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Purpose: This study was motivated by the need for better positron emission tomography (PET)-compatible tools to image bacterial infection. Our previous efforts have targeted bacteria-specific metabolism via assimilation of carbon-11 labeled d-amino acids into the bacterial cell wall. Since the chemical determinants of this incorporation are not fully understood, we sought a high-throughput method to label d-amino acid derived structures with fluorine-18. Our strategy employed a chemical biology approach, whereby an azide (-N3) bearing d-amino acid is incorporated into peptidoglycan muropeptides, with subsequent "click" cycloaddition with an 18F-labeled strained cyclooctyne partner. Procedures: A water-soluble, 18F-labeled and dibenzocyclooctyne (DBCO)-derived radiotracer ([18F]FB-sulfo-DBCO) was synthesized. This tracer was incubated with pathogenic bacteria treated with azide-bearing d-amino acids, and incorporated 18F was determined via gamma counting. In vitro uptake in bacteria previously treated with azide-modified d-amino acids was compared to that in cultures treated with amino acid controls. The biodistribution of [18F]FB-sulfo-DBCO was studied in a cohort of healthy mice with implications for future in vivo imaging. Results: The new strain-promoted azide-alkyne cycloaddition (SPAAC) radiotracer [18F]FB-sulfo-DBCO was synthesized with high radiochemical yield and purity via N-succinimidyl 4-[18F]fluorobenzoate ([18F]SFB). Accumulation of [18F]FB-sulfo-DBCO was significantly higher in several bacteria treated with azide-modified d-amino acids than in controls; for example, we observed 7 times greater [18F]FB-sulfo-DBCO ligation in Staphylococcus aureus cultures incubated with 3-azido-d-alanine versus those incubated with d-alanine. Conclusions: The SPAAC radiotracer [18F]FB-sulfo-DBCO was validated in vitro via metabolic labeling of azide-bearing peptidoglycan muropeptides. d-Amino acid-derived PET radiotracers may be more efficiently screened via [18F]FB-sulfo-DBCO modification.

The breasts undergo marked physiologic changes during lactation that can make conventional imaging evaluation with mammography and US challenging. MRI can be a valuable diagnostic aid to differentiate physiologic and benign processes from malignancy in patients who are lactating. In addition, MRI may allow more accurate delineation of disease involvement than does conventional imaging and assists in locoregional staging, screening of the contralateral breast, assessment of response to neoadjuvant chemotherapy, and surgical planning. Although the American College of Radiology recommends against patients undergoing contrast-enhanced MRI during pregnancy because of fetal safety concerns, contrast-enhanced MRI is safe during lactation. As more women delay childbearing, the incidence of pregnancy-associated breast cancer (PABC) and breast cancer in lactating women beyond the 1st year after pregnancy is increasing. Thus, MRI is increasingly being performed in lactating women for diagnostic evaluation and screening of patients at high risk. PABC is associated with a worse prognosis than that of non-PABCs, with delays in diagnosis contributing to an increased likelihood of advanced-stage disease at diagnosis. Familiarity with the MRI features of the lactating breast and the appearance of various pathologic conditions is essential to avoid diagnostic pitfalls and prevent delays in cancer diagnosis and treatment. The authors review clinical indications for breast MRI during lactation, describe characteristic features of the lactating breast at MRI, and compare MRI features of a spectrum of benign and malignant breast abnormalities. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material. See the invited commentary by Chikarmane in this issue.

Understanding metabolic heterogeneity is the key to uncovering the underlying mechanisms of metabolic-related diseases. Current metabolic imaging studies suffer from limitations including low resolution and specificity, and the model systems utilized often lack human relevance. Here, we present a single-cell metabolic imaging platform to enable direct imaging of lipid metabolism with high specificity in various human-derived 2D and 3D culture systems. Through the incorporation of an azide-tagged infrared probe, selective detection of newly synthesized lipids in cells and tissue became possible, while simultaneous fluorescence imaging enabled cell-type identification in complex tissues. In proof-of-concept experiments, newly synthesized lipids were directly visualized in human-relevant model systems among different cell types, mutation status, differentiation stages, and over time. We identified upregulated lipid metabolism in progranulin-knockdown human induced pluripotent stem cells and in their differentiated microglia cells. Furthermore, we observed that neurons in brain organoids exhibited a significantly lower lipid metabolism compared to astrocytes.

