Direct Deaminative Functionalization

Direct Amination of Anilines Utilizing Dearomatized Phenolate Species

Activation of the aryl C-N bond underpins critical challenges in modern organic synthesis. Herein, the direct amination of anilines is presented via hypervalent iodine-mediated transient dearomatized phenolate intermediates, enabling selective C(aryl)-NH2 bond cleavage under mild conditions. A library of bioactive p-alkylaminophenols is synthesized in up to 85% yields within 3 h. Being used in late-stage drug diversification and mechanistic studies, this protocol offers a modular platform for complex amine construction.

Switchable and Stereospecific C-Glycosylation Strategy via Formal Functional Group Deletion

Carbohydrates constitute an important class of biologically relevant natural products. Among the synthetic glycomimetics, C-glycosides are particularly interesting due to their chemical and metabolic stability toward acidic and enzymatic hydrolysis at the anomeric position. The stereochemical outcomes of traditional methodologies to access C-glycosides rely heavily on substrate control. Herein, we report a novel synthetic strategy to access diverse C-glycosides with precise stereochemical control at the anomeric position via formal functional group deletion, where both α- and β-anomers of furanoses and pyranoses can be obtained as single stereoisomers. Additionally, the broad scope of heterocyclic C-glycosides obtained via this strategy further illustrates its potential for empowering future application in both chemical biology research and drug discovery.

Skeletal Editing of Isoindolines to Tetralins

We present a skeletal editing strategy for transforming isoindolines into tetralins via a cascade N-atom removal deconstruction followed by a Diels-Alder reaction between in situ generated o-quinodimethanes and activated alkenes. This approach features a broad substrate scope, excellent stereoselectivity, and high yields, demonstrating its applicability to complex bioactive compounds and natural products. Notably, case studies showcase the efficient construction of challenging spirocyclic and bridged systems, underscoring the method's versatility and potential for advancing applications in synthetic chemistry.

N-Atom Deletion Involving Rearrangement of Sulfamoyl Azides or Triazanium Salts

ConspectusAmines are frequent structural components in natural products, pharmaceuticals, ligands, and catalysts, making their synthesis and transformation essential to organic chemistry. While C-N bond formation has become a well-established and reliable synthetic strategy, the selective cleavage of C-N bonds remains relatively underexplored. This challenge arises from the low heterolytic nucleofugality of nitrogen, a property that limits the practical application of C-N bond cleavage. This gap underscores a significant area in synthetic methodology in need of further development. In this context, N atom deletion─defined as the selective removal of a nitrogen atom via C-N bond cleavage, while preserving the integrity of the remaining framework─has emerged as a promising approach for skeletal editing. Since Levin's landmark 2021 report, N atom deletion has gained attention for its potential to precisely modify molecular skeletons. Building on the skeletal editing concepts advanced by Levin and Sarpong, particularly their strategies for modifying cyclic frameworks, we recognized the critical need for developing mild and efficient methods that enable the structural manipulation of cyclic systems.This Account summarizes our research since 2017, focusing on two approaches to N atom deletion with distinct mechanisms: the rearrangement of sulfamoyl azides and the conversion of triazanium intermediates. Initially, we explored and optimized the thermal rearrangement of sulfamoyl azides derived from secondary amines, discovering its potential as a viable synthetic strategy for N atom deletion. In 2024, we introduced an O-diphenylphosphinyl hydroxylamine (DPPH)-promoted N atom deletion, involving the generation and novel rearrangement of triazanium intermediates. Both methods enable the conversion of polar aliphatic amines into nonpolar scaffolds and are applicable to both linear molecules and cyclic systems of varying sizes. The DPPH-based approach, in particular, demonstrated exceptional effectiveness for sterically hindered substrates with mild reaction conditions and no need for anhydrous or oxygen-free environments. The mechanisms of two methods─both via isodiazene and radical intermediates─were elucidated through rigorous experimental investigation. Additionally, we observed the rapid formation of hydro(deutero)deamination products when primary amines were exposed to DPPH.Beyond its role as a typical skeletal editing strategy, N atom deletion of secondary amines has emerged as a crucial synthetic approach. Though with limitations, it transforms the challenging task of constructing C-C bonds into a more manageable sequence: the formation of C-N bonds following selective N atom removal. We have applied this strategy in the synthesis of natural products, ligands, hydrocarbon cages, and pharmaceuticals. We hope that this work will stimulate further interest in N atom deletion as a skeletal editing strategy and encourage its incorporation into advanced synthetic methodologies, thereby expanding its utility across diverse areas of organic chemistry.

