A General Copper-Box System for the Asymmetric Arylative Functionalization of Benzylic, Propargylic or Allenylic Radicals

Radical-involved arylative cross-coupling reactions have recently emerged as an attractive strategy to access valuable aryl-substituted motifs. However, there still exist several challenges such as limited scope of radical precursors/acceptors, and lack of general asymmetric catalytic systems, especially regarding the multicomponent variants. Herein, we reported a general copper-Box system for asymmetric three-component arylative radical cross-coupling of vinylarenes and 1,3-enynes, with oxime carbonates and aryl boronic acids. The reactions proceed under practical conditions in the absence or presence of visible-light irradiation, affording chiral 1,1-diarylalkanes, benzylic alkynes and allenes with good enantioselectivities. Mechanistic studies imply that the copper/Box complexes play a dual role in both radical generation and ensuing asymmetric cross-coupling. In the cases of 1,3-enynes, visible-light irradiation could improve the activity of copper/Box complex toward the initial radical generation, enabling better efficiency match between radical formation and cross-coupling.

Fe-Catalyzed Fluoroalkyl(hetero)arylation of Vinyl Azaarenes: Rapid and Modular Synthesis of Unsymmetrical 1,1-Bis(hetero)arylalkanes

In contrast to transition-metal-catalyzed difunctionalization of activated alkenes, selective alkylarylation of vinyl azaarenes is underdeveloped. Consequently, the lack of modular and rapid syntheses of 1,1-bis(hetero)arylalkanes limits their exploration in medicinal chemistry. Herein we report a protocol using commercially available iron salts, bisphosphine ligands, fluoroalkyl halides, and Grignard reagents that enables the selective 1,2-fluoroalkyl(hetero)arylation of vinyl azaarenes. We demonstrate the versatility and robustness of the method through the selective synthesis of a range of unsymmetrical 1,1-bis(hetero)arylalkenes, including pyridine N-oxides, triazoles, pyrazines, carbazoles, indazoles, and 1,2-azaborines. Mechanistic insights from experimental and computational investigations support a radical pathway and provide insights into the role of non-covalent interactions in iron catalysis.

Access to Substituted 1,1-Diarylalkanes by Friedel-Crafts Benzylations Mediated by FeCl3-based Deep Eutectic Solvents

The development of new, more efficient Friedel-Crafts benzylation methodologies that provide access to 1,1-diarylalkanes is an important objective of interest for the production of pharmaceuticals and fine chemical products. In this regard, this study introduces a novel synthetic route to 1,1-diarylalkanes conducted in the Deep Eutectic Solvent (DES) 3 FeCl3 ⋅ 6 H2O/Gly, which serves as both a reaction medium and promoter. Under these conditions, Friedel-Crafts benzylations of various arenes bearing activating and deactivating ortho-/para-directing groups, can be performed using diverse benzylating reagents such as styrenes, alcohols, acetates, ethers, and chlorides. Importantly, highly electronically deactivated electrophiles, including those with CF3 and NO2 groups, are suitable substrates. This methodology provides a wide range of asymmetric 1,1-diarylalkanes (up to 132 examples) with generally good yields and high regioselectivities. The efficiency of this approach was demonstrated with the multigram-scale synthesis (10 mmol) of 1-phenyl-1-xylyl ethane (PXE), a liquid with great industrial applicability. Moreover, the Fe(III)-based DES could be reused for 20 consecutive cycles with no appreciable erosion of the yields.

Hydrogen Source Tuned Regiodivergent Asymmetric Hydroalkylations of 2-Substituted 1,3-Dienes with Aldehydes by Cobalt-Catalysis

Catalytic methods allowing for the reliable prediction and control of diverse regioselectivity along with the control of enantioselectivity to access different regio- and enantiomers by switching the least reaction parameters are one of the most attractive ways in organic synthesis, which provide access to diverse enantioenriched architectures from identical starting materials. Herein, a Co-catalyzed regiodivergent and enantioselective reductive hydroalkylation of 1,3-dienes with aldehydes has been achieved, furnishing different enantioenriched homoallylic alcohol architectures in good levels of enantioselectivity. The reaction features the switch of regioselectivity tuned by the selection of proton source. The use of an acid as proton source provided asymmetric 1,2-hydroalkylation products under reductive conditions, yet asymmetric 4,3-hydroalkylation products were obtained with silane as hydride source. This catalytic protocol allows for the access of homoallylic alcohols with two continuous saturated carbon centers in good levels of regio-, diastereo-, and enantioselectivity.

