Arenophile-Mediated Dearomative Reduction

Copper-Catalyzed Dearomative 1,2-Hydroamination

Catalytic olefin hydroamination reactions are some of the most atom-economical transformations that bridge readily available starting materials-olefins and high-value-added amines. Despite significant advances in this field over the last two decades, the formal hydroamination of nonactivated aromatic compounds remains an unsolved challenge. Herein, we report the extension of olefin hydroamination to aromatic π-systems by using arenophile-mediated dearomatization and Cu-catalysis to perform 1,2-hydroamination on nonactivated arenes. This strategy was applied to a variety of substituted arenes and heteroarenes to provide general access to structurally complex amines. We conducted DFT calculations to inform mechanistic understanding and rationalize unexpected selectivity trends. Furthermore, we developed a practical, scalable desymmetrization to deliver enantioenriched dearomatized products and enable downstream synthetic applications. We ultimately used this dearomative strategy to efficiently synthesize a collection of densely functionalized small molecules.

Synthetic techniques for thermodynamically disfavoured substituted six-membered rings

Six-membered rings are ubiquitous structural motifs in bioactive compounds and multifunctional materials. Notably, their thermodynamically disfavoured isomers, like disubstituted cyclohexanes featuring one substituent in an equatorial position and the other in an axial position, often exhibit enhanced physical and biological activities in comparison with their opposite isomers. However, the synthesis of thermodynamically disfavoured isomers is, by its nature, challenging, with only a limited number of possible approaches. In this Review, we summarize and compare synthetic methodologies that produce substituted six-membered rings with thermodynamically disfavoured substitution patterns. We place particular emphasis on elucidating the crucial stereoinduction factors within each transformation. Our aim is to stimulate interest in the synthesis of these unique structures, while simultaneously providing synthetic chemists with a guide to approaching this synthetic challenge.

Photochemical dearomative skeletal modifications of heteroaromatics

Dearomatization has emerged as a powerful tool for rapid construction of 3D molecular architectures from simple, abundant, and planar (hetero)arenes. The field has evolved beyond simple dearomatization driven by new synthetic technology development. With the renaissance of photocatalysis and expansion of the activation mode, the last few years have witnessed impressive developments in innovative photochemical dearomatization methodologies, enabling skeletal modifications of dearomatized structures. They offer truly efficient and useful tools for facile construction of highly complex structures, which are viable for natural product synthesis and drug discovery. In this review, we aim to provide a mechanistically insightful overview on these innovations based on the degree of skeletal alteration, categorized into dearomative functionalization and skeletal editing, and to highlight their synthetic utilities.

Recent Advances in Dearomative Partial Reduction of Benzenoid Arenes

Dearomative partial reduction is an extraordinary approach for transforming benzenoid arenes and has been well-known for many decades, as exemplified by the dehydrogenation of Birch reduction and the hydroarylation of Crich addition. Despite its remarkable importance in synthesis, this field has experienced slow progress over the last half-century. However, a revival has been observed with the recent introduction of electrochemical and photochemical methods. In this Minireview, we summarize the recent advancements in dearomative partial reduction of benzenoid arenes, including dihydrogenation, hydroalkylation, arylation, alkenylation, amination, borylation and others. Further, the intriguing utilization of dearomative partial reduction in the synthesis of natural products is also emphasized. It is anticipated that this Minireview will stimulate further progress in arene dearomative transformations.