Photocatalyst-free formate-mediated C-O cleavage by the EDA complex and SCS strategy for the synthesis of diaryl 1,4-diketone in air

Under mild visible light conditions, formates facilitate C-O cleavage via the EDA complex and SCS strategy, yielding α-carbonyl alkyl radicals. These radicals then react with olefins under air conditions, leading to the synthesis of diaryl 1,4-dicarbonyl compounds. Mechanistic studies reveal that α-formyloxy ketone is generated in situ by the reaction between α-brominated acetophenone and formates, followed by the formation of the EDA complex. Additionally, formates also serve as a single-electron reducing reagent in the reaction.

Aliphatic Amines Unlocked for Selective Transformations through Diazotization

While aromatic diazonium salts are important reagents in organic synthesis, 'Diazonium ions generated from ordinary aliphatic primary amines are usually useless for preparative purposes, since they lead to a mixture of products giving not only substitution by any nucleophile present, but also elimination and rearrangements if the substrate permits.'1 In this work, we report that this statement is no longer valid, and it is now possible to control diazotization of aliphatic amines by utilizing isopentyl nitrite in HFIP. This transformation enabled electrophilic aromatic substitution with these highly abundant and commercially available alkyl reagents, as well as transforming them into building blocks typically employed in organic synthesis. The methodology opens an avenue for reactions involving aliphatic amines, even such demanding substrates as amino acids, as a source of carbocations thus expanding the degree of chemical space.

Alkyl bistriflimidate-mediated electrochemical deaminative functionalization

An efficient electrochemical strategy for the deaminative functionalization of alkyl amines has been described. The alkyl bistriflimidates were readily accessed by the treatment of alkyl amines with trifluoromethanesulfonic anhydride and unprecedentedly employed for C-N bond activation. They can be applied to a range of transformations, including borylation, sulfuration, selenation, sulfonation, Additionally, deaminative esterification and amidation can be performed under catalytic base conditions. The protocol features an undivided cell without the use of transition metal- or photo-catalysts and exhibits high conversion and stability in flow reactors.

Redox-Tunable Ring Expansion Enabled By A Single-Component Electrophilic Nitrogen Atom Synthon

Controllable installation of a single nitrogen atom is central to many major goals in skeletal editing, with progress often gated by the availability of an appropriate N-atom source. Here we introduce a novel reagent, termed DNIBX, based on dibenzoazabicycloheptadiene (dbabh), which allows the electrophilic installation of dbabh to organic substrates. When indanone β-ketoesters are aminated by DNIBX, the resulting products undergo divergent ring expansions depending on the mode of activation, producing heterocycles in differing oxidation states under thermal and photochemical conditions. The mechanism of each transformation is discussed, and the different reactivity modes of the indanone-dbabh adducts are compared to other nitrogenous precursors.

Anomeric Amide-Enabled Alkene-Arene and Alkene-Alkene Aminative Coupling

Despite the prominence of C-N bond forming cross-coupling reactions as a strategy to assemble molecular fragments, aminative coupling approaches, in which two fragments are assembled directly at the heteroatom, represents a rarely exploited retrosynthetic strategy. Herein, we report the design, synthesis, and implementation of an anomeric amide reagent capable of promoting highly regioselective aminative alkene-arene and alkene-alkene coupling reactions. This transformation follows a sequence of catalyst-free chloroamination, N-deprotection, and formal nitrene functionalization, all in one-pot. Due to the simplicity of both the protocol and the building blocks required, high-throughput experimentation (HTE) was employed, in combination with a full-scale scope, to rapidly and efficiently explore a wide range of chemical space and determine the limits of reactivity. In addition, alternative reactivity modes from the functionalized intermediates delivered by this protocol demonstrate the divergent nature of this aminative coupling strategy.

