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We describe here the palladium hydrogenation of ethyl 5-(benzoyloxymethyl)isoxazole-3-carboxylate. The presence of two reducible sites in the molecule, namely the benzylic-like position and the isoxazole N–O bond, creates a possible competition. The results show that under the applied conditions, ethyl (Z)-2-amino-4-oxo-2-pentanoate is obtained as the only product. Accordingly, a domino process occurs, consisting of deoxygenation to the 5-methylisoxazole derivative followed by reductive opening of the isoxazole ring. The isoxazole substrate was prepared by NaOH-catalyzed cycloaddition-condensation of ethyl nitroacetate and propargyl benzoate in water. Complete characterizations of the isoxazole and Z-enaminone derivatives are reported. [ABSTRACT FROM AUTHOR]

Dynamic covalent polymers have gained more and more attention for their fascinating dynamic features and broad application prospects. As an emerging and powerful synthetic tool, X‐yne click polymerization, mainly including thiol‐yne, amino‐yne and hydroxyl‐yne click polymerizations, has been rapidly developed and widely applied in the preparation of functional polymers in recent years. Moreover, dynamic exchange processes have been successively observed in different X‐yne adducts, and then several dynamic covalent polymers have been obtained by X‐yne click polymerization. The combination of these two aspects not only provides a highly efficient synthetic approach for dynamic covalent polymers, but also further expands the application scope of X‐yne click polymerization, achieving a win–win situation. In this review, we sort out the dynamic exchange mechanisms based on the formation of β‐heteroatom enolate intermediates and give a detailed account of the progress of dynamic covalent polymers generated from X‐yne click polymerization and their applications in covalent adaptable networks (CANs), self‐healing injectable polymer hydrogels and functional porous polymeric films, etc. The existing deficiencies and future prospects in this field are also discussed. [ABSTRACT FROM AUTHOR]

BackgroundTreatment and prophylaxis options for neonatal HIV are limited. This study aimed to develop a population pharmacokinetic model to characterize the disposition of maraviroc in neonates to inform dosing regimens and expand available options.MethodsUsing maraviroc concentrations from neonates who received either a single dose or multiple doses of 8 mg/kg of maraviroc in the first 6 weeks of life, a population pharmacokinetic model was developed to determine the effects of age, sex, maternal efavirenz exposure and concomitant ARV therapy on maraviroc disposition. The final model was used in Monte Carlo simulations to generate expected exposures with recommended dosing regimens.ResultsA total of 396 maraviroc concentrations, collected in the first 4 days of life, at 1 week, at 4 weeks and at 6 weeks, from 44 neonates were included in the analysis. After allometrically scaling for weight, age less than 4 days was associated with a 44% decreased apparent clearance compared with participants 7 days to 6 weeks of life. There were no differences identified in apparent clearance or volume of distribution from ages 7 days to 6 weeks, sex, maternal efavirenz exposure or concomitant nevirapine therapy. Monte Carlo simulations with FDA-approved weight band dosing resulted in the majority of simulated patients (84.3%) achieving an average concentration of ≥75 ng/mL.ConclusionsWhile maraviroc apparent clearance is decreased in the first few days of life, the current FDA-approved maraviroc weight band dosing provides maraviroc exposures for neonates in the first 6 weeks of life, which were consistent with adult maraviroc exposure range. Maraviroc provides another antiretroviral treatment option for very young infants.

BackgroundA 4-month regimen containing rifapentine and moxifloxacin has noninferior efficacy compared to the standard 6-month regimen for drug-sensitive tuberculosis. We evaluated the effect of regimens containing daily, high-dose rifapentine on efavirenz pharmacokinetics and viral suppression in patients with human immunodeficiency virus (HIV)-associated tuberculosis (TB).MethodsIn the context of a Phase 3 randomized controlled trial, HIV-positive individuals already virally suppressed on efavirenz--containing antiretroviral therapy (ART) (EFV1), or newly initiating efavirenz (EFV2) received TB treatment containing rifapentine (1200 mg), isoniazid, pyrazinamide, and either ethambutol or moxifloxacin. Mid-interval efavirenz concentrations were measured (a) during ART and TB cotreatment (Weeks 4, 8, 12, and 17, different by EFV group) and (b) when ART was taken alone (pre- or post-TB treatment, Weeks 0 and 22). Apparent oral clearance (CL/F) was estimated and compared. Target mid-interval efavirenz concentrations were > 1 mg/L. Co-treatment was considered acceptable if > 80% of participants had mid-interval efavirenz concentrations meeting this target.ResultsEFV1 and EFV2 included 70 and 41 evaluable participants, respectively. The geometric mean ratio comparing efavirenz CL/F with vs without TB drugs was 0.79 (90% confidence interval [CI] .72-.85) in EFV1 and 0.84 [90% CI .69-.97] in EFV2. The percent of participants with mid-interval efavirenz concentrations > 1mg/L in EFV1 at Weeks 0, 4, 8, and 17 was 