Practical iridium-catalyzed direct α-arylation of N-heteroarenes with (hetero)arylboronic acids by H2O-mediated H2 evolution

5-Aminopyrazole Dimerization: Cu-Promoted Switchable Synthesis of Pyrazole-Fused Pyridazines and Pyrazines via Direct Coupling of C-H/N-H, C-H/C-H, and N-H/N-H Bonds

A Cu-promoted highly chemoselective dimerization of 5-aminopyrazoles to produce pyrazole-fused pyridazines and pyrazines is reported. The protocol generates switchable products via the direct coupling of C-H/N-H, C-H/C-H and N-H/N-H bonds, with the merits of broad substrate scope and high functional group compatibility. Gram-scale experiments demonstrated the potential applications of this reaction. Moreover, the preliminary fluorescence results uncovered that dipyrazole-fused pyridazines and pyrazines may have some potential applications in materials chemistry.

Iron-Catalyzed C-H Arylphosphorylation of Quinoxalines

A one-pot strategy for iron-catalyzed C2,3-H arylphosphorylation of electron-deficient quinoxalines with phosphines and aryl compounds is reported. The proposed method features the use of non-noble metal catalysts, the capacity of utilizing multiple aryl compounds as substrates, the simultaneous formation of C-P and C-C bonds in one pot, the simplicity of its operation, the mildness of the reaction conditions, and its compatibility with a wide range of substrates. Moreover, it offers a practical route for direct access to 2-aryl-3-phosphino N-heteroarenes, a class of potential cyclometalated C^N and N^P bidentate ligands that are difficult to prepare with existing C(sp2)-H functionalization methods.

Large Language Model-Based Natural Language Encoding Could Be All You Need for Drug Biomedical Association Prediction

Analyzing drug-related interactions in the field of biomedicine has been a critical aspect of drug discovery and development. While various artificial intelligence (AI)-based tools have been proposed to analyze drug biomedical associations (DBAs), their feature encoding did not adequately account for crucial biomedical functions and semantic concepts, thereby still hindering their progress. Since the advent of ChatGPT by OpenAI in 2022, large language models (LLMs) have demonstrated rapid growth and significant success across various applications. Herein, LEDAP was introduced, which uniquely leveraged LLM-based biotext feature encoding for predicting drug-disease associations, drug-drug interactions, and drug-side effect associations. Benefiting from the large-scale knowledgebase pre-training, LLMs had great potential in drug development analysis owing to their holistic understanding of natural language and human topics. LEDAP illustrated its notable competitiveness in comparison with other popular DBA analysis tools. Specifically, even in simple conjunction with classical machine learning methods, LLM-based feature representations consistently enabled satisfactory performance across diverse DBA tasks like binary classification, multiclass classification, and regression. Our findings underpinned the considerable potential of LLMs in drug development research, indicating a catalyst for further progress in related fields.

Divergent Synthesis of Cyclopropanated Tetrahydroquinolines by Tandem Functionalization of Quinoline Derivatives

Here, reported is a new method for divergent synthesis of functionalized tetrahydroquinolines (THQs), featuring a biomedically interesting azabicyclo[4.1.0]heptane core, proceeding with mild conditions, good substrate and functionality tolerance, and operational simplicity. Mechanistic studies suggest that the products are formed via carbonucleophilic 1,4-addition-induced dearomatization of quinolinium salts and intramolecular cyclopropanation with α-halo ketones followed by α-nucleophilic addition with different nucleophiles. The present work lays a foundation to access new N-heterocycles via the dearomative tandem functionalization of azaarenes.

In Situ Activation of Azaarenes and Terminal Alkynes to Construct Bridged Polycyclic Compounds Containing Isoquinolinones

A copper-catalyzed [4+2] cyclization reaction of isoquinolines and alkynes is developed for the one-step construction of isoquinolinone derivatives with multisubstituted bridging rings. The unique feature of this three-component tandem cyclization reaction is the functionalization of the C1, N2, C3, and C4 positions of 3-haloisoquinolines via the construction of new C-N, C═O, and C-C bonds. This dearomatization strategy for the synthesis of structurally complex isoquinolinone-bridged cyclic compounds offers good chemoselectivity, broad functional group compatibility, greenness, and high step economy.

Nickel-catalyzed mild synthesis of functional γ-amino butyric acid esters via direct α-C(sp3)-H allylation of N-alkyl anilines with allyl sulfones

Herein, by employing a readily available Ni(OAc)2·4H2O/TBHP catalyst system, we present a new method for mild synthesis of α-methylene-γ-amino butyric acid esters via direct α-C(sp3)-H allylation of N-alkyl anilines with allyl sulfones under oxidative nickel catalysis. The synthetic protocol proceeds with good substrate and functional group compatibility, operational simplicity, the use of base metal catalysts and easily accessible feedstocks, and no need for pre-functionalization of the α-site of N-alkyl anilines. In addition, the obtained products are applicable for further elaboration of functional molecules.

Dearomative bis-functionalization of quinoxalines and bis-N-arylation of (benz)imidazoles via Cu(II)-mediated addition of boronic acids

A Cu(OTf)₂-mediated regioselective dearomative aryl-hydroxylation across the C(sp²)N bond of 2-aryl quinoxalines and bis-N-arylation of (benz)imidazoles were developed using aryl boronic acids. For the dearomative aryl-hydroxylation, the C-center should be electrophilic (ca. 0.08), the N-center nucleophilic (ca. -0.50), and the C(sp²)N bond polarized (Δe = 0.609).