Synthesis of Substituted Tetralins via Nitrogen Deletion/Diels-Alder Cascade Reaction

Skeletal editing is an important approach for the modification and diversification of biologically active molecules. The utilization of nitrogen deletion strategies in skeletal editing has recently emerged as a new method for compound modification. Here, we report an unexpected nitrogen deletion in isoindolines. Contrary to the anticipated outcome of cyclobutane formation via intramolecular radical couplings, the nitrogen deletion of isoindoline triggers a Diels-Alder cycloaddition facilitated by the in situ formation of ortho-xylylene to yield tetraline. Inspired by this reaction, we developed a new strategy for synthesizing substituted tetralins, employing isoindoline, nitrogen deletion reagent (anomeric amide), and dienophiles. This methodology demonstrates a new pathway for tetralin synthesis and the modification and diversification of isoindolines.

Mechanistic insights on C(acyl)-N functionalisation mediated by late transition metals

The carboxamide functional group has a privileged role in organic and biological chemistry due to its prevalence and utility across synthetic and natural products. Due to nN → π*CO delocalisation, amides and related functional groups are typically kinetically resistant to degradation. Nonetheless, over the past decade, transition metal catalysis has transformed our ability to utilise molecules featuring C(acyl)-N units as reactants. Alongside the burgeoning catalytic applications ranging from COx utilisation to small molecule synthesis, elucidation of the underlying mechanisms remains a critical ongoing effort. Herein, we aggregate and analyse current understanding of the mechanisms for C(acyl)-N functionalisation of amides and related functional groups with a focus on recent developments involving mechanisms unique to the late transition metals. Discussion is organized around three general mechanistic manifolds: redox-neutral mechanisms, 2e- redox-cycling mechanisms, and mechanisms involving 1e- redox steps. For each class, we focus on reactions that directly involve a transition metal mediator/catalyst in the C(acyl)-N cleavage step. We conclude with an outlook on the outstanding ambiguities and opportunities for innovation.

Supramolecular Modulator Assisted Cryo-Engineered Porous Cu-DNA Nano-Vehicles for Versatile Theranostic Agent Delivery

DNA nanotechnology combines structural design with therapeutic functions via programmable DNA motifs, but faces challenges in drug loading capacity. Herein a pore-engineering strategy is reported to develop a highly porous, universal DNA nano-vehicle through coordination self-assembly, cryo-engineering, and supramolecular chemistry, adapting to diverse cargo loading with desired theranostic agents. Thus, the complex synthesis and compatibility challenges typically associated with switching between different drug carriers are avoided. To this end, Cu2+ and nucleic acid therapeutic G3139 self-assemble into a prefabricated solid nanostructure, which subsequently undergoes ultrafast freezing and sublimation to introduce porosity, forming highly porous Cu-G3139 nanoparticles (CG NPs). The porous CG NPs efficiently accommodate diverse therapeutic molecules, from chemotherapeutics to non-chemotherapeutic agents, facilitated by positively-charged cyclodextrin. As a proof-of-concept, the photosensitizer indocyanine green (ICG) is loaded and coated with tannic acid (TA) to form CICG@TA, enabling remarkable photothermal and fluorescence imaging-guided synergistic tumor ablation. This work represents the first demonstration of sublimation-induced pore formation in metal-DNA hybrid nanoparticles without chemical etching, offering a scalable "plug-and-play" platform for personalized cancer therapy without redesign. This versatile pore-engineering strategy, merging supramolecular chemistry with cryo-engineered porosity, opens up new avenues for efficient, customized multidrug delivery for diverse tumor theranostic applications.