The utilization of calcium carbide as an acetylide specie was an increasing concern in chemical society. Under transition metal‐ and base free conditions, calcium carbide was successfully proved as the acetylide resource to synthesize 1‐monosubstituted‐1,2,3‐triazoles from nucleophilic addition with azides. In this reaction, aryl azides achieved corresponding 1,2,3‐triazoles in good to excellent yields, and a gram‐scale reaction of phenyl azide with calcium carbide was conducted with an excellent yield. Alkyl azides could also participate in the reaction to prepare corresponding 1,2,3‐triazoles with moderate yield. Calcium acetylide hydroxide Ca(OH)C≡CH might be the critical intermediate. The process provided a green and sustainable prospect to utilize calcium carbide resource. [ABSTRACT FROM AUTHOR]

Site‐selective amination of N‐heterocycles is an interesting topic in organic synthesis and drug discovery. We herein present a method for the vicarious‐type nucleophilic amination of azine N‐oxides and cyclic iminoamides using iminyl anions, readily generated from organic azides under basic conditions. The plausible reaction mechanism involving nucleophilic aromatic substitution by iminyl anions is elucidated by a series of mechanistic investigations. [ABSTRACT FROM AUTHOR]

Two new C,O-bidentate chelating triazolylidene-phenolate ligands were synthesized that feature a diisopropylphenyl (dipp) and an adamantyl (Ad) substituent respectively on the triazole scaffold. Subsequent metalation afforded iron(II) complexes [Fe(C^O)2] that are active catalysts for the intramolecular C-H amination of organic azides. When compared to the parent complex containing a triazolylidene with a mesityl substituent (Mes) the increased steric bulk led to slightly lower activity (TOFmax = 23 h-1 vs. 30 h-1), however selectivity towards pyrrolidine formation increases from 92% up to >99%. Kinetic studies indicate that the mechanism is similar in all three complexes and includes a half-order dependence in [Fe(C^O)2], congruent with the involvement of a dimetallic catalyst resting state within this catalyst class. Structural analysis suggests that enhanced bulkiness disfavors N2 loss and nitrene formation, yet shields the nitrene from intermolecular processes and thus favors intramolecular nitrene insertion into the C-H bond. This model rationalizes the high selectivity and the lower reaction rate observed with dipp and with Ad substituents on the ligand. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Unsymmetrical diarylamines are crucial components in many pharmaceuticals and functional materials. In this study, we introduce an efficient Chan‐Lam cross‐coupling method that utilizes phenylboronic acids and aryl azides as coupling agents in a redox‐neutral environment, enabled by a synergistic nickel/photoredox catalytic system. This approach leverages a proton‐coupled electron transfer mechanism to bypass the typical nitrene pathway associated with aryl azides, which is prone to intramolecular rearrangement, C—H amination, and reductive hydrogenation. Notably, our method exhibits broad compatibility with a variety of functional groups, including those derived from pharmaceuticals, demonstrating its versatile potential in organic synthesis and drug modification. [ABSTRACT FROM AUTHOR]

We have devised a single pot, low-cost method to add azide groups to unmodified nucleic acids without the need for enzymes or chemically modified nucleoside triphosphates. This involves reacting an azide-containing sulfinate salt with the nucleic acid, leading to replacement of C-H bonds on the nucleobase aromatic rings with C-R, where R is the azide-containing linker derived from the original sulfinate salt. With the addition of azide functional groups, the modified nucleic acid can easily be reacted with any alkyne-labeled compound of interest, including fluorescent dyes as shown in this work. This methodology enables the fluorescent labeling of a wide variety of nucleic acids, including natively folded RNAs, under mild conditions with minimal effects upon biochemical function and ribozyme catalysis. To demonstrate this, we show that a pair of labeled complementary ssDNA oligonucleotides (oligos) can hybridize to form dsDNA, even when labeled with multiple fluorophores per oligo. In addition, we also demonstrate that two different group II introns can splice when prelabeled internally with fluorophores, using our method. Broadly, this demonstrates that sulfinate modification of RNA is compatible with ribozyme function and Watson-Crick pairing, while preserving the labile backbone.

Extended conjugation has been introduced into boroles but only on the 2,3- or 4,5-positions of the central BC4 core. In this work we synthesize phenanthrylboroles that also have conjugation on the 3,4-positions and demonstrate their insertion reactivity with azides to furnish B,N-analogues of pyrene. [ABSTRACT FROM AUTHOR]

Hydrogels are of interest for a wide range of applications. The ability to control when the hydrogel degrades can provide beneficial properties such as controlled degradation in the environment or the stimulated release of drugs or cells. Self‐immolative polymers are a class of degradable polymers that undergo complete end‐to‐end depolymerization upon the application of a stimulus. They have been explored for hydrogel development, but the ability to prepare and selectively degrade self‐immolative hydrogels under neutral aqueous conditions has so far been limited. We describe here the preparation of water‐soluble polyglyoxylamides with cross‐linkable pendent azides and their cross‐linking to form hydrogels with 4‐arm poly(ethylene glycol)s having unstrained and strained alkynes using copper‐assisted and strain‐promoted azide‐alkyne click chemistry respectively. The influence of pendent azide density and solution polymer content on the resulting hydrogels was evaluated. A polyglyoxylamide with a 70 : 30 ratio of pendent hydroxyl:azide successfully provided hydrogels with compressive moduli ranging from 1.3–6.3 kPa under copper‐free conditions at 10–20 % (w/w) of polymer in phosphate‐buffered saline. Selective depolymerization and degradation of the hydrogels upon irradiation with light was demonstrated, resulting in reductions in the compressive moduli and the release of depolymerization products that were detected by NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The photolytic or oxidative liberation of a cyclic (amino)(alkyl)carbene (CAAC)-stabilized arylborylene in the presence of organoazides yielded borylene-organoazide complexes (4a,b) has been achieved in a manner akin to the first step of the Staudinger reaction. Similarly, a CAAC-stabilized aminoborylene also afforded borylene-organoazide complexes (6a–c), which further undergo rearrangement to produce aminoborane triazene species (7a,b). [ABSTRACT FROM AUTHOR]