Nickel-catalysed enantioselective alkene dicarbofunctionalization enabled by photochemical aliphatic C-H bond activation

The development of novel strategies to rapidly construct complex chiral molecules from readily available feedstocks is a long-term pursuit in the chemistry community. Radical-mediated alkene difunctionalizations represent an excellent platform towards this goal. However, asymmetric versions remain highly challenging, and more importantly, examples featuring simple hydrocarbons as reaction partners are elusive. Here we report an asymmetric three-component alkene dicarbofunctionalization capitalizing on the direct activation of C(sp 3)-H bonds through the combination of photocatalysed hydrogen atom transfer and nickel catalysis. This protocol provides an efficient platform for installing two vicinal carbon-carbon bonds across alkenes in an atom-economic fashion, providing a wide array of high-value chiral α-aryl/alkenyl carbonyls and phosphonates, as well as 1,1-diarylalkanes from ubiquitous alkane, ether and alcohol feedstocks. This method exhibits operational simplicity, broad substrate scope and excellent regioselectivity, chemoselectivity and enantioselectivity. The compatibility with bioactive motifs and expedient synthesis of pharmaceutically relevant molecules highlight the synthetic potential of this protocol.

Orthogonal sp3-Ge/B Bimetallic Modules: Enantioselective Construction and Enantiospecific Cross-Coupling

In this study, a series of enantioenriched sp3-Ge/B bimetallic modules were successfully synthesized via an enantioselective copper-catalyzed hydroboration of carbagermatrane (Ge)-containing alkenes. Orthogonal cross-coupling selectivity under different Pd-catalyzed conditions was achieved in an enantiospecific manner. Notably, the chiral secondary Ge exhibited a remarkable transmetallation ability prior to primary or secondary Bpin. The effectiveness of this Ge/B bimetallic strategy was further demonstrated through the development of new functional small molecules with Aggregation-Induced Emission (AIE) and Circularly Polarized Luminescence (CPL) performance. This represents the first successful example of synthesis of enantioenriched alkylgermanium reagents that permit enantiospecific cross-coupling reactions.

Photoactivation of Hydrazones for the Synthesis of Diarylalkanes and Trialkylmethylboronates: The Key Role Played by Soluble Base

The synthesis of diaryl alkanes and tertiary organoboronates via Barluenga coupling at room temperature occurred via photoactivated conversion of aryl sulfonyl hydrazones to diazo compounds in the presence of soluble bases. The combination of arylsulfonyl hydrazone and a soluble base is necessary to provide a near-UV chromophore. Using aromatic hydrazones and aromatic boronic acids resulted in rapid deboronation because of the instability of dibenzylic boron intermediates. Alkyl hydrazones allowed the isolation of derivatives of the tertiary boronate.

Facile Friedel-Crafts alkylation of arenes under solvent-free conditions

The Friedel-Crafts alkylation of arenes is an important part of electrophilic aromatic substitution reactions. However, the reactivity of arenes is weakened by electron-withdrawing substituents, leading to limited substrate scopes and applications. Herein, we developed an efficient HOTf-promoted Friedel-Crafts alkylation reaction of broad arenes with α-aryl-α-diazoesters under metal-free and solvent-free conditions.

Tunable C-H functionalization and dearomatization enabled by an organic photocatalyst

C-H functionalization and dearomatization constitute fundamental transformations of aromatic compounds, which find wide applications in various research areas. However, achieving both transformations from the same substrates with a single catalyst by operating a distinct mechanism remains challenging. Here, we report a photocatalytic strategy to modulate the reaction pathways that can be directed toward either C-H functionalization or dearomatization under redox-neutral or net-reductive conditions, respectively. Two sets of indoles and indolines bearing tertiary alcohols are divergently furnished with good yields and high selectivity. The key to success is the introduction of isoazatruxene ITN-2 as a novel photocatalyst (PC), which outperforms the commonly used PCs. The ready synthesis and high modulability of isoazatruxene type PCs indicate their great application potential.

