated benazepino[1,2- a ]indolones. This method operates at room temperature and demonstrates broad substrate compatibility and scalability, with promising potential for sunlight-driven reactions.

Herein, we disclose a readily available phenothiazine derivative as an organocatalyst, which upon excitation with 371 nm light acquires a strongly reducing power and serves to induce the radical cascade difluoromethylation/cyclization reaction of N -homoallylacetohydrazides. A variety of CF 2 COR-tetrahydropyridazines have been obtained in moderate to excellent yields. This catalytic platform proceeds under metal-free conditions with a wide substrate scope and broad functional group compatibility, which unlocks the new reactivity of phenothiazine derivatives and adds significant synthetic value to N -heterocycles.

An unprecedented selective chromone annulation reaction controlled by solvent for the divergent synthesis of two types of 2,3-disubstituted chromone skeletons has been developed. A variety of 2-chromonyl-3-hydrazono-chromones and 2-alkoxy-3-hydrazono-chromones were constructed efficiently from readily available o -hydroxyphenylenaminones ( o -HPEs) and aryldiazonium salts at room temperature. This strategy is highly chemoselective and features mild reaction conditions, broad substrate scope, broad functional group tolerance, easy gram-scale preparation, and simple filtration to obtain the pure products without tedious column chromatography.

In this work, we have constructed three new Co(II) complexes in which steric features govern their structural geometry. The metal ligand-cooperation behavior of the alkoxy arm is utilized to explore the catalytic activities of these complexes with respect to dehydrogenation. A wide range of C-3-substituted quinoline and quinazoline derivatives were synthesized in high yields. The developed protocol's usefulness is enhanced by the chemoselective transformation of different fatty alcohols to synthesize heterocycles having distal unsaturation. Various kinetic, mechanistic, and control studies were conducted to comprehend the reaction route.

An efficient visible light/copper-enabled arylation and alkenylation of phosphorothioates with thianthrenium salts via a C(sp 2 )–S cross-coupling reaction have been demonstrated. This strategy uses aryl/alkenyl thianthrenium salts as new electrophilic reagents, which can be easily prepared by the site-selective C–H thianthrenation of arenes/alkenes with high regioselectivity. Mechanistic studies revealed a crucial role of the in situ formed copper–sulfur complex, which undergoes a facile SET process with the thianthrenium salts under visible light conditions, thereby successfully achieving the desired cross-coupling reactivity.

Here, we demonstrate palladium-catalyzed Hiyama-type cross-coupling reactions of aryl thianthrenium or phenoxathiinium salts. By employing stable and inexpensive organosilanes, the arylation, alkenylation, and alkynylation were realized in high efficiency using commercially available Pd( t Bu 3 P) 2 as the catalyst, thus providing a reliable method for preparation of biaryls, styrenes, and aryl acetylenes with a broad functional group tolerance under mild conditions. Given the accessibility of aryl thianthrenium or phenoxathiinium salts from simple arenes in a remarkable regioselective fashion, this protocol also provides an attractive approach for the late-stage modification of complex bioactive scaffolds.

An efficient synthesis of quinoxaline-fused aza-bicyclo[2.1.1]hexanes bearing multiple quaternary carbon centers via the intermolecular [2π+2σ] cycloaddition of bicyclo[1.1.0]butanes and quinoxalin-2(1 H )-ones, facilitated by Lewis acid catalysis, is presented. This reaction is carried out under mild conditions and exhibits a broad substrate scope and excellent functional group tolerance.

An efficient palladium-catalyzed region-selective C7-trifluoromethylation of indolines using commercially available Umemoto’s reagent was reported. The reaction utilizing Umemoto’s reagent as CF 3 radical precursor, pyrimidine as a removable directing group, Pd(II) as a catalyst, and Cu(II) as an oxidant furnished the required products with excellent regioselectivities and good yields. The present strategy has good region-selectivity, broad substrate scope, and scale-up application. Additionally, the present method was underlined by the direct C-1 trifluoromethylation of carbazoles. Furthermore, C7 trifluoromethylated indole can also be easily obtained via Pd-catalyzed direct C-7 trifluoromethylation/oxidation/deprotection sequential reactions.