Merging nucleophilic phosphine catalysis and photocatalysis for the rapid assembly of 2-oxabicyclo-[2.1.1]hexane scaffolds from feedstock allyl alcohols

The previously unreported combination of nucleophilic phosphine catalysis and energy transfer catalysis allows for the rapid construction of structurally distinct 2-oxabicyclo[2.1.1]hexanes (2-oxa-BCH) from readily available building blocks with high atom economy. Previous multistep routes to these important phenyl ring bioisosteres have largely depended on the use of bespoke strain-release agents or on multiple post-functionalisation reactions to access structural diversity of the scaffold. In contrast, this cascade reaction allows the medicinal chemist to exploit the breadth of commercial allyl alcohols to synthesise systematically diverse 2-oxa-BCH architectures. Using a combination of polar and radical disconnections in the same reaction flask, every position of the scaffold can be substituted with useful functional handles such as protected amines, esters and alcohols, as well as arenes and alkyl groups. Cyclic allyl alcohols can even be employed to yield single diastereomers of sp3-rich bridged spirocyclic structures. Aromatic groups at the 1-position can be varied to incorporate a plethora of arenes including medicinally relevant heterocycles such as indole, pyrazole and pyridine.

Hydro- and deutero-deamination of primary amines using O-diphenylphosphinylhydroxylamine

While selective defunctionalizations are valuable in organic synthesis, hydrodeamination of primary amines poses challenges. Deuterodeamination, analogous to hydrodeamination, presents even greater difficulties due to its frequently slower deuteration rate, interference by hydrogenation and constraints in deuterated sources. This study introduces a reliable, robust, and scalable hydro- and deuterodeamination method capable of handling various primary amines. Defined by its mild reaction conditions, rapid completion, simplified purification facilitated by water-soluble byproducts, the method leverages deuterium oxide as a deuterium source and employs commercialized O-diphenylphosphinylhydroxylamine for deamination. Applied to a diverse range of biologically active molecules, it has consistently achieved high yields and efficient deuterium incorporation. By synergizing with site-selective C-H functionalization of primary aliphatic amines, our method reveals synthetic strategies utilizing nitrogen atom as a traceless directing group, encompassing deaminative alkylation, 1,1-deuteroalkylation, 1,1-dialkylation, 1,1,1-deuterodialkylation, C-H arylation, and 1,3-deuteroarylation. Emphasizing this innovation, the processes of deaminative degree-controlled deuteration have been developed.

Precision Propargylic Substitution Reaction: Pd-Catalyzed Suzuki-Miyaura Coupling of Nonactivated Propargylamines with Boronic Acids

Palladium-catalyzed Suzuki-Miyaura cross-coupling is an efficient approach for C-C bond construction. Here we report a deaminative Suzuki-Miyaura reaction to achieve chemo- and regioselectivity in the cross-coupling of nonactivated propargylamines with boronic acids, in which methyl propiolate is introduced to promote the cleavage of the C-N bond to form the C-C bond. This method features a wide range of substrates, good functional group tolerance, and ease of operation, providing an alternative approach to accessing valuable propargylated aromatic compounds.

Benzoquinone Ligand-Enabled Ruthenium-Catalyzed Deaminative Coupling of 2-Aminoaryl Aldehydes and Ketones with Branched Amines for Regioselective Synthesis of Quinoline Derivatives

The catalytic system generated in situ from the cationic Ru-H complex [(C6H6)(PCy3)(CO)RuH]+BF4- (1) with 2,3,4,5-tetrachloro-1,2-benzoquinone (L1) was found to be highly effective for promoting the deaminative coupling reaction of 2-aminoaryl aldehydes with branched amines to form 2-substituted quinoline products. The analogous deaminative coupling reaction of 2-aminoaryl ketones with branched amines led to the regioselective formation of 2,4-disubstituted quinoline products. A number of biologically active quinoline derivatives including graveolinine and a triplex DNA intercalator have been synthesized by using the catalytic method.

A Novel Approach of Electrocatalytic Deamination From Aromatic Amide to Diarylimide on Ni-PTFE Modified Electrode

A hydrophobic Ni-PTFE modified electrode has been prepared by constant current and cathodic electroplating with a nickel sheet as substrate in a PTFE suspension. Then the Ni-PTFE modified electrode was used for electroreduction from aromatic amide to diarylimide. The electrochemical characterizations such as cyclic voltammogram, EIS, polarization curves, and electrode stability have been carried out by electrochemical workstation. The structure of the electroreduction product diarylimide was characterized by 1H NMR, FT-IR, MS(Mass Spectrum), and EA(Elemental Analyzer). Based on the hydrophobicity of the electrode, an approach suggested that the phenyl ketone radical may be formed by electroreductive deamination at the cathode. With the construction of C-N bond by the radical coupling, the electrocatalytic reduction may be comprised of a one-electron process including an ECC (Electrochemical-Chemical-Chemical) process. The electroreduction of aromatic amide to diarylimide may be controlled by both charge migration and concentration polarization. Electrocatalytic reduction of aromatic amides on Ni-PTFE modified electrodes is all well conversion ratio.