Light-induced arylation (alkylation) of N-sulfonylhydrazones with boronic acids

Di- and triarylmethanes are an important class of compounds in many fields. Here, we report an efficient light-induced arylation (alkylation) for the synthesis of diarylmethanes, bis(diarylmethyl)benzenes, arylalkylmethanes, and triarylmethanes from readily accessible N-sulfonylhydrazones and aryl/alkylboronic acids with the aid of Cs2CO3. In the presence of light, the synthesis of diarylmethanes was also achieved from aldehydes in a one-pot manner via a three-component approach in good yields. Furthermore, we have demonstrated the synthetic utility by synthesizing organoboron compounds and 2°-alcohol.

Enantioselective Desymmetrization of Trifluoromethylated Tertiary Benzhydrols via Hydrogen-Acceptor-Free Ir-Catalyzed Dehydrogenative C-H Silylation: Decisive Role of the Trifluoromethyl Group

Although the trifluoromethyl (CF3) group is one of the most important fluorinated groups owing to its significant ability to modulate pharmacological properties, constructing trifluoromethylated stereogenic centers in an enantioselective manner has been a formidable challenge. Herein, we report the development of the enantioselective desymmetrization of trifluoromethylated benzhydrols via intramolecular dehydrogenative silylation using Ir catalysts with chiral pyridine-oxazoline (PyOX) ligands. The produced benzoxasilol was transformed into several unsymmetrical benzhydrols via iododesilylation and subsequent transition-metal-catalyzed cross-coupling reactions. Moreover, the same Ir catalyst system was used for the kinetic resolution of unsymmetrical trifluoromethylated benzhydrols.

Synthesis of anti-depressant molecules via metal-catalyzed reactions: a review

Depression is one of the most mutilating conditions in the world today. It has been difficult to make advancements toward better, more effective therapies since the introduction of antidepressant medicines in the late 1950s. One important field of medicinal chemistry is the synthesis of antidepressant molecules through metal-catalyzed procedures. The important role that different transition metals, including iron, nickel, ruthenium, and others, serve as catalysts in the synthesis of antidepressants is examined in this review. Key structural motifs included in antidepressant drugs such as tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and others can be synthesized in a variety of effective ways using metal-catalyzed steps. This review examines current developments in the catalytic synthesis of antidepressants and their potential application over the previous thirteen years.

An Open-Air Palladium-Catalyzed Stereoselective O-Glycosylation of Glycals via in-situ Generation of gem-Disubstituted Methanols from p-Quinone Methides

We devised a palladium-catalyzed α-stereoselective glycosylation that incorporates oxygen via in-situ generation of gem-disubstituted methanols from p-quinone methides to access 2,3-unsaturated gem-diarylmethyl O-glycosides under open-air atmosphere at room temperature. Advantages of this environmentally friendly strategy include the absence of additives and ligands, using water as the green source of oxygen, mildest, operationally simple, exhibiting a wide functional group tolerance, and compatibility with a variety of glycal progenitors in appreciable yields. A mechanistic study has been verified via H2 18 O labeling, which validates that water (moisture) is a sole source of oxygen.

Direct C(sp3)-H Arylation of Unprotected Benzyl Anilines and Alkylarenes by Organocatalysis under Visible Light

Reported herein is direct C(sp3)-H arylation of unprotected benzyl anilines and alkylarenes via consecutive photoinduced electron transfer by visible light irradiation. Reductive quenching cycles and radical-radical cross-coupling were involved, and electron paramagnetic resonance experiments provide evidence for the formation of radical intermediates formed in situ. The protocol highlights transition metal free, external oxidant free, broad substrate scope, and high efficiency (>60 examples, up to 96%).

Dual-Catalysed Intermolecular Reductive Coupling of Dienes and Ketones

We report a mild, catalytic method for the intermolecular reductive coupling of feedstock dienes and styrenes with ketones. Our conditions allow concomitant formation of a cobalt hydride species and single-electron reduction of ketones. Subsequent selective hydrogen-atom transfer from the cobalt hydride generates an allylic radical which can selectively couple with the persistent radical-anion of the ketone. This radical-radical coupling negates unfavourable steric interactions of ionic pathways and avoids the unstable alkoxy radical of previous radical olefin-carbonyl couplings, which were limited, as a result, to aldehydes. Applications of this novel and straightforward approach include the efficient synthesis of drug molecules, key intermediates in drug synthesis and site-selective late-stage functionalisation.

