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Of the methods for direct fluorination of unactivated C(sp

A gold-catalyzed synthesis of tetrasubstituted 1,3-enynes from hypervalent iodine(III) reagents and activated alkenes is reported. This reaction involves an in situ formed alkynyl Au(III) species and a subsequent direct C(sp2)-H functionalization of alkenes, offering 26 enynes in 62-92% yield with excellent functional group tolerance.

Oxazol-2(3H)-ones play a significant role in the fields of organic synthesis and drug development. The classical synthesis of oxazol-2(3H)-one derivatives requires high temperatures, metal catalysts, complex substrates or multi-step reactions. We report a concise synthesis of oxazol-2(3H)-ones from readily available diazo compounds and sulfilimines through a tandem rearrangement/aziridination/ring-expansion reaction in the absence of any catalyst and additive. This reaction is scalable and the obtained products were readily converted to other valuable aza-heterocyclic frameworks.

A gold-catalysed cascade C(sp3)–H alkynylation/oxy-alkynylation of acceptor-substituted carbonyl compounds with hypervalent iodine(III) reagents for the synthesis of tetra-substituted furans is described. This reaction involves two Au(I)/Au(III) catalytic cycles and proceeds through a C(sp3)–H alkynylation of a substituted ketone and a subsequent oxy-alkynylation of the generated 2-alkynyl ketone. This mild and simple method can tolerate a wide range of functionalities, offering distinct advantages over previous methods using PIDA as the external oxidant. Furthermore, a gram-scale synthesis is feasible and the synthesized furan product was readily transformed into other related compounds.

α-Amino radicals from simple tertiary amines were employed as halogen atom transfer (XAT) agents in metallaphotoredox catalysis for cross-electrophile couplings of organic bromides with organic iodides. This XAT strategy proved to be efficient for the generation of carbon radicals from a range of partners (alkyl, aryl, alkenyl, and alkynyl iodides). The reactivities of these radical intermediates were captured by nickel catalysis with organobromides including aryl, heteroaryl, alkenyl, and alkyl bromides, enabling six diverse C−C bond formations. Classic named reactions including Negishi, Suzuki, Heck, and Sonogashira reactions were readily achieved in a net-reductive fashion under mild conditions. More importantly, the cross coupling was viable with either organic bromide or iodide as limiting reactant based on the availability of substrates, which is beneficial to the late-stage functionalization of complex molecules. The scalability of this method in batch and flow was investigated, further demonstrating its applicability.

While direct nitrene insertions into C−H bonds have become an important tool for building C−N bonds in modern organic chemistry, the generation of nitrene intermediates always requires transition metals, high temperatures, ultraviolet or laser light. We report a mild synthesis of carbazoles and related building blocks through a visible light‐induced intramolecular C−H amination reaction. A striking advantage of this new method is the use of more reactive aryl sulfilimines instead of the corresponding hazardous azides. Different catalysts and divergent light sources were tested. The reaction scope is broad and the product yield is generally high. An efficient gram‐scale synthesis of Clausine C demonstrates the applicability and scalability of this new method., A new method for the synthesis of carbazoles and related compounds has been reported through either visible light irradiation or rhodium catalysis. Sulfilimines were employed as a safe nitrene source. Compared with aryl azides, aryl sulfilimines are more reactive and thus can be used under milder reaction conditions. The gram‐scale synthesis of Clausine C demonstrated the synthetic potential of this method.

Catalytic approaches to pharmaceutically important bioactive skeletons through gold carbene intermediates have experienced a dramatic development in the last decade. Although various carbene precursors continue to play an important role in heterocyclic syntheses, these reagents are associated with some drawbacks in terms of functional group tolerance, synthetic methods and safety limitations. A new generation of nitrene transfer reagents was established in 2019: the sulfilimines. These are safe, inexpensive and readily available. They can conveniently be stored and handled, and thus represent ideal reagents for the fast and modular modification of scaffolds and the preparation of libraries by intermolecular reactions of two components. Both the practical methods for synthesizing sulfilimines and the versatility of these ylidic species in gold‐catalyzed preparation of structural diversity, for both heterocycles and carbocycles, will be outlined in this Concept article., Sulfilimines, a new generation nitrene transfer reagent: The concise and scalable methods for preparing differently substituted sulfilimines are discussed. The gold‐catalyzed syntheses of diverse nitrogen‐containing compounds from these aza‐sulfur ylides through α‐imino gold carbene intermediates are summarized.