Regio- and Diastereoselective Annulation of α,β-Unsaturated Aldimines with Alkenes via Allylic C(sp3)-H Activation by Rare-Earth Catalysts

The [3 + 2] or [4 + 2] annulation of α,β-unsaturated aldimines with alkenes via β'- or γ-allylic C(sp3)-H activation is, in principle, an atom-efficient route for the synthesis of five- or six-membered-ring cycloalkylamines, which are important structural motifs in numerous natural products, bioactive molecules, and pharmaceuticals. However, such a transformation has remained undeveloped to date probably due to the lack of suitable catalysts. We report herein for the first time the regio- and diastereoselective [3 + 2] and [4 + 2] annulations of α,β-unsaturated imines with alkenes via allylic C(sp3)-H activation by half-sandwich rare-earth catalysts having different metal ion sizes. The reaction of α-methyl-substituted α,β-unsaturated aldimines with alkenes by a C5Me4SiMe3-ligated scandium catalyst took place in a trans-diastereoselective [3 + 2] annulation fashion via C(sp3)-H activation at the α-methyl group (β'-position), exclusively affording alkylidene-functionalized cyclopentylamines with excellent trans-diastereoselectivity. In contrast, the reaction of β-methyl-substituted α,β-unsaturated aldimines with alkenes by a C5Me5-ligated cerium catalyst proceeded in a cis-diastereoselective [4 + 2] annulation fashion via γ-allylic C(sp3)-H activation, selectively yielding multisubstituted 2-cyclohexenylamines with excellent cis-diastereoselectivity. The mechanistic details of these transformations have been elucidated by deuterium-labeling experiments, kinetic isotope effect studies, and the isolation and transformations of key reaction intermediates. This work offers an efficient and selective protocol for the synthesis of a new family of cycloalkylamine derivatives, featuring 100% atom efficiency, high regio- and diastereoselectivity, broad substrate scope, and an unprecedented reaction mechanism.

Interrupted SNAr-Alkylation Dearomatization

Dearomatizations provide powerful synthetic routes to rapidly assemble substituted carbocycles and heterocycles found in a plethora of bioactive molecules. Harnessing the advantages of dearomatization typically requires vigorous reagents because of the difficulty in disrupting the stable aromatic core. A relatively mild dearomatization strategy is described that employs lithiated nitriles or isocyanides in a simple SNAr-type addition to form σ-complexes that are trapped by alkylation. The dearomatizations are diastereoselective and efficient and rapidly install two new carbon-carbon bonds, one of which is a quaternary center, as well as nitrile, isocyanide, and cyclohexadiene functionalities.

Enantioselective sulfur(VI) fluoride exchange reaction of iminosulfur oxydifluorides

Linkage chemistry and functional molecules derived from the stereogenic sulfur(VI) centre have important applications in organic synthesis, bioconjugation, drug discovery, agrochemicals and polymeric materials. However, existing approaches for the preparation of optically active S(VI)-centred compounds heavily rely on synthetic chiral S(IV) pools, and the reported linkers of S(VI) lack stereocontrol. A modular assembly method, involving sequential ligand exchange at the S(VI) centre with precise control of enantioselectivity, is appealing but remains elusive. Here we report an asymmetric three-dimensional sulfur(VI) fluoride exchange (3D-SuFEx) reaction based on thionyl tetrafluoride gas (SOF4). A key step involves the chiral ligand-induced enantioselective defluorinative substitution of iminosulfur oxydifluorides using organolithium reagents. The resulting optically active sulfonimidoyl fluorides allow for further stereospecific fluoride-exchange by various nucleophiles, thereby establishing a modular platform for the asymmetric SuFEx ligation and the divergent synthesis of optically active S(VI) functional molecules.

Visible Light Mediated Chemoselective Hydroxylation of Benzylic Methylenes

We have developed a metal-free photocatalytic selective hydroxylation of benzylic methylenes to secondary alcohols. This approach utilizes low-cost eosin Y as photocatalyst, O2 as green oxidant, and inexpensive triethylamine as inhibitor for overoxidation. The mild reaction conditions enable the production of secondary alcohols with 56-95% yields, making it a promising and environmental-friendly method for the synthesis of secondary alcohols from benzylic methylenes.