Synthesis of Chiral Diarylmethylamides via Catalytic Asymmetric Aza-Michael Addition of Amides to ortho-Quinomethanes

Chiral diarylmethylamides are a privileged skeleton in many bioactive molecules. However, the enantioselective synthesis of such molecules remains a long-standing challenge in organic synthesis. Herein, we report a chiral bifunctional squaramide catalyzed asymmetric aza-Michael addition of amides to in situ generated ortho-quinomethanes, affording enantioenriched diarylmethylamides in good yields with excellent enantioselectivities. This work not only provides a new strategy for the construction of the diarylmethylamides but also represents the practicability of amides as nitrogen-nucleophiles in asymmetric organocatalysis.

Unlocking regioselective meta-alkylation with epoxides and oxetanes via dynamic kinetic catalyst control

Regioselective arene C-H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Herein, we report the meta-C-H bond alkylation of aromatics bearing N-directing groups using (hetero)aromatic epoxides as alkylating agents. This method results in complete regioselectivity on both the arene as well as the epoxide coupling partners, cleaving exclusively the benzylic C-O bond. Oxetanes, which are normally unreactive, also participate as alkylating reagents under the reaction conditions. Our mechanistic studies reveal an unexpected reversible epoxide ring opening process undergoing catalyst-controlled regioselection, as key for the observed high regioselectivities.

A general approach to stereospecific Pd-catalyzed cross-coupling reactions of benzylic stereocenters

We have developed a general process for the formation of enantioenriched benzylic stereocenters via stereospecific Pd-catalyzed cross-coupling reactions of enantioenriched benzylic tricyclohexyltin nucleophiles. This process proceeds with excellent stereospecificity for a remarkably broad scope of electrophilic coupling partners including aryl and heteroaryl halides and triflates, acid chlorides, thioesters, chloroformates, and carbamoyl chlorides. Thus, enantioenriched 1,1-diarylalkanes as well as formal products of asymmetric enolate arylation are readily accessed using this approach. We additionally provide the first demonstration of a Sn-selective cross-coupling reaction using a vicinal alkylborylstannane nucleophile. In these reactions, the presence of cyclohexyl spectator ligands on tin is essential to ensure selective transfer of the secondary benzylic unit from tin to palladium.

Nickel-Catalyzed Regioselectivity-Switchable Hydroheteroarylation of Vinylarenes with Electron-Rich Heteroarenes

We report the first example of a regioselectivity switch in the hydroheteroarylation of vinylarenes with electron-rich heteroarenes, including benzofurans, benzothiophenes, and indoles, using an expedient ligand-controlled strategy. In the presence of NaOtBu, Ni(IMesMe)[P(OEt)3]Br2 yields C2-alkylated heteroarenes with high branched selectivity, whereas the use of Ni(IPr*OMe)[P(OEt)3]Br2 favors the formation of the corresponding linear products. This robust method also provides easy access to a range of C2-alkylated electron-rich heteroarenes without employing directing groups.

Transition-metal-free and additive-free intermolecular hydroarylation of alkenes with indoles in hexafluoroisopropanol

Hydroarylation of alkenes is one of the most straightforward and atom-economical strategy for the construction of multi-aryl-substituted alkanes, but systematic studies have been limited to transition metal catalysis. Here we report a hexafluoroisopropanol (HFIP)-promoted hydroarylation of alkenes with indoles without the presence of transition metal catalysts or any additive. HFIP was the only reagent used in this work, and could be easily removed via evaporation, and recovered via distillation in industry settings. This reaction was shown to provide an efficient, clean and operationally simple procedure with a remarkable substrate scope and versatile transformations, delivering a variety of multi-aryl alkanes incorporating the indole motif. In preliminary studies, several of these products showed biologically activity against cells from an array of human cancer cell lines. A mechanistic study was also carried out and suggested that the quinone methide might be the key intermediate. And in contrast to the conclusions of a previous report, the current work suggested that protonation by HFIP might not be the rate-determining step.

Asymmetric total synthesis of diosniponols A and B

A concise asymmetric total synthesis of diosniponols A and B has been achieved based on an enantioselective Jacobsen kinetic resolution of racemic epoxide and the important 2,3-dihydro-4H-pyran-4-one moiety being installed by the metal-free δ-hydroxyalkynone rearrangement catalyzed by p-TsOH. A diastereoselective catalytic hydrogenation set the required all-syn stereochemistry leading to diosniponol A, which then, under the Mitsunobu inversion conditions, provided diosniponol B. The structure and absolute stereochemistry of the natural products were further confirmed.