Water-mediated radical C-H tosylation of alkenes with tosyl cyanide

The water-mediated tosylation of alkenes with tosyl cyanide was discovered. Experimental investigations revealed that the reaction was initiated by the in situ formation of sulfinyl sulfone in the presence of water. The sulfinyl sulfone species decomposed to a sulfonyl radical and a sulfinyl radical through homolytic fission. The vinyl sulfone was afforded via sequential addition of the alkene to the sulfonyl radical and the sulfinyl radical, followed by β-elimination of a sulfinyl moiety.

Selective access to fused tetrahydroquinolines via a copper-catalysed oxidative three-component annulation reaction

Via a copper-catalyzed three-component annulation reaction, we herein report a new method for the direct and syn-selective construction of cyclic ether-fused tetrahydroquinolines from readily available secondary anilines, saturated five or six-membered cyclic ethers, and paraformaldehyde. The synthesis features operational simplicity, excellent step and atom efficiency, good functionality and substrate compatibility. In comparison with the reported synthetic protocols capable of synthesizing N-alkyl fused tetrahydroquinolines, this newly developed chemistry allows access to both N-alkyl and N-aryl products. The current work complements the preparation of fused tetrahydroquinolines.

Copper-catalyzed [3+3] annulation of ketones with oxime acetates for the synthesis of pyridines

A novel and efficient copper-catalyzed strategy for the synthesis of diverse pyridines through the [3+3] annulation of ketones with oxime acetates has been reported. It is very convenient to obtain various unsymmetrical 2,6-diarylpyridines by changing different substrates. The rare copper-catalyzed direct difunctionalization of saturated ketones for the synthesis of nitrogen heterocycles is developed. This protocol has excellent functional group tolerance, readily available raw materials, high chemoselectivity and broad substrate scope.

Silver Ions Promoted Palladium-Catalyzed Inactive β-C(sp3)-H Bond Arylation in Batch and Continuous-Flow Conditions

A palladium(II)-catalyzed protocol for inactive β-C(sp³)-H bond functionalization has been first accomplished. The reaction proceeds through five-membered carbocycles for the formation of C-C bonds via the Pd(II)/Pd(IV) cycle. This reaction was carried out with various aryl iodides and benzothiazoles/benzoxazoles/benzimidazoles, which were well-tolerated in this reaction and successfully generated β-C(sp³)-H arylated products. Further implementation of this batch protocol to continuous flow by utilizing a PTFE (polytetrafluoroethylene) capillary reactor enhanced the reaction efficiency and decreased the reaction time (18.4 min) as compared to batch conditions (8 h). Even on the gram scale, the process produced excellent yield with negligible diarylations. Functional group tolerance, a continuous-flow approach, and easy-to-handle reaction conditions make this inactive β-C(sp³)-H bond functionalization protocol very attractive.

Water-Mediated ortho-Carboxymethylation of Aryl Ketones under Ir(III)-Catalytic Conditions: Step Economy Total Synthesis of Cytosporones A-C

An expeditious Ir(III)-catalyzed carboxymethylation of aryl ketone with diazotized Meldrum's acid has been developed in aqueous medium. Flavanone and chromanone were also found to be facile substrates with the developed catalytic system. Mechanistic studies revealed the active catalytic species and the role of water in the reaction process as hydroxy and proton sources. Employing the developed method, total synthesis of cytosporone A was achieved in two steps and that of cytosporones B-C was achieved in three steps starting from resorcinol.

Construction of Fluorinated Amino Acid Derivatives via Cobalt-Catalyzed Oxidative Difunctionalization of Cyclic Ethers

Via difunctionalization of the α- and β-sites of cyclic ethers, we herein demonstrate a new synthetic method for the efficient construction of novel fluorinated γ-amino acid esters by employing a CoBr₂/m-CPBA catalyst system. Several cyclic ethers were transformed in combination with a vast range of amines and ethyl trifluoropyruvate into the desired products under mild conditions, making this method a practical platform to enrich the library of fluorinated amino acid derivatives from cost-effective and readily available feedstocks.

A cooperative Pd/Co catalysis system for the asymmetric (4+2) cycloaddition of vinyl benzoxazinones with N-acylpyrazoles

Transition metal-catalyzed cycloaddition has been established as a powerful tool for heterocycle synthesis. Despite impressive advances, the exploitation of new catalysis strategies and systems is still highly significant to enrich the heterocycle family. Herein, we disclosed a cooperative catalysis system merging an achiral Pd catalyst and a chiral Co catalyst for the asymmetric [4+2] cycloaddition between vinyl benzoxazinones and N-acylpyrazoles. Chiral tetrahydroquinolines bearing two contiguous, unusual cis-configured stereocenters were produced in high yields and enantio- and diastereoselectivities. The pyrazole directing group can be easily converted into many other functional groups, thus demonstrating the flexibility of the present methodology.

Synthesis of functionalized benzimidazoles via oxidative tandem quartic C-H aminations and cleavage of C-N and C-C bonds

Via aerobic copper-catalyzed tandem quartic C-H aminations, we herein present an unprecedented approach for the synthesis of functionalized benzimidazoles from aniline derivatives and 2-substituted cyclic amines. The cyclic amines act as the CN building blocks and are involved in the annulation reaction by cleavage of inert α-C-N and β-C-C bonds. The synthetic protocol features high selectivity, no need for specific aminating agents, mild conditions, and the use of a naturally abundant [Cu]/O₂ catalyst system.