Photoredox-Enabled Dearomative [2π + 2σ] Cycloaddition of Phenols

Dearomative photocycloaddition of monocyclic arenes is an appealing strategy for comprehending the concept of "escape from flatland". This brings the replacement of readily available planar aromatic hydrocarbon units with a 3D fused bicyclic core with sp3-enriched carbon units. Herein, we outline an intermolecular approach for the dearomative photocycloaddition of phenols. In order to circumvent the ground-state aromaticity and to construct conformationally restrained building blocks, bicyclo[1.1.0]butanes were chosen as coupling partners. This dearomative approach renders straightforward access to a bicyclo[2.1.1]hexane unit fused to a cyclic enone moiety, which further contributed as a synthetic linchpin for postmodifications. Mechanistic experiment advocates for a plausible onset from both the reactants, depending on the redox potential.

Diversification of Simple Arenes into Complex (Amino)cyclitols

Highly oxygenated cyclohexanes, including (amino)cyclitols, are featured in natural products possessing a notable range of biological activities. As such, these building blocks are valuable tools for medicinal chemistry. While de novo synthetic strategies have provided access to select compounds, challenges including stereochemical density and complexity have hindered the development of a general approach to (amino)cyclitol structures. This work reports the use of arenophile chemistry to access dearomatized intermediates which are amenable to diverse downstream transformations. Practical guidelines were developed for the synthesis of natural and non-natural (amino)cyclitols from simple arenes through a series of strategic functionalization events.

Synthesis of trifold-labeled versatile reagent [3,5-13 C2 ,4-15 N]4-phenyl-1,2,4-triazoline-3,5-dione

Triazolinediones are an important class of derivatization agents that have found application in various research disciplines. Their unique reactivity often allows precise and selective tagging of relevant molecular scaffolds to facilitate structural elucidation, tracking in biological systems, and stabilization of labile compounds. Recent research efforts mainly focused on the development of novel fluorescent and ionizable or isotopically labeled tags improving the quantification and identification of the parent molecule by suitable analytical methods. However, these concepts often lack the ability to improve properties facilitating the analysis by nuclear magnetic resonance (NMR) spectroscopy. We herein describe the first synthesis of 13 C and 15 N labeled [3,5-13 C2 ,4-15  N]4-phenyl-1,2,4-triazoline-3,5-dione utilizing the Cookson/Zinner-Deucker synthesis of urazoles. The introduced isotopic labels are ideally suited to support the structural elucidation of unknown and complex derivatization mixtures by NMR, thereby exploiting the increased sensitivity of detecting long-range JHC and additional JCC and JCN couplings within the derivatized compounds of interest.

Arene Insertion with Pincer-Supported Molybdenum-Hydrides: Determination of Site Selectivity, Relative Rates, and Arene Complex Formation

The synthesis of phosphino(oxazoline)pyridine-supported molybdenum(0) cycloocta-1,5-diene complexes is described. Exposure of these complexes to dihydrogen in the presence of an arene resulted in insertion of the substrate into the molybdenum hydride bond and afforded the corresponding molybdenum cyclohexadienyl hydrides. For mono- and disubstituted arenes, the site selectivity for insertion of the most substituted bond increases with increasing size of the substituent from methyl to ethyl, iso-propyl, and tert-butyl. In contrast, 1,3,5-trisubstituted arenes underwent insertion with exclusive site selectivity. Relative rates of insertion were determined by competition experiments and established faster insertions for electron-rich arenes. Introduction of electron-withdrawing trifluoromethyl groups on the arene resulted in decreased relative rates of insertion and an increased rate for H2 reductive elimination, favoring formation of the corresponding molybdenum η6-arene complex. Studies on the reductive elimination of the cyclohexadienyl ligand with the hydride enabled the synthesis of an enantioenriched cyclohexa-1,3-diene. This study provides new insights into the ligand requirements for catalytic arene hydrogenation and a new strategy for selective arene reduction.