An efficient triple-click assembly using a newly designed trivalent platform is disclosed. We achieved the selective azaylide formation of 2,3,5,6-tetrafluorophenyl azides with o-ester-substituted triarylphosphines leaving 2,6-dichlorophenyl azides untouched. Further rapid Staudinger reaction of dichlorophenyl azides and subsequent triazole formation allowed us to prepare trifunctionalized molecules in three steps. [ABSTRACT FROM AUTHOR]

Azide-containing compounds, organic azides, showcases a variety of reactivities, making them highly convenient and chameleonic intermediates. An indoline derivative has been proven to be of great significance in drug discovery due to its sp3-rich property. In this context, it is interesting to perform such vigorous azidation on medicinal-relevant indoles/indolines, resulting in the production of sp3-rich azidoindolines. The potential biological activity, in combination with the sp3-rich indoline bearing the azido moiety, makes azidoindolines an attractive synthetic target for medicinal and synthetic chemists. This review describes recent advances in the synthesis and application of azidoindolines: (1) iodine-mediated azidations, (2) metal-catalyzed azidations, (3) electrochemical azidations, (4) photochemical azidations, (5) azidation using a combination of an oxidant and an azide source, and (6) nucleophilic azidation. [ABSTRACT FROM AUTHOR]

The intramolecular [3 + 2] cycloaddition (IM32CA) reactions of azides and diazoalkanes leading to fused tricyclic 1,2,3-triazolines and 1-pyrazolines have been studied at the MPWB1K/6-311G(d,p) computational level within the molecular electron density theory (MEDT). The IM32CA reactions of azides are classified as zw- type following non-concerted one-step mechanism with earlier N1-C5 bond formation implied from the bonding evolution theory (BET) study with the Gibbs free activation energies between 26.3–30.0 kcal mol−1 at 298 K in benzene while that of the diazoalkanes are classified as pmr- type with the earlier C3-C5 bond formation and Gibbs free activation energies between 24.7–29.1 kcal mol−1 at 298 K in n-pentane. The influence of substituent effects on these IM32CA reactions is studied. Azide reactions with minimal global electron density transfer (GEDT) are classified as the null electron density flux (NEDF) while that of the diazoalkanes are classified as forward electron density flux (FEDF). QTAIM analysis and ELF study allow revealing the non-covalent interactions at the TSs. [ABSTRACT FROM AUTHOR]

Metal azides are highly energetic materials that release a large amount of gas upon detonation. They also release metal particles, generating an aerosol. The most common azide is sodium azide (NaN3), which is used nowadays in car airbags. If the decomposition is not complete, harmful azide particles might be inhaled. Heavy metal azides find application as a primary explosive (primer) in ammunition. Public health officials have raised concerns about heavy metal particles released during training in shooting ranges. We identify a lack of knowledge on airborne metal particles properties released from azide detonation and on the analytical methods applied to characterize them. As a case study, we detonated milligram amounts of silver azide, copper azide, and a mixture of them in a glove box. We then analyse the airborne particles with an ensemble analytical setup, able to measure real-time their particle size distribution and chemical composition. We detected spherical metal nanoparticles in the range of 2–500 nm. These findings and the developed analytical tools may allow identifying airborne nanoparticles the passenger compartments of vehicles after airbag activation as well as in indoor shooting ranges, contributing to the evaluation of public health risks. [ABSTRACT FROM AUTHOR]

Diazo compounds and organic azides are widely used as reagents for accessing valuable molecules in multiple areas of fundamental and applied chemistry. Their capacity to undergo versatile chemical transformations arises from the reactive nature of an incipient dinitrogen molecule at the terminal position. In this work, we report the synthesis and characterization of an N-heterocyclic carbene (NHC)– stabilized diazoborane—a boron-centered analog of organic azides and diazoalkanes. The diazoborane displays a strong tendency to release dinitrogen, thus serving as a borylene source, in analogy to organic azides and diazoalkanes serving as nitrene and carbene sources, respectively. Also reminiscent of diazoalkane and organic azide reactivity, the diazoborane serves as a 1,3-dipole that undergoes uncatalyzed [3+2] cycloaddition with an unactivated terminal alkyne, affording a five-membered heterocycle after a two-step rearrangement. [ABSTRACT FROM AUTHOR]