Of the methods for direct fluorination of unactivated C(sp3)–H bonds, photosensitization of SelectFluor is a promising approach. Although many substrates can be activated with photosensitizing catalysts, issues remain that hamper fluorination of complex molecules. Alcohol- or amine-containing functional groups are not tolerated, fluorination regioselectivity follows factors endogenous to the substrate and cannot be influenced by the catalyst, and reactions are highly air-sensitive. We report that benzoyl groups serve as highly efficient photosensitizers which, in combination with SelectFluor, enable visible light-powered direct fluorination of unactivated C(sp3)–H bonds. Compared to previous photosensitizer architectures, the benzoyls have versatility to function both (i) as a photosensitizing catalyst for simple substrate fluorinations and (ii) as photosensitizing auxiliaries for complex molecule fluorinations that are easily installed and removed without compromising yield. Our auxiliary approach (i) substantially decreases the reaction's induction period, (ii) enables C(sp3)–H fluorination of many substrates that fail under catalytic conditions, (iii) increases kinetic reproducibility, and (iv) promotes reactions to higher yields, in shorter times, on multigram scales, and even under air. Observations and mechanistic studies suggest an intimate ‘assembly’ of auxiliary and SelectFluor prior/after photoexcitation. The auxiliary allows other EnT photochemistry under air. Examples show how auxiliary placement proximally directs regioselectivity, where previous methods are substrate-directed.

A gold-catalyzed formal 1,3-dipolar [3 + 2] annulation using readily accessible N-acyl sulfilimines and ynamides is reported. This reaction includes the cleavage of a N-S bond and subsequent C-O bond formation. In total, 30 oxazole derivatives bearing diverse functionalities could be prepared in 43-98% yield from the corresponding sulfilimines and ynamides.

We herein report the unprecedented synthesis of diverse biologically important aza-heterocycles by employing sulfilimines as nitrene transfer reagents. This class of sulfur-based aza-ylides had not been successfully used for gold nitrene transfer before. This work contains an efficient generation of α-imino gold carbenes by N-S cleavage of sulfilimines. These gold carbenes undergo C-H insertion, cyclopropanation, and nucleophilic attack to form indoles (44 examples), 3-azabicyclo[3.1.0]hexan-2-imines (24 examples), and imidazoles (3 examples). Our study represents a unique gold-catalyzed reaction between alkynes and sulfur ylides, and also includes the first aza-heterocycle synthesis that proceeds by intermolecular nitrene transfer followed by cyclopropanation of the α-imino gold carbenes. Moreover, an unexpected synthesis of 4-acylquinolines (3 examples) from 2-acylphenyl sulfilimines and propargylic silyl ether derivatives by a 1,2-hydride shift onto the α-imino gold carbene and a subsequent Mukaiyama aldol cyclization was discovered.

We herein report the gold(iii)-catalyzed selective annulation of anthranils with N-allylynamides under mild conditions. By trapping the in situ-generated α-imino gold carbenes, 3-azabicyclo[3.1.0]hexan-2-imines were obtained in high synthetic efficiency. The reaction, which can be conducted in the gram scale, tolerates electron-rich and electron-deficient anthranils as well as a diverse set of functionalized ynamides (aryl- and alkyl-substituted terminal).

We report a novel example of electro-mediated photoredox catalysis (e-PRC) in the reductive cleavage of C(sp 3 )-O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E -selective and can be made Z -selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation and catalyst structural variations reveal that our new naphthalene monoimide-type catalyst allows for a more intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity-determining C(sp 3 )-O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions i) tolerate aryl chlorides/bromides and ii) do not give rise to Birch-type reductions., Accepted Article

We report a novel example of electro‐mediated photoredox catalysis (e‐PRC) in the reductive cleavage of C(sp3)−O bonds of phosphinated alcohols to alkyl carbanions. As well as deoxygenations, olefinations are reported which are E‐selective and can be made Z‐selective in a tandem reduction/photosensitization process where both steps are photoelectrochemically promoted. Spectroscopy, computation, and catalyst structural variations reveal that our new naphthalene monoimide‐type catalyst allows for an intimate dispersive precomplexation of its radical anion form with the phosphinate substrate, facilitating a reactivity‐determining C(sp3)−O cleavage. Surprisingly and in contrast to previously reported photoexcited radical anion chemistries, our conditions tolerate aryl chlorides/bromides and do not give rise to Birch‐type reductions., Beyond C(sp2)–X cleavage: We report reductive cleavages of C(sp3)−O bonds of phosphinated alcohols to alkyl carbanions by electro‐mediated photoredox catalysis. Deoxygenations as well as E‐ or Z‐selective olefinations are reported. Surprisingly, reactions tolerate C(sp2)–X cleavages such as aryl halides. Radical ion catalyst‐substrate preassembly is key in enabling reactivity and overturning conventional redox chemoselectivity.