Formation of Isolable Dearomatized [4 + 2] Cycloadducts from Benzenes, Naphthalenes, and N-Heterocycles Using 1,2-Dihydro-1,2,4,5-tetrazine-3,6-diones as Arenophiles under Visible Light Irradiation

We report that the dearomative [4 + 2] cycloaddition between 1,2-dihydro-1,2,4,5-tetrazine-3,6-diones (TETRADs) and benzenes, naphthalenes, or N-heteroaromatic compounds under visible light irradiation affords the corresponding isolable cycloadducts. Several synthetic transformations including transition-metal-catalyzed allylic substitution reactions using the isolated cycloadducts at room temperature or above were demonstrated. Computational studies revealed that the retro-cycloaddition of the benzene-TETRAD adduct proceeds via an asynchronous concerted mechanism, while that of the benzene-MTAD adduct (MTAD = 4-methyl-1,2,4-triazoline-3,5-dione) proceeds via a synchronous mechanism.

A Reversibly Porous Supramolecular Peptide Framework

The ability to use bio-inspired building blocks in the assembly of novel supramolecular frameworks is at the forefront of an exciting research field. Herein, we present the first polyproline helix to self-assemble into a reversibly porous, crystalline, supramolecular peptide framework (SPF). This framework is assembled from a short oligoproline, adopting the polyproline II conformation, driven by hydrogen-bonding and dispersion interactions. Thermal activation, guest-induced dynamic porosity and enantioselective guest inclusion have been demonstrated for this novel system. The principles of the self-assembly associated with this SPF will be used as a blueprint allowing for the further development of helical peptide linkers in the rational design of SPFs and metal-peptide frameworks.

Dearomatization of aromatic asmic isocyanides to complex cyclohexadienes

A dearomatization-dislocation-coupling cascade rapidly transforms aromatic isocyanides into highly functionalized cyclohexadienes. The facile cascade installs an exceptional degree of molecular complexity: three carbon-carbon bonds, two quaternary stereocenters, and three orthogonal functionalities, a cyclohexadiene, a nitrile, and an isocyanide. The tolerance of arylisocyanides makes the method among the mildest dearomatizations ever reported, typically occurring within minutes at -78 °C. Experimental and computational analyses implicate an electron transfer-initiated mechanism involving an unprecedented isocyanide rearrangement followed by radical-radical anion coupling. The dearomatization is fast, proceeds via a complex cascade mechanism supported by experimental and computational insight, and provides complex, synthetically valuable cyclohexadienes.

Synthesis of allylanilines via scandium-catalysed benzylic C(sp3)-H alkenylation with alkynes

The ortho-selective benzylic C(sp³)-H alkenylation of 2-methyl tertiary anilines with internal alkynes has been achieved for the first time by using a half-sandwich scandium catalyst. This protocol provides a straightforward route for the synthesis of a new family of 2-allylaniline derivatives, featuring broad substrate scope, 100% atom-efficiency, high yields, and high chemo-, regio-, and stereoselectivity.

Bicyclo[2.2.0]hexene derivatives as a proaromatic platform for group transfer and chemical sensing

Here we report the design, preparation, synthetic utility, and sensing application of a class of proaromatic structures, namely bicyclo[2.2.0]hexene (BCH) derivatives. Building on a valence isomerism concept, they feature modular and easy synthesis as well as high thermal stability, and can be oxidatively activated under mild conditions. New alkyl transfer reactions using BCHs as a radical donor have been developed to showcase the utility of their proaromaticity. Moreover, the redox-triggered valence isomerization of a quinoline-derived BCH led to colorimetric and fluorescent responses toward vapors of electrophilic reagents in solution and solid phase, respectively. This optical response was shown to involve a 1,3-cyclohexadiene structure that possesses an intramolecular charge transfer excited state with interesting aggregation induced emission (AIE) character. Thus, the potential of BCHs has been demonstrated as a versatile platform for the development of new reagents and functional materials.