Precise modification of a chemical site in a molecule at the single-atom level is one of the most elegant yet difficult transformations in chemistry. A reagent specifically designed for chemoselective introduction of monoatomic carbon is a particularly formidable challenge. Here, we report a straightforward, azide-free synthesis of a crystalline and isolable diazophosphorus ylide, Ph3PCN2, a stable compound with a carbon atom bonded to two chemically labile groups, triphenylphosphine (PPh3) and dinitrogen (N2). Without any additives, the diazophosphorus ylide serves as a highly selective transfer reagent for fragments, including Ph3PC, to deliver phosphorus ylide–terminated heterocumulenes and CN2 to produce multisubstituted pyrazoles. Ultimately, even exclusive carbon-atom transfer is possible. In reactions with aldehydes and acyclic and cyclic ketones (R2C=O), the carbon-atom substitution forms a vinylidene (R2C=C:) en route to alkynes or butatrienes. [ABSTRACT FROM AUTHOR]

A chiral tetra-NHC iron(II) complex and its disparate reactivity with multiple organic azides is reported. Both aryl and alkyl azides react with the iron(II) complex yielding three distinct products: an iron(IV) imide, an iron(IV) tetrazene, and a surprising and unprecedented double imide insertion complex. [ABSTRACT FROM AUTHOR]

An efficient chromoselective photochemical process is presented for the synthesis of 2H‐azirines and 1,3‐diazabicylo[3.1.0]hex‐3‐enes from readily available vinyl azides. The method exploits continuous flow photochemistry to enable the safe consumption of the hazardous azide group and provides uniform irradiation using high‐power LEDs at 365–450 nm. Additionally, a scaled telescoped process has been developed providing access to drug‐like 1,6‐dihydropyrimidines and pyrimidines via integrated ring‐expansion and oxidation reactions. Given the prevalence of various azacyclic targets in pharmaceutical, agrochemical and materials applications it is anticipated that this methodology will enable further exploitations of these important scaffolds. [ABSTRACT FROM AUTHOR]

Reactivity and regioselectivity of SNAr‐type fluorine substitution with azide in polyfluorosubstituted nitrobenzenes was studied both theoretically and experimentally. The obtained polyazido‐substituted nitrobenzene derivatives were extensively characterized by NMR, IR, HPLC, X‐ray, and DFT methods. It was found that the substitution with the azide nucleophile occurs first at the para‐ and the ortho‐positions to the NO2‐group and that transazidation reactions also occur here. Thermal decomposition of prepared azidonitrobenzenes was studied both in controlled (kinetic decay) and uncontrolled (explosion) modes. In case of the controlled thermal decomposition of ortho‐azidonitrobenzenes, benzofuroxans were found as major products of the reaction unless another azido group was adjacent to the furoxan moiety. The bursting power of azidonitrobenzenes was found to rise gradually with the number of the azide substituents in the aromatic ring. [ABSTRACT FROM AUTHOR]

α‐Azidochalcones have emerged as remarkably versatile precursors within organic azides, showcasing a broad spectrum of reactivity as a cornerstone for synthesizing diverse molecular scaffolds. The ongoing progress in this field has opened new opportunities for constructing complex organic molecules through diverse chemical transformations due to the versatile reactivity of α‐azidochalcones for further functionalization. The comprehensive review presented herein provides a concise yet detailed examination of the synthesis, reactivity, and potential applications of α‐azidochalcones. Focusing on both thermal and photochemical pathways, this review highlights the versatility of α‐azidochalcones as pivotal precursors in the synthesis of various heterocyclic frameworks. [ABSTRACT FROM AUTHOR]

Nucleophilic ring-opening of 1,6,10,14-tetraoxatetraspiro[2.1.25.1.29.1.213.13]hexadecane, a cyclooctane structure spiro-fused with four oxirane fragments, under the action of sodium azide was studied. Depending on the relative configuration of stereocenters in the starting compound, the reaction proceeded as an intramolecular transannular cyclization with the formation of a 9-oxabicyclo[3.3.1]nonane skeleton or as an independent nucleophilic opening of the oxirane rings, leading to tetraazido tetraols of the cyclooctane series. [ABSTRACT FROM AUTHOR]

Despite their critical importance in drug development and biochemistry, efficiently synthesizing α-glycosyl azides has continued to pose significant challenges. In this report, we introduce a universal and practical radical reaction for the stereoselective synthesis of α-glycosyl azides using bench-stable allyl glycosyl sulfones as the donor. This method is characterized by its mild reaction conditions, high stereoselectivity, and extensive scope of glycosyl units. Moreover, the accessibility of several structurally complex drug–sugar conjugates underscores the practicality of our approach. [ABSTRACT FROM AUTHOR]

Carbamoyl azide is a pivotal compound used in the transformation into urea and amines, as well as in nitrene insertion reactions. In this study, we present a pioneering method for synthesizing carbamoyl azide directly from acid redox active esters without the use of metals or oxidants. This approach demonstrates tolerance for various functional groups, enhancing its applicability. Furthermore, this technique facilitates late‐stage modifications of natural products and pharmaceuticals, thereby accelerating the development and identification of novel drug candidates. [ABSTRACT FROM AUTHOR]