Photophysics and photochemistry of thermally activated delayed fluorescence emitters based on the multiple resonance effect: transient optical and electron paramagnetic resonance studies

The photochemistry of two representative thermally activated delayed fluorescence (TADF) emitters based on the multiple resonance effect (MRE) (DABNA-1 and DtBuCzB) was studied. No significant TADF was observed in fluid solution, although the compounds have a long-lived triplet state (ca. 30 μs). We found that these planar boron molecules bind with Lewis bases, e.g., 4-dimethylaminopyridine (DMAP) or an N-heterocyclic carbene (NHC). A new blue-shifted absorption band centered at 368 nm was observed for DtBuCzB upon formation of the adduct; however, the fluorescence of the adduct is the same as that of the free DtBuCzB. We propose that photo-dissociation occurs for the DtBuCzB-DMAP adduct, which is confirmed by femtosecond transient absorption spectra, implying that fluorescence originates from DtBuCzB produced by photo-dissociation; the subsequent in situ re-binding was observed with nanosecdon transient absorption spectroscopy. No photo-dissociation was observed for the NHC adduct. Time-resolved electron paramagnetic resonance (TREPR) spectra show that the triplet states of DABNA-1 and DtBuCzB have similar zero field splitting (ZFS) parameters (D = 1450 MHz). Theoretical studies show that the slow ISC is due to small SOC and weak Herzberg-Teller coupling, although the S1/T1 energy gap is small (0.14 eV), which rationalizes the lack of TADF.

Bottom-up Growth of Convex Sphere with Adjustable Cu(0)/Cu(I) Interfaces for Effective C2 Production from CO2 Electroreduction

One challenge confronting the Cu2O catalysts in the electrocatalysis of carbon dioxide reduction reaction (CO2RR) is the reduction of active Cu(I) species, resulting in low selectivity and quick deactivation. In this study, we for the first time introduce a bottom-up growth of convex sphere with adjustable Cu(0)/Cu(I) interfaces (Cux@Cu2O convex spheres). Interestingly, the interfaces are dynamically modulated by varying hydrothermal time, thus regulating the conversion of C1 and C2 products. In particular, the 4 h hydrothermal treatment applied to Cu0.25@Cu2O convex sphere with the favorable Cu(0)/Cu(I) interface results in the highest selectivity for C2 products (90.5 %). In situ Fourier-transform infrared spectroscopy measurements and density functional theory calculations reveal that the Cu(0)/Cu(I) interface lowers the energy barrier for the production of ethylene and ethanol while increasing the coverage of localized *CO adsorbate for increased dimerization. This work establishes a novel approach for transforming the state of valence-sensitive electrocatalysts into high-value energy-related engineering products.

Evidence for Dearomatizing Spirocyclization and Dynamic Effects in the Quasi-stereospecific Nitrogen Deletion of Tetrahydroisoquinolines

Selectivity in organic chemistry is generally presumed to arise from energy differences between competing selectivity-determining transition states. However, in cases where static density functional theory (DFT) fails to reproduce experimental product distributions, dynamic effects can be examined to understand the behavior of more complex reaction systems. Previously, we reported a method for nitrogen deletion of secondary amines which relies on the formation of isodiazene intermediates that subsequently extrude dinitrogen with concomitant C-C bond formation via a caged diradical. Herein, a detailed mechanistic analysis of the nitrogen deletion of 1-aryl-tetrahydroisoquinolines is presented, suggesting that in this system the previously determined diradical mechanism undergoes dynamically controlled partitioning to both the normal 1,5-coupling product and an unexpected spirocyclic dearomatized intermediate, which converges to the expected indane by an unusually facile 1,3-sigmatropic rearrangement. This mechanism is not reproduced by static DFT but is supported by quasi-classical molecular dynamics calculations and unifies several unusual observations in this system, including partial chirality transfer, nonstatistical isotopic scrambling at the ethylene bridge, the isolation of spirocyclic dearomatized species in a related heterocyclic series, and the observation that introduction of an 8-substituent dramatically improves enantiospecificity.