Synthetic photoelectrochemistry (PEC) offers new prospects for the generation and handling of reactive intermediates. PEC permits selective single-electron transfer (SET) reactions in a much greener way and broadens the redox window of possible transformations. This Review discusses the combination of PEC with other reactivity paradigms, scalability up to multigram scale, novel selectivities in SET super-oxidations/reductions and the importance of precomplexation. Synthetic photoelectrochemistry (PEC) is receiving increasing attention as a new frontier for the generation and handling of reactive intermediates. PEC permits selective single-electron transfer (SET) reactions in a much greener way and broadens the redox window of possible transformations. Herein, the most recent contributions are reviewed, demonstrating exciting new opportunities, namely, the combination of PEC with other reactivity paradigms (hydrogen-atom transfer, radical polar crossover, energy transfer sensitization), scalability up to multigram scale, novel selectivities in SET super-oxidations/reductions and the importance of precomplexation to temporally enable excited radical ion catalysis. Die synthetische Photoelektrochemie (PEC) bietet neue Möglichkeiten für die Erzeugung und Handhabung reaktiver Zwischenstufen. Selektive Einelektronentransferreaktionen (SET) auf wesentlich umweltfreundlichere Weise und die Erweiterung des Redoxfensters erwecken Aufmerksamkeit. Dieser Aufsatz befasst sich mit den diesbezüglich neusten Beiträgen. Besprochen werden die Kombination von PEC mit anderen Reaktivitäten (Wasserstoffatomtransfer, radical–polar crossover, Energietransfer-Sensibilisierung), die Skalierbarkeit bis zum Multigramm-Maßstab, neuartige Selektivitäten bei SET-Superoxidationen/Reduktionen und die Bedeutung der Vorkomplexierung, um die Katalyse angeregter Radikalionen zeitlich zu ermöglichen.

A gold-catalyzed synthesis of tetrasubstituted 1,3-enynes from hypervalent iodine(III) reagents and activated alkenes is reported. This reaction involves an in situ formed alkynyl Au(III) species and a subsequent direct C(sp

The chemoselective cyclization of isocyanates with 2H-azirine was achieved with AuBr3 as catalyst. This transfer sets the stage for the synthesis of aromatic oxazole-ureas in a tandem process. The addition of a catalytic amount of phosphite enhances the process enormously. The reaction can also be performed in a one-pot process using benzoyl azide instead of isocyanate under the same conditions. A detailed study on the role of the phosphite that was applied as an additive revealed that only non-coordinated phosphite can reduce gold(III) and that gold(I) coordinated phosphite is not oxidized. Accompanied by the reduction of gold, HBr is generated in situ, which turned out to be the actual promotor in combination with the remaining AuBr3 . The positive effect of acid can be explained by a strong N-Au coordination, which tends to break more easily in the presence of small amount of protic acid in the reaction solution.

A new gold-catalyzed C–H annulation of sulfilimines with N-phenylynamides is presented. As key intermediates of this operationally simple reaction, the in situ generated α-imino gold carbenes insert into the ortho C–H bonds of the phenyl groups to afford 2-aminoindoles bearing a variety of substitution patterns in high selectivities. This reaction offers a facile approach to biologically important 2-aminoindoles by using inexpensive and readily available starting materials.

Gold-catalyzed formal 1,3-dipolar annulation between readily accessible N-pyridinylsulfilimines and ynamides is reported. A diverse set of imidazole derivatives is prepared from the corresponding sulfilimines and ynamides. These functionalized cyclic products can undergo further transformations to afford diverse imidazole frameworks. Moreover, in situ synthesis is feasible and shows good potential in the synthesis of nucleoside analogues.