In recent years, researchers have often encountered the significance of the aberrant metabolism of tumor cells in the pathogenesis of malignant neoplasms. This phenomenon, known as the Warburg effect, provides a number of advantages in the survival of neoplastic cells, and its application is considered a potential strategy in the search for antitumor agents. With the aim of developing a promising platform for designing antitumor therapeutics, we synthesized a library of conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones. To gain insight into the determinants of the biological activity of the prepared compounds, we showed that the conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones, which are cytotoxic agents, demonstrate selective activity toward a number of tumor cell lines with glycolysis-inhibiting ability. Moreover, the results of molecular and in silico screening allowed us to identify these compounds as potential inhibitors of the pyruvate kinase M2 oncoprotein, which is the rate-determining enzyme of glycolysis. Thus, the results of our work indicate that the synthesized conjugates of 3,5-bis(arylidene)-4-piperidone and sesquiterpene lactones can be considered a promising platform for designing selective cytotoxic agents against the glycolysis process, which opens new possibilities for researchers involved in the search for antitumor therapeutics among compounds containing piperidone platforms. [ABSTRACT FROM AUTHOR]

A new strategy for N-borylenamines by reaction of 2-alkynyl benzyl azides with B(C6F5)3 was developed. This novel 1,3-carboboration reaction proceeded via a 5-exo-dig cyclization/formal 1,1-carboboration/ B(C6F5)2 shift reaction sequence. Additionally, N-borylenamines can undergo hetero Diels–Alder (HDA) reactions with a variety of dienophiles. Our results are an attractive complement to HDA reactions. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed conditions for diazidation or acetoxy/hydroxylation of N‐allyl sulfonamides by using Pd(OAc)2 as the catalyst combined with Mn(OAc)3 ⋅ 2H2O have been developed. The 1,2‐diazidation reaction of the carbon‐carbon double bond occurs in mild conditions (i. e. NaN3 as azide source in THF at room temperature), whereas the 1,2‐acetoxy/hydroxylation requires an excess of Mn(OAc)3 ⋅ 2H2O. The well‐known ability of this reagent to act through single‐electron transfer (SET) makes plausible a radical mechanism involving high valent palladium complexes. [ABSTRACT FROM AUTHOR]

Chiral 1,2,3-triazoles are highly attractive motifs in various fields. However, achieving catalytic asymmetric click reactions of azides and alkynes for chiral triazole synthesis remains a significant challenge, mainly due to the limited catalytic systems and substrate scope. Herein, we report an enantioselective azidation/click cascade reaction of N-propargyl-β-ketoamides with a readily available and potent azido transfer reagent via copper catalysis, which affords a variety of chiral 1,2,3-triazoles with up to 99% yield and 95% ee under mild conditions. Notably, chiral 1,5-disubstituted triazoles that have not been accessed by previous asymmetric click reactions are also prepared with good functional group tolerance. Catalytic asymmetric click reactions of azides and alkynes for chiral triazole synthesis remains a challenge, due to the limited catalytic systems and substrate scope. Herein, the authors report the enantioselective azidation/click cascade reaction of N-propargyl-β-ketoamides via copper catalysis, affording a variety of chiral 1,2,3-triazoles. [ABSTRACT FROM AUTHOR]

1,3-Alternate calix[4]arenes were prepared, having bulky adamantyl groups in the p-positions of all four aromatic units of the macrocycles and pairs of propargyl or 2-azidoethyl groups alternating with n-propyl groups at the phenol oxygen atoms. The step-wise syntheses were carried out through a selective distal alkylation of the parent p-adamantylcalix[4]arene with propargyl bromide or 1,2-dibromoethane, resulting in calix[4]arenes bearing pairs of propargyl or 2-bromoethyl groups at their narrow rims. The bromine atoms were replaced by azide groups, and then both calix[4]arene diethers were exhaustively alkylated at the remaining OH-groups with 1-iodopropane under stereoselective conditions to fix the macrocycles in an 1,3-alternate shape. The structures of the prepared p-adamantylcalix[4]arenes were confirmed by NMR and HRMS data, and, for the 1,3-alternate dipropargyl ether, the X-ray diffraction data were also collected. Preliminary data on the reactivity of the prepared calixarenes under the CuAAC conditions suggested a strong steric hampering created by the adamantane units nearby the reacting alkyne or azide groups that affected the outcome of the two-fold cycloaddition involving the calixarene bis(azides) or bis(alkynes) as complementary partners. [ABSTRACT FROM AUTHOR]

[Display omitted] New azidomethyl-substituted 7-azacoumarin-3-carbox- amides were converted into the corresponding 1,2,3-triazole hybrids by the copper-catalyzed click reaction with phenyl- acetylene. Cytotoxicity and antimicrobial activity were evaluated, and leading compounds were identified. [ABSTRACT FROM AUTHOR]