Mechanochemical synthesis of aromatic ketones: pyrylium tetrafluoroborate mediated deaminative arylation of amides

A new method has been introduced that is able to tackle the complexities of N-C(O) activation in amide moieties through utilization of pyrylium tetrafluoroborate in a mechanochemical setting, where amide bonds undergo activation and subsequent conversion to biaryl ketones. Due to the employment of a mechanochemical setting, the reaction conforms to green chemistry principles, offering an environmentally friendly approach to traditional amide derivatization techniques that rely on transition metals to achieve further functionalization.

Unified Approach to Deamination and Deoxygenation Through Isonitrile Hydrodecyanation: A Combined Experimental and Computational Investigation

Herein, we describe a general hydrodefunctionalization protocol of alcohols and amines through a common isonitrile intermediate. To cleave the relatively inert C-NC bond, we leveraged dual hydrogen atom transfer (HAT) and photoredox catalysis to generate a nucleophilic boryl radical, which readily forms an imidoyl radical intermediate from the isonitrile. Rapid β-scission then accomplishes defunctionalization. This method has been applied to the hydrodefunctionalization of both amine and alcohol-containing pharmaceuticals, natural products, and biomolecules. We extended this approach to the reduction of carbonyls and olefins to their saturated counterparts, as well as the hydrodecyanation of alkyl nitriles. Both experimental and computational studies demonstrate a facile β-scission of the imidoyl radical, and reconcile differences in reactivity between nitriles and isonitriles within our protocol.

Facile and efficient transformation of thiols to disulfides via a radical pathway with N-anomeric amide

Radical coupling of thiols is an attractive route for the synthesis of disulfides, but this approach should be promoted by strong oxidants and/or metal salts in combination with additives, which limits its substrate scope and application. In this work, the N-anomeric amide was first found to be able to realize the conversion of thiols to sulfur radicals with high efficiency in the absence of an oxidant or any additives for the synthesis of symmetrical disulfides. The protocol features mild reaction conditions, good functional group tolerance, and moderate to excellent yields.

2-Oxabicyclo[2.1.1]hexanes: Synthesis, Properties, and Validation as Bioisosteres of ortho- and meta-Benzenes

We have developed a general and practical approach towards 2-oxabicyclo[2.1.1]hexanes with two and three exit vectors via an iodocyclization reaction. The obtained compounds have been easily converted into the corresponding building blocks for use in medicinal chemistry. 2-Oxabicyclo[2.1.1]hexanes have been incorporated into the structure of five drugs and three agrochemicals, and validated biologically as bioisosteres of ortho- and meta-benzenes.

Site-Specific Deaminative Trifluoromethylation of Aliphatic Primary Amines

The introduction of trifluoromethyl groups into organic molecules is of paramount importance in modern synthetic chemistry and medicinal chemistry. While methods for constructing C(sp2 )-CF3 bonds have been well established, the advancement of practical and comprehensive approaches for forming C(sp3 )-CF3 bonds remains considerably restricted. In this work, we describe an efficient and site-specific deaminative trifluoromethylation reaction of aliphatic primary amines to afford the corresponding alkyl trifluoromethyl compounds. The reaction proceeds at room temperature with readily accessible N-anomeric amide (Levin's reagent) and bench-stable bpyCu(CF3 )3 (Grushin's reagent, bpy=2,2'-bipyridine) under blue light. The protocol features mild reaction conditions, good functional group tolerance, and moderate to good yields. Remarkably, the method can be applied to the direct, late-stage trifluoromethylation of natural products and bioactive molecules. Experimental mechanistic studies were conducted, and a radical mechanism is proposed, wherein the dual roles of Grushin's reagent have been elucidated.