Cyclohexadienes have been widely explored as proaromatic surrogates for group transfer reactions but limited storage stability and difficult accessibility of these compounds limits the application range. Here, the authors present a class of proaromatic bicyclo[2.2.0]hexene derivatives and demonstrate their application in alkyl transfer reactions and sensing applications.

Catalytic three-component C-C bond forming dearomatization of bromoarenes with malonates and diazo compounds

A Pd-catalyzed dearomative three-component C-C bond formation of bromoarenes with diazo compounds and malonates was developed. Various bromoarenes ranging from benzenoids to azines and heteroles were transformed to the corresponding substituted alicyclic molecules. The key to this reaction is the generation of a benzyl-palladium intermediate, which reacts with malonates to form a Pd-O-enolate species. Strikingly, the present method enabled rapid access to multi-substituted alicycles through subsequent elaboration of dearomatized products.

Palladium-catalyzed dearomative 1,4-difunctionalization of naphthalenes

A highly diastereoselective dearomatization of naphthalenes via a Pd-catalyzed 1,4-difunctionalization reaction is described. In the presence of a commercially available palladium precursor and ligand, intramolecular dearomative Heck-type insertion provides π-allylpalladium intermediates which are readily captured by a series of nucleophiles in excellent yields (up to 99%). This reaction features mild conditions, broad substrate scope, and useful transformations of the products.

Chemical Equivalent of Arene Monooxygenases: Dearomative Synthesis of Arene Oxides and Oxepines

Direct epoxidation of aromatic nuclei by cytochrome P450 monooxygenases is one of the major metabolic pathways of arenes in eukaryotes. The resulting arene oxides serve as versatile precursors to phenols, oxepines, or trans-dihydrodiol-based metabolites. Although such compounds have an important biological and chemical relevance, the lack of methods for their production has hampered access to their utility. Herein, we report a general arenophile-based strategy for the dearomative synthesis of arene oxides. The mildness of this method permits access to sensitive monocyclic arene oxides without any noticeable decomposition to phenols. Moreover, this method enables direct conversion of polycyclic arenes and heteroarenes into the corresponding oxepines. Finally, these studies provided direct connection between simple aromatic precursors and complex small organic molecules via arene oxides and oxepines.

Dearomative Allylation of Naphthyl Cyanohydrins by Palladium Catalysis: Catalyst-Enhanced Site Selectivity

A dearomative allylation of naphthyl cyanohydrins with allyl borates and allyl stannanes under palladium catalysis was developed. At the initial stage of this study, the dearomative reaction (C4 substitution of the aromatics) was competing with benzyl substitution. To circumvent this issue, the use of palladium and meta-disubstituted triarylphosphine as the catalyst in a 1:1 ratio was found to enhance the site selectivity, furnishing the desired dearomatized products. Further derivatizations of products were also successful.

Visible-Light-Induced Dearomatizations

The dearomatization of aromatic compounds is an important synthetic strategy used in accessing complex three-dimensional structures from simple aromatic precursors. This minireview aims to provide an overview of recent advancements in this area, with a specific focus on visible-light-mediated dearomative transformations. Compared to the conventional high-energy ultraviolet (UV) light-promoted processes, not only these new approaches offer milder reaction conditions to accommodate wider variety of substrates with sensitive functionalities, but also enable the use of photocatalysts and other promoters, significantly expanding the reaction space. Application of these transformations to the synthesis of bioactive compounds are also discussed.

Selective Arene Hydrogenation for Direct Access to Saturated Carbo- and Heterocycles

Arene hydrogenation provides direct access to saturated carbo- and heterocycles and thus its strategic application may be used to shorten synthetic routes. This powerful transformation is widely applied in industry and is expected to facilitate major breakthroughs in the applied sciences. The ability to overcome aromaticity while controlling diastereo-, enantio-, and chemoselectivity is central to the use of hydrogenation in the preparation of complex molecules. In general, the hydrogenation of multisubstituted arenes yields predominantly the cis isomer. Enantiocontrol is imparted by chiral auxiliaries, Brønsted acids, or transition-metal catalysts. Recent studies have demonstrated that highly chemoselective transformations are possible. Such methods and the underlying strategies are reviewed herein, with an emphasis on synthetically useful examples that employ readily available catalysts.