ContextThe azide anion (N3-) is highly toxic. It exists most commonly as sodium azide, which is used widely and is readily available, raising the potential for occupational incidents and use as a weapon of mass destruction. Azide-poisoned patients present with vomiting, seizures, hypotension, metabolic acidosis, and coma; death can occur. No specific azide antidote exists, with treatment being solely supportive. Azide inhibits mitochondrial cytochrome c oxidase and is likely oxidized to nitric oxide in vivo. Cytochrome c oxidase inhibition depletes intracellular adenosine triphosphate and increases oxidative stress, while increased nitric oxide causes hypotension and exacerbates oxidative damage. Here, we tested whether the cobalamin (vitamin B12) analog cobinamide, a strong and versatile antioxidant that also neutralizes nitric oxide, can reverse azide toxicity in mammalian cells, Drosophila melanogaster, and mice.ResultsWe found cobinamide bound azide with a moderate affinity (Ka 2.87 × 105 M-1). Yet, cobinamide improved growth, increased intracellular adenosine triphosphate, and reduced apoptosis and malondialdehyde, a marker of oxidative stress, in azide-exposed cells. Cobinamide rescued Drosophila melanogaster and mice from lethal exposure to azide and was more effective than hydroxocobalamin. Azide likely generated nitric oxide in the mice, as evidenced by increased serum nitrite and nitrate, and reduced blood pressure and peripheral body temperature in the animals; the reduced temperature was likely due to reflex vasoconstriction in response to the hypotension. Cobinamide improved recovery of both blood pressure and body temperature.ConclusionWe conclude cobinamide likely acted by neutralizing both oxidative stress and nitric oxide, and that it should be given further consideration as an azide antidote.

New protein synthesis is regulated both at the level of mRNA transcription and translation. RNA-Seq is effective at measuring levels of mRNA expression, but techniques to monitor mRNA translation are much more limited. Previously, we reported results from O-propargyl-puromycin (OPP) labeling of proteins undergoing active translation in a 2-h time frame, followed by biotinylation using click chemistry, affinity purification, and on-bead digestion to identify nascent proteins by mass spectrometry (OPP-ID). As with any on-bead digestion protocol, the problem of nonspecific binders complicated the rigorous categorization of nascent proteins by OPP-ID. Here, we incorporate a chemically cleavable linker, Dde biotin-azide, into the protocol (OPP-IDCL) to provide specific release of modified proteins from the streptavidin beads. Following capture, the Dde moiety is readily cleaved with 2% hydrazine, releasing nascent polypeptides bearing OPP plus a residual C3H8N4 tag. When results are compared side by side with the original OPP-ID method, change to a cleavable linker led to a dramatic reduction in the number of background proteins detected in controls and a concomitant increase in the number of proteins that could be characterized as newly synthesized. We evaluated the method's ability to detect nascent proteins at various submilligram protein input levels and showed that, when starting with only 100 μg of protein, ∼1500 nascent proteins could be identified with low background. Upon treatment of K562 cells with MLN128, a potent inhibitor of the mammalian target of rapamycin, prior to OPP treatment, we identified 1915 nascent proteins, the majority of which were downregulated upon inhibitor treatment. Repressed proteins with log2 FC

A simple method for the preparation of N-phenylbenzamides from azidobenzenes and 1,3-diphenylpropane-1,3-diones is described. In this reaction, N-phenylbenzamides were generated by [3+2] cycloaddition and intramolecular ring opening. The products were afforded in yields of 35–84% under mild conditions. [ABSTRACT FROM AUTHOR]

Visible-light-induced [3+2] cyclization of vinyl azides with perfluoroalkyl-substituted imidoyl sulfoxonium ylides has been developed for the first time. In this transformation, perfluoroalkyl-substituted imidoyl sulfoxonium ylides are firstly employed as a carbon radical precursor under visible light irradiation, providing a new and efficient method for the construction of perfluoroalkyl-substituted 1-pyrrolines. [ABSTRACT FROM AUTHOR]

In chemical reactions of copper(II) acetate dihydrate with imidazolium azide salts in ethanol solution several new homoleptic azidocuprates(II) were obtained. In dependency of the used counter cation various different azidocuprate moieties were crystalized. The doubly charged DMMDIm2+ cation facilitates the formation of mononuclear [Cu(N3)4]2− complex anions, while the utilisation of the (PeMIm)+ ion enables the isolation of a dinuclear [Cu2(N3)6]2− salt. By using the unsymmetrical imidazolium ions (BMIm)+ or (EMIm)+ salts with the trinuclear [Cu3(N3)8]2− complex anion are obtained. With the (DML)+ cation an azidocuprate(II) crystallizes, which contains both [Cu(N3)4]2− and the [Cu2(N3)6]2− anion. The anions in the salt with the (PeMIm)+ cation are interconnected through further Cu−N bonds and form layers with a 2D‐honeycomb structure. The trinuclear units in the (BMIm)+ and the (EMIm)+salts form coordination strands of different structures. [ABSTRACT FROM AUTHOR]

Azido-modified nucleosides have been extensively explored as substrates for click chemistry and the metabolic labeling of DNA and RNA. These compounds are also of interest as precursors for further synthetic elaboration and as therapeutic agents. This review discusses the chemistry of azidonucleosides related to the generation of nitrogen-centered radicals (NCRs) from the azido groups that are selectively inserted into the nucleoside frame along with the subsequent chemistry and biological implications of NCRs. For instance, the critical role of the sulfinylimine radical generated during inhibition of ribonucleotide reductases by 2′-azido-2′-deoxy pyrimidine nucleotides as well as the NCRs generated from azidonucleosides by radiation-produced (prehydrated and aqueous) electrons are discussed. Regio and stereoselectivity of incorporation of an azido group ("radical arm") into the frame of nucleoside and selective generation of NCRs under reductive conditions, which often produce the same radical species that are observed upon ionization events due to radiation and/or other oxidative conditions that are emphasized. NCRs generated from nucleoside-modified precursors other than azidonucleosides are also discussed but only with the direct relation to the same/similar NCRs derived from azidonucleosides. [ABSTRACT FROM AUTHOR]