Photoredox-Catalyzed Generation of Tertiary Anions from Primary Amines via a Radical Polar Crossover

A method for the generation of tertiary carbanions via a deaminative radical-polar crossover is reported using redox active imines from α-tertiary primary amines. A variety of benzylic amines and amino esters can be used in this approach, with the latter engaging in a novel "aza-Reformatsky" reaction. Electronic trends correlate the stability of the resulting carbanion with reaction efficiency. The anions can be trapped with different electrophiles including aldehydes, ketones, imines, Michael acceptors, and H2 O/D2 O. Selective anion formation can be achieved in the presence of another equivalent or more acidic C-H bond in both an inter- and intramolecular fashion. Mechanistic studies suggest the intermediacy of a discrete carbanion intermediate.

Synthesis of dienes from pyrrolidines using skeletal modification

Saturated N-heterocyclic pyrrolidines are common in natural products, medicinal compounds and agrochemicals. However, reconstruction of their skeletal structures creating new chemical space is a challenging task, and limited methods exist for this purpose. In this study, we report a skeletal modification strategy for conversion of polar cyclic pyrrolidines into nonpolar linear dienes through a N-atom removal and deconstruction process. This involves N-sulfonylazidonation followed by rearrangement of the resulting sulfamoyl azide intermediates. This can be an energetically unfavorable process, which involves the formation of active C-C π bonds, the consumption of inert C-N and C-C σ bonds and the destruction of stable five-membered rings, but we have used it here to produce versatile conjugated and nonconjugated dienes with links of varying lengths. We also studied the application of this method in late-stage skeletal modification of bioactive compounds, formal traceless C(sp2)-H functionalization and formal N-atom deletion.

Azetidine synthesis by La(OTf)3-catalyzed intramolecular regioselective aminolysis of cis-3,4-epoxy amines

Azetidine is a prevalent structural motif found in various biologically active compounds. In this research paper, we report La(OTf)3-catalyzed intramolecular regioselective aminolysis of cis-3,4-epoxy amines to afford azetidines. This reaction proceeded in high yields even in the presence of acid-sensitive and Lewis basic functional groups.

Visible-Light Photoredox-Catalyzed Divergent 1,2-Diacylation and Hydroacylation of Alkenes with Carboxylic Acid Anhydride

A photoredox-catalyzed divergent 1,2-dicarbonylation and hydroacylation of alkenes with acid anhydride is presented. This approach offers a mild and efficient entry to 1,4-dicarbonyl compounds bearing all-carbon quaternary centers, exhibiting a broad substrate scope and high functional group compatibility. Hydrocarbonylaltion of alkenes can also be realized by simply introducing a proton source to the reaction system. Mechanism investigations support a radical addition/radical-polar crossover cascade.

Harnessing Sulfur(VI) Fluoride Exchange Click Chemistry and Photocatalysis for Deaminative Benzylic Arylation

While among the most common functional handles present in organic molecules, amines are a widely underutilized linchpin for C-C bond formation. To facilitate C-N bond cleavage, large activating groups are typically used but result in the generation of stoichiometric amounts of organic waste. Herein, we report an atom-economic activation of benzylic primary amines relying on the Sulfur(VI) Fluoride Exchange (SuFEx) click chemistry and the aza-Ramberg-Bäcklund reaction. This two-step sequence allows the high-yielding generation of 1,2-dialkyldiazenes from primary amines via loss of SO2. Excitation of the diazenes with blue light and an Ir photocatalyst affords radical pairs upon expulsion of N2, which can be coaxed into the formation of C(sp3)-C(sp2) bonds upon diffusion and capture by a Ni catalyst. This arylative strategy relying on a traceless click approach was harnessed in a variety of examples and its mechanism was investigated.

Deaminative bromination, chlorination, and iodination of primary amines

The primary amino group has been seldom utilized as a transformable functionality in organic synthesis. Reported herein is a deaminative halogenation of primary amines using N-anomeric amide as the nitrogen-deletion reagent. Both aliphatic and aromatic amines are competent substrates for direct halogenations. The mildness and robustness of the protocol are evidenced by the successful reactions of several complex- and functional group-enriched bioactive compounds or drugs. Elaboration of the resulting products provides interesting analogues of drug molecules.