In this paper, The binding of twelve 1,3-diazaheterocyclic compounds (1a-1 l) to the fat mass and obesity-associated (FTO) protein was investigated by fluorescence, UV-vis absorption spectroscopy and molecular modeling. Results indicated that the intrinsic fluorescence of FTO is quenched by the nine compounds (1a-1i) with a static quenching procedure. No interaction was observed between FTO protein and compounds (1j-1 l). The thermodynamic parameters obtained from the fluorescence data showed that the hydrophobic force played a major role in stabilizing the complex. The results of synchronous and three-dimensional fluorescence spectra showed that the conformation of FTO was changed. In addition, the influence of molecular structure on the quenching effect has been investigated.

The chemoselective cyclization of isocyanates with 2H-azirine was achieved with AuBr

An I2/KI-mediated oxidative N-N bond formation reaction is described. This new and environmentally benign approach allows for the convenient synthesis of a variety of 1,2,4-triazolo[1,5-a]pyridines and other 1,5-fused 1,2,4-triazoles from readily available N-aryl amidines in an efficient and scalable fashion.

A one-pot I2-mediated annulation reaction of substrates containing diamino groups and aldehydes has been developed via oxidative C–N bond formation. This general and environmentally benign synthetic approach provides facile access to a variety of 1,3-diazaheterocyclic compounds, including quinazolinones, benzimidazoles, and cyclic amidines.

2-Amino-substituted 1,3,4-oxadiazoles and 1,3,4-thiadiazoles were synthesized via condensation of semicarbazide/thiosemicarbazide and the corresponding aldehydes followed by I2-mediated oxidative C–O/C–S bond formation. This transition-metal-free sequential synthesis process is compatible with aromatic, aliphatic, and cinnamic aldehydes, providing facile access to a variety of diazole derivatives bearing a 2-amino substituent in an efficient and scalable fashion.

The present work reports the first solid phase synthesis of biologically interesting d - threo -1-phenyl-2-decanoylamino-3-morpholino-1-propanol ( d - threo -PDMP) derivatives. This synthetic strategy includes facile preparation of versatile azido intermediate ( 5 ) in a relatively short sequence and the subsequent derivatization of 5 , which led to a series of sulfonamide, urea and heterocycle substituted PDMP analogs ( 10 and 10 ′). With this method, a 5280-member compound library has been successfully built by IRORI Nanokan © system.

A novel and practical strategy for the construction of imidazo[1,2-a]pyridin-2-amine frameworks has been developed. The present sequential approach involves addition of arylamines to nitriles and I2 /KI-mediated oxidative C-N bond formation without purification of the intermediate amidines. This operationally simple synthetic process provides a facile access to a variety of new 2-amino substituted imidazo[1,2-a]pyridines and related heterocyclic compounds in an efficient and scalable fashion.

A novel and practical strategy for the construction of imidazo[1,2-a]pyridin-2-amine frameworks has been developed. The present sequential approach involves addition of arylamines to nitriles and I2 /KI-mediated oxidative C-N bond formation without purification of the intermediate amidines. This operationally simple synthetic process provides a facile access to a variety of new 2-amino substituted imidazo[1,2-a]pyridines and related heterocyclic compounds in an efficient and scalable fashion.

An I2/KI-mediated oxidative N–N bond formation reaction is described. This new and environmentally benign approach allows for the convenient synthesis of a variety of 1,2,4-triazolo[1,5-a]pyridines and other 1,5-fused 1,2,4-triazoles from readily available N-aryl amidines in an efficient and scalable fashion.

A one-pot I2-mediated annulation reaction of substrates containing diamino groups and aldehydes has been developed via oxidative C–N bond formation. This general and environmentally benign synthetic approach provides facile access to a variety of 1,3-diazaheterocyclic compounds, including quinazolinones, benzimidazoles, and cyclic amidines.

The transition metal free sequence allows a facile and generally high-yielding approach to the title heterocycles with a use of aromatic, aliphatic, and cinnamic aldehyde reactants.

A series of new 2′-deoxy-2′-β-fluoro-4′-azido-β- d -arabinofuranosyl cytidine derivatives bearing heteroatom-containing N4-substituents were designed and synthesized. Antiviral screening in HepG2.2.15 cells identified three analogs (1a, 1d & 1g) with good anti-HBV activity and low cytotoxicty. Of them, compound 1g exhibited significant inhibitory activity on both HBV antigens secretion (EC50, HBsAg = 9 nM, EC50, HBeAg = 0.25 μM) and viral DNA replication (intracellular, EC50 = 0.099 μM; extracellular, EC50