Herein, we present a new application of fluorosulfonylazide (FSO2N3) for diazotizing a series of activated methylene compounds to deliver the corresponding diazo products. Notably, by the judicious choice of bases, the selective generation of the Bestmann‐Ohira reagent (BOR) or the Seyferth‐Gilbert reagent (SGR) has been realized from FSO2N3 and dimethyl‐2‐oxopropylphosphonate. We also investigated the kinetics of the homologation of aldehydes using these two reagents with K2CO3 as a base in MeOH, finding that a faster reaction rate was achieved by using SGR. Moreover, the facile one‐pot synthesis of terminal alkynes from aldehydes has been established, which could be further coupled with azides to deliver triazoles using CuAAC click chemistry. [ABSTRACT FROM AUTHOR]

Herein, we present a new application of fluorosulfonylazide (FSO2N3) for diazotizing a series of activated methylene compounds to deliver the corresponding diazo products. Notably, by the judicious choice of bases, the selective generation of the Bestmann‐Ohira reagent (BOR) or the Seyferth‐Gilbert reagent (SGR) has been realized from FSO2N3 and dimethyl‐2‐oxopropylphosphonate. We also investigated the kinetics of the homologation of aldehydes using these two reagents with K2CO3 as a base in MeOH, finding that a faster reaction rate was achieved by using SGR. Moreover, the facile one‐pot synthesis of terminal alkynes from aldehydes has been established, which could be further coupled with azides to deliver triazoles using CuAAC click chemistry. [ABSTRACT FROM AUTHOR]

Convenient access to 6‐alkylsulfonylmethyl phenanthridines has been demonstrated both under non‐catalytic thermal and visible‐light photoredox‐catalyzed conditions. A cascade of radical cyclization is triggered by the exposure of biphenyl vinyl azides to the in‐situ generated alkyl sulfonyl radicals from 4‐substituted Hanztsch esters in the presence of an SO2 surrogate. Transition metal‐free, mild reaction conditions, and broad substrate scope constitute some of the highlights of the approach. Also, the synthetic utility of the accessed 6‐alkylsulfonylmethyl phenanthridines has been demonstrated. [ABSTRACT FROM AUTHOR]

A selective intermolecular Schmidt reaction of equilibrating hydroxyalkyl allylic azides is reported to afford N-hydroxyalk-1-en-3-yl lactams in modest to high yields. For prochiral and chiral ketones, modest to high 1,5-diastereoselectivity was achieved, and the mechanistic analysis is supported by DFT calculation. [ABSTRACT FROM AUTHOR]

A series of terminal mono‐ and disubstituted beryllium azides of the form [(CAAC)Be(N3)R] (R=CAACH, Dur; CAACH/CAAC=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐yl/idene, Dur=2,3,5,6‐tetramethylphenyl) and [L2Be(N3)2] (L=CAACNH=1‐(2,6‐diisopropylphenyl)‐3,3,5,5‐tetramethylpyrrolidin‐2‐imine, IiPrMe=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene), respectively, were synthesized and characterized by NMR spectroscopy and X‐ray crystallography. Thermolysis and photolysis products of these first examples of tricoordinate azidoberyllium complexes evidence extensive ligand scrambling and the formal insertion of nitrenes into the CAAC−Be bond, generating cyclic alkyl(amino)imine (CAAI) ligands. Furthermore, the reaction with a small N‐heterocyclic carbene (NHC) leads to unexpected CAAC‐NHC ligand exchange, while the reaction with pentaphenylborole yields the first γ‐azide adduct of a borole, long postulated to be the first step in the synthesis of 1,2‐azaborinines from boroles and azides. [ABSTRACT FROM AUTHOR]

The research focused on the photolysis of ortho‐ and para‐substituted aryl azides and the preparation of 2‐arylamino‐substituted azepines. The best results were achieved in 1,4‐dioxane for ortho‐substituted azides and in ethanol for para‐substituted azides, respectively. It was found that reactions with arylamines, which have electron‐donating groups, typically produce higher yields of heterocycles than those with electron‐withdrawing groups. [ABSTRACT FROM AUTHOR]

A photoredox/copper co‐catalyzed ring‐opening cross‐coupling of aryl azides with cyclopropanols has been developed with fac‐Ir(ppy)3 as the photocatalyst. The reaction involves intermediacy of the anilino radical generated through reduction of the azido group by fac‐Ir(ppy)3* and [CuII]‐enabled oxidative ring‐opening of the cyclopropanol. An array of β‐aminoketone compounds were synthesized under redox‐neutral conditions by using this method. [ABSTRACT FROM AUTHOR]

This study proposes a new method for radionuclide therapy that involves the use of oligomeric 2,6-diisopropylphenyl azides and a chelator to form stable complexes with metallic radionuclides. The technique works by taking advantage of the endogenous acrolein produced by cancer cells. The azides react with the acrolein to give a diazo derivative that immediately attaches to the nearest organelle, effectively anchoring the radionuclide within the tumor. Preliminary in vivo experiments were conducted on a human lung carcinoma xenograft model, demonstrating the feasibility of this approach for cancer treatment. [ABSTRACT FROM AUTHOR]

Cu-catalyzed azide–alkyne cycloaddition (CuAAC) in the case of 1-iodoalkynes is known as a synthetic tool towards 5-iodo-1,2,3-triazole derivatives. We found that CuAAC of 1-iodobuta-1,3-diynes and aryl azides under CuI(PPh3)3 catalysis unexpectedly leads to the formation of both 4-iodo- and 5-iodo-1,2,3-triazoles. Aryl azides bearing acceptor groups and iodoaryldiacetylenes having donor groups shift the isomer ratio in favor of nontrivial 4-iodotriazoles. The reason for the change in the regioselectivity was explained using DFT calculations, which revealed the binuclear nature of the CuAAC transition states (TSs) for iodoalkynes and azides cycloaddition. The regiochemistry of cycloaddition is determined by the type of azide N atom coordinated to the Cu atom and by a spatial arrangement of the binuclear Cu catalyst and alkyne in the TS. In particular in the case of 1-iodobuta-1,3-diynes both regioisomeric TSs have a linear orientation of the alkyne moiety and the I–Cu–P fragment of the binuclear catalyst that makes both N1–Cu (for 5-I-TS) and N3–Cu (for 4-I-TS) coordination possible. The influence of various electronic and stereoelectronic effects established by NBO analysis, as well as NCI interactions, on the stabilization of isomeric TSs in the reactions of aryl/alkyl azides with iodomono- and diacetylenes is discussed. 4-Iodotriazoles are more thermodynamically stable than 5-iodotriazoles, while only the latter form I–N halogen bonds in the solid state. [ABSTRACT FROM AUTHOR]

An enhanced, sustainable, and efficient method for synthesizing tacrine, achieving a 98% yield, has been developed by replacing volatile organic compounds with more eco-friendly solvents such as deep eutectic solvent (DESs). The optimized protocol scales easily to 3 g of substrate without yield loss and extends successfully to tacrine derivatives with reduced hepatotoxicity. Particularly notable is the synthesis of novel triazole-based derivatives, yielding 90–95%, by integrating an in situ preparation of aryl azides in DESs with N-propargyl-substituted tacrine derivatives. Quantitative metrics validate the green aspects of the reported drug development processes. [ABSTRACT FROM AUTHOR]

Incorporation of a trifluoromethyl group with 1,2,3-triazoles motifs was described. We explored a click reaction approach for regioselective synthesis of 1-susbstituted-4-trifluoromethyl-1,2,3-triazoles in which 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) reacts with commercial 2-bromo-3,3,3-trifluoropropene (BTP) to form 3,3,3-trifloropropyne (TFP) in situ. Arising from merits associated with the availability and stability of BTP, and the high efficiencies of CuI/1,10-Phenanthroline (Phen)-catalyzed cycloaddition reactions of azides with alkynes, this readily performed click process takes place to form the target 1,2,3-triazoles in high yields, and with a wide azide substrate scope. The potential value of this protocol was demonstrated by its application to a gram-scale reaction. [ABSTRACT FROM AUTHOR]

This article explores a new method for synthesizing carbamoyl azides, which are important for creating amines. The authors propose using NHP esters and TMSN3 to form C-N bonds through a nucleophilic substitution process. They optimized the reaction conditions and demonstrated the method's effectiveness with various NHP esters. Control experiments were conducted to understand the mechanism, which involves the coordination of NHP esters with ferric acetate, nucleophilic attack, and Curtius rearrangement. This method offers a convenient and efficient approach for synthesizing carbamoyl azides. The authors of the article are Xiaobin Yuan, Yanjie Qu, Yajun Li, and Hongli Bao. [Extracted from the article]

A vicinal diamine motif can be found in numerous natural compounds and pharmaceuticals, making it an important synthetic target. Herein, we report a telescoped synthesis of vicinal diamines under continuous flow conditions. This approach involves the electrochemical aziridination of alkenes with primary amines, followed by the strain-release driven ring-opening using various nitrogen nucleophiles. The efficacy of the developed method was demonstrated through the synthesis of diverse symmetrically and non-symmetrically substituted vicinal diamines, as well as vicinal amino azides, which can be further hydrogenated to diamines in flow. Additionally, O-centered nucleophiles were employed for the ring-opening of aziridines in our telescoped synthesis, yielding vicinal amino ethers and alcohol. This process offers a streamlined and efficient pathway for the direct synthesis of valuable products from readily available starting materials, bypassing the isolation of unstable aziridine intermediates. [ABSTRACT FROM AUTHOR]