Amino Acid-Derived Ionic Chiral Catalysts Enable Desymmetrizing Cross-Coupling to Remote Acyclic Quaternary Stereocenters

Synthetic application of asymmetric catalysis relies on strategic alignment of bond construction to creation of chirality of a target molecule. Remote desymmetrization offers distinctive advantages of spatial decoupling of catalytic transformation and generation of a stereogenic element. However, such spatial separation presents substantial difficulties for the chiral catalyst to discriminate distant enantiotopic sites through a reaction three or more bonds away from a prochirality center. Here, we report a strategy that establishes acyclic quaternary carbon stereocenters through cross-coupling reactions at distal positions of aryl substituents. The new class of amino acid-derived ionic chiral catalysts enables desymmetrizing (enantiotopic-group-selective) Suzuki-Miyaura reaction, Sonogashira reaction, and Buchwald-Hartwig amination between diverse diarylmethane scaffolds and aryl, alkynyl, and amino coupling partners, providing rapid access to enantioenriched molecules that project substituents to widely spaced positions in the three-dimensional space. Experimental and computational investigations reveal electrostatic steering of substrates by the C-terminus of chiral ligands through ionic interactions. Cooperative ion-dipole interactions between the catalyst's amide group and potassium cation aid in the preorganization that transmits asymmetry to the product. This study demonstrates that it is practical to achieve precise long-range stereocontrol through engineering the spatial arrangements of the ionic catalysts' substrate-recognizing groups and metal centers.

Switchable Direct Oxygenative Arylation of C(sp3)-H Bonds via Electrophotocatalysis

A metal-free electrophotochemical C(sp3)-H arylation was developed under mild conditions. This method enables a switchable synthesis of diaryl alcohols and diaryl alkanes from inactive benzylic carbons. More importantly, a cheap and safe mediator N-chlorosuccinimide (NCS) was developed, which was employed for the hydrogen atom transfer (HAT) process of the benzylic C-H bond. In addition, this active radical was captured and identified by electron paramagnetic resonance (EPR).

Iron-mediated modular decarboxylative cross-nucleophile coupling

Carboxylic acids are valuable building blocks for pharmaceutical discovery because of their chemical stability, commercial availability, and structural diversity. Decarboxylative coupling reactions enable versatile functionalization of these feedstock chemicals, but many of the most general methods require prefunctionalization of carboxylic acids with redox-active moieties. These internal oxidants can be costly, their installation impedes rapid library synthesis, and their use results in environmentally problematic organic byproducts. We report herein a method for the direct decarboxylative cross-coupling of native carboxylic acids with nucleophilic coupling partners mediated by inexpensive, terrestrially abundant, and nontoxic Fe(III) salts. This method involves an initial photochemical decarboxylation followed by radical-polar crossover, which enables the construction of diverse carbon-carbon, carbon-oxygen, and carbon-nitrogen bonds with remarkable generality.

Enantioselective Intramolecular α-Arylation of Benzylamine Derivatives: Synthesis of a Precursor to Levocetirizine

A practical, transition metal-free method allows the enantioselective synthesis of α,α-diarylmethylamines by asymmetric α-arylation of benzylamines. Enantioselective lithiation of N'-aryl-N-benzyl-N-isopropyl ureas using a chiral lithium amide base generates a benzyllithium that undergoes an unactivated stereospecific intramolecular nucleophilic aromatic substitution to generate an α,α-diarylmethylamine in the form of its urea derivative, in up to >99 % ee. Treatment with acid induces an "azatropic shift" with retention of configuration, the product of which may be hydrolysed to the target amine.

Substitution controlled aryne insertion: synthesis of diarylmethane/chromones

Aryne insertion reaction with 2-aroyl malonates/cyanoesters lead to the formation of diarylmethane or chromones depending on the substitution on the aryne ring. The presence of an electronegative atom at the ortho position of arynes generates chromones, whereas other arynes lead to the formation of diarylmethanes, via a cascade double aryne insertion.