Light-Stabilized Dynamic Materials

The light-responsive adaptation of polymer materials typically requires different wavelengths or additional heat to induce reversible covalent bond formation and dissociation. Here, we bypass the use of invasive triggers by introducing light-stabilized dynamic materials that can undergo a repeatable change in topology from a covalently cross-linked material into a liquid polymer formulation by switching one visible light source on-and-off without the need for any additional triggers. Specifically, we exploit the photo-Diels-Alder reaction of triazolinediones with naphthalenes as a dynamic covalent cross-linking platform that enables green light-induced network formation, while the cross-linked material collapses through spontaneous cycloreversion upon standing in the dark at ambient temperature. Importantly, the covalent cross-links remain stabilized for as long as visible light is present, thereby retaining the material's structural integrity. This enables their potential use in an array of light-directed applications whereby network properties such as stiffness can be tuned by the mildest trigger of all: darkness.

Synthesis of (±)-Idarubicinone via Global Functionalization of Tetracene

Anthracyclines are archetypal representatives of the tetracyclic type II polyketide natural products that are widely used in cancer chemotherapy. Although the synthesis of this class of compounds has been a subject of several investigations, all known approaches are based on annulations, relying on the union of properly prefunctionalized building blocks. Herein, we describe a conceptually different approach using a polynuclear arene as a starting template, ideally requiring only functional decorations to reach the desired target molecule. Specifically, tetracene was converted to (±)-idarubicinone, the aglycone of the FDA approved anthracycline idarubicin, through the judicious orchestration of Co- and Ru-catalyzed arene oxidation and arenophile-mediated dearomative hydroboration. Such a global functionalization strategy, the combination of site-selective arene and dearomative functionalization, provided the key anthracycline framework in five operations and enabled rapid and controlled access to (±)-idarubicinone.

Iridium-catalyzed 1,5-(aryl)aminomethylation of 1,3-enynes by alkenyl-to-allyl 1,4-iridium(i) migration

A novel multicomponent coupling reaction involving the iridium-catalyzed 1,5-difunctionalization of 1,3-enynes with arylboronic acids and triazinanes is described.

Palladium-Catalyzed Dearomative syn-1,4-Diamination

Herein we report a dearomative syn-1,4-diamination protocol using simple nonactivated arenes and amines. This one-pot method utilizes arene-arenophile para-cycloadducts, formed via visible-light-mediated [4+2]-photocycloaddition that undergoes formal allylic substitution with amine nucleophiles under Pd-catalysis. The products are obtained with exclusive syn-1,4-selectivity; the method permits enantioselective desymmetrization of naphthalene, as well as elaborations of amine-containing drug molecules. Furthermore, the resulting unsaturated products are amenable to numerous options for diversification. Overall, this novel dearomative functionalization strategy offers rapid and straightforward access to complex building blocks, which are difficult to prepare otherwise, from simple arenes.