Photoinduced Vicinal 1,2-Difunctionalization of Olefins for the Synthesis of Alkyl Sulfonamides

Alkyl sulfonamides are an important class of bioactive molecules. Historical syntheses have relied on multistep sequences incorporating harsh reaction conditions. Photochemical methods have been limited to hydrosulfamoylation, installing only one substituent across an olefin. Herein, radical/polar crossover (RPC) is used to establish the first multicomponent 1,2-difunctionalization reaction incorporating a sulfonamide moiety and a second reaction partner. This protocol, exemplified on a range of olefins, utilizes various commercial sulfamoyl chlorides and organotrifluoroborates as coupling partners.

Atom-Economic Synthesis of Unsymmetrical gem-Diarylmethylthio/Seleno Glycosides via Base Mediated C(O)-S/Se Bond Cleavage and Acyl Transfer Approach of Glycosylthio/Selenoacetates

Herein, we invented the Cs₂CO₃-mediated atom economic method that streamlines the scission of the C(O)-S/Se bond involving the in situ generation of an anomeric thiolate/selenolate anion, which reacted with p-QMs to yield novel unsymmetrical gem-diarylmethylthio/seleno glycosides while retaining the anomeric stereochemistry. Notably, the key features of this protocol involve unprecedented long-range acyl transfer (from S/Se to O), thus affording acylation of the final product which is not yet reported by classical methods. This straightforward protocol offers a mild, short reaction time, synthetically simple approach, and compatibility with 8 types of sugar along with phenylthio/benzylseleno esters.

Efficient Synthesis of Diaryl Quaternary Centers by Rh(II)/Xantphos Catalyzed Relay C-H Functionalization and Allylic Alkylation

A three-component reaction of N, N-disubstituted aniline, α-diazo ester, and an allylic electrophile has been realized by [Rh(II)]₂ /Xantphos catalysis, providing a direct access to various aniline derivatives bearing diaryl allylic quaternary centers in good yields. The synthetic utility of this protocol was demonstrated by facile derivatization of the products for preparation of biologically relevant molecules and structural scaffolds, which offers a high potential for increasing the molecular diversity. Mechanistic studies identified α, α-diarylacetate species as an active intermediate, thereby revealing the presence of a C(sp² )-H functionalization of aniline derivatives/allylic alkylation cascade in this attractive catalytic transformation.

New imino-methoxy derivatives: design, synthesis, characterization, antimicrobial activity, DNA interaction and molecular docking studies

Four new diarylmethylamine imine compounds (5a-5d) were prepared in order to examine their DNA binding properties, antimicrobial activity and molecular docking. The compounds were characterized by the common spectroscopic and analytic methods. Furthermore, solid-state structure of compounds 5a and 5c were determined by single-crystal X-ray diffraction studies. The compounds were then investigated for their DNA binding properties employing UV absorption, fluorescence spectroscopy under the physiological pH condition Tris-HCl buffer at pH 7.4. The compounds 5a-5d showed moderate binding constants with Kb values of 3.56 ± 0.3 × 10⁴, 2.18 ± 0.2 × 10⁵, 1.44 ± 0.3 × 10⁵ and 2.56 ± 0.3 × 10⁴ M^-1, respectively. The molecular dockings were performed to investigate the ligand-DNA interactions. The in-silico DNA-compound interaction studies showed that the compounds interact with DNA in groove binding mode. Antimicrobial activity studies of imine compounds were tested against E. coli as bacteria, S. typhimurium, S. aureus, B. cereus, B. subtilis, and C. albicans as fungi. While all compounds show moderate activity against bacteria, no activity against fungi has been investigated.Communicated by Ramaswamy H. Sarma.

Ligand-enabled Ni-catalyzed hydroarylation and hydroalkenylation of internal alkenes with organoborons

The transition metal-catalyzed hydrofunctionalization of alkenes offers an efficient solution for the rapid construction of complex functional molecules, and significant progress has been made during last decades. However, the hydrofunctionalization of internal alkenes remains a significant challenge due to low reactivity and the difficulties of controlling the regioselectivity. Here, we report the hydroarylation and hydroalkenylation of internal alkenes lacking a directing group with aryl and alkenyl boronic acids in the presence of a nickel catalyst, featuring a broad substrate scope and wide functional group tolerance under redox-neutral conditions. The key to achieving this reaction is the identification of a bulky 1-adamantyl β-diketone ligand, which is capable of overcoming the low reactivity of internal 1,2-disubstituted alkenes. Preliminary mechanistic studies unveiled that this reaction undergoes an Ar-Ni(II)-H initiated hydroarylation process, which is generated by the oxidative addition of alcoholic solvent with Ni(0) species and sequential transmetalation. In addition, the oxidative addition of the alcoholic solvent proves to be the turnover-limiting step.

A Multi-Objective Active Learning Platform and Web App for Reaction Optimization

We report the development of an open-source experimental design via Bayesian optimization platform for multi-objective reaction optimization. Using high-throughput experimentation (HTE) and virtual screening data sets containing high-dimensional continuous and discrete variables, we optimized the performance of the platform by fine-tuning the algorithm components such as reaction encodings, surrogate model parameters, and initialization techniques. Having established the framework, we applied the optimizer to real-world test scenarios for the simultaneous optimization of the reaction yield and enantioselectivity in a Ni/photoredox-catalyzed enantioselective cross-electrophile coupling of styrene oxide with two different aryl iodide substrates. Starting with no previous experimental data, the Bayesian optimizer identified reaction conditions that surpassed the previously human-driven optimization campaigns within 15 and 24 experiments, for each substrate, among 1728 possible configurations available in each optimization. To make the platform more accessible to nonexperts, we developed a graphical user interface (GUI) that can be accessed online through a web-based application and incorporated features such as condition modification on the fly and data visualization. This web application does not require software installation, removing any programming barrier to use the platform, which enables chemists to integrate Bayesian optimization routines into their everyday laboratory practices.

Reductive-Delay Heck 1,1-Diarylation of Terminal Alkenes

Pd-catalyzed chemo- and regiocontrollable 1,1-diarylation of unactivated aliphatic alkenes with two aryl halides was developed. Under the cationic reductive-delay Heck pathway, the first aryl insertion is followed by β-H elimination, while the second aryl insertion is terminated by C-H bond formation.

Branching out: redox strategies towards the synthesis of acyclic α-tertiary ethers

Acyclic α-tertiary ethers represent a highly prevalent functionality, common to high-value bioactive molecules, such as pharmaceuticals and natural products, and feature as crucial synthetic handles in their construction. As such their synthesis has become an ever-more important goal in synthetic chemistry as the drawbacks of traditional strong base- and acid-mediated etherifications have become more limiting. In recent years, the generation of highly reactive intermediates via redox approaches has facilitated the synthesis of highly sterically-encumbered ethers and accordingly these strategies have been widely applied in α-tertiary ether synthesis. This review summarises and appraises the state-of-the-art in the application of redox strategies enabling acyclic α-tertiary ether synthesis.

Synthesis of W-Phos Ligand and Its Application in the Copper-Catalyzed Enantioselective Addition of Linear Grignard Reagents to Ketones

The asymmetric catalytic addition of linear Grignard reagents to ketones has been a long-standing challenge in organic synthesis. Herein, a novel family of PNP ligands (W-Phos) was designed and applied in copper-catalyzed asymmetric addition of linear Grignard reagents to aryl alkyl ketones, allowing facile access to versatile chiral tertiary alcohols in good to high yields with excellent enantioselectivities (up to 94 % yield, 96 % ee). The process can also be used to synthesize chiral allylic tertiary alcohols from more challenging α,β-unsaturated ketones. Notably, the potential utility of this method is demonstrated in the gram-scale synthesis and modification of various densely functionalized medicinally relevant molecules.

Organocatalytic discrimination of non-directing aryl and heteroaryl groups: enantioselective synthesis of bioactive indole-containing triarylmethanes

Despite the enormous developments in asymmetric catalysis, the basis for asymmetric induction is largely limited to the spatial interaction between the substrate and catalyst. Consequently, asymmetric discrimination between two sterically similar groups remains a challenge. This is particularly formidable for enantiodifferentiation between two aryl groups without a directing group or electronic manipulation. Here we address this challenge by using a robust organocatalytic system leading to excellent enantioselection between aryl and heteroaryl groups. With versatile 2-indole imine methide as the platform, an excellent combination of a superb chiral phosphoric acid and the optimal hydride source provided efficient access to a range of highly enantioenriched indole-containing triarylmethanes. Control experiments and kinetic studies provided important insights into the mechanism. DFT calculations also indicated that while hydrogen bonding is important for activation, the key interaction for discrimination of the two aryl groups is mainly π-π stacking. Preliminary biological studies also demonstrated the great potential of these triarylmethanes for anticancer and antiviral drug development.