The High Chemofidelity of Metal-Catalyzed Hydrogen Atom Transfer

The implementation of any chemical reaction in a structurally complex setting ( King , S. M. J. Org. Chem. 2014 , 79 , 8937 ) confronts structurally defined barriers: steric environment, functional group reactivity, product instability, and through-bond electronics. However, there are also practical barriers. Late-stage reactions conducted on small quantities of material are run inevitably at lower than optimal concentrations. Access to late-stage material limits extensive optimization. Impurities from past reactions can interfere, especially with catalytic reactions. Therefore, chemical reactions on which one can rely at the front lines of a complex synthesis campaign emerge from the crucible of total synthesis as robust, dependable, and widely applied. Trost conceptualized "chemoselectivity" as a reagent's selective reaction of one functional group or reactive site in preference to others ( Trost , B. M. Science 1983 , 219 , 245 ). Chemoselectivity and functional group tolerance can be evaluated quickly using robustness screens ( Collins , K. D. Nat. Chem. 2013 , 5 , 597 ). A reaction may also be characterized by its "chemofidelity", that is, its reliable reaction with a functional group in any molecular context. For example, ketone reduction by an electride (dissolving metal conditions) exhibits high chemofidelity but low chemoselectivity: it usually works, but many other functional groups are reduced at similar rates. Conversely, alkene coordination chemistry effected by π Lewis acids can exhibit high chemoselectivity ( Trost , B. M. Science 1983 , 219 , 245 ) but low chemofidelity: it can be highly selective for alkenes but sensitive to the substitution pattern ( Larionov , E. Chem. Commun. 2014 , 50 , 9816 ). In contrast, alkenes undergo reliable, robust, and diverse hydrogen atom transfer reactions from metal hydrides to generate carbon-centered radicals. Although there are many potential applications of this chemistry, its functional group tolerance, high rates, and ease of execution have led to its rapid deployment in complex synthesis campaigns. Its success derives from high chemofidelity, that is, its dependable reactivity in many molecular environments and with many alkene substitution patterns. Metal hydride H atom transfer (MHAT) reactions convert diverse, simple building blocks to more stereochemically and functionally dense products ( Crossley , S. W. M. Chem. Rev. 2016 , 116 , 8912 ). When hydrogen is returned to the metal, MHAT can be considered the radical equivalent of Brønsted acid catalysis-itself a broad reactivity paradigm. This Account summarizes our group's contributions to method development, reagent discovery, and mechanistic interrogation. Our earliest contribution to this area-a stepwise hydrogenation with high chemoselectivity and high chemofidelity-has found application to many problems. More recently, we reported the first examples of dual-catalytic cross-couplings that rely on the merger of MHAT cycles and nickel catalysis. With time, we anticipate that MHAT will become a staple of chemical synthesis.

Recent advances in chemical dearomatization of nonactivated arenes

Dearomatization reactions provide a synthetic connection between readily available, simple aromatic starting materials and more saturated intermediates of greater molecular complexity and synthetic utility. The last decade has witnessed a steady increase in the development of dearomative methods, providing new synthetic approaches to high-value building blocks and natural products. This review highlights advances both in the area of dearomatization methodologies for the most chemically inert arenes and in synthetic applications of such strategies.

Palladium-Catalyzed Dearomative syn-1,4-Carboamination

A dearomative 1,4-carboamination of arenes has been achieved using arenophile cycloaddition and subsequent palladium-catalyzed substitution with nonstabilized lithium enolates. This protocol delivers products with exclusive syn-1,4-selectivity and can be also conducted in an asymmetric fashion. The method allows rapid dearomative difunctionalization of simple aromatic compounds into functional small molecules amenable to further diversification.

Total Synthesis of Lycoricidine and Narciclasine by Chemical Dearomatization of Bromobenzene

The total synthesis of lycoricidine and narciclasine is enabled by an arenophile-mediated dearomative dihydroxylation of bromobenzene. Subsequent transpositive Suzuki coupling and cycloreversion deliver a key biaryl dihydrodiol intermediate, which is rapidly converted into lycoricidine through site-selective syn-1,4-hydroxyamination and deprotection. The total synthesis of narciclasine is accomplished by the late-stage, amide-directed C-H hydroxylation of a lycoricidine intermediate. Moreover, the general applicability of this strategy to access dihydroxylated biphenyls is demonstrated with several examples.

Cyclohexa-1,3-diene-based dihydrogen and hydrosilane surrogates in B(C6F5)3-catalysed transfer processes

Transition-metal-free transfer hydrogenation and transfer hydrosilylation of alkenes are achieved with cyclohexa-1,3-diene-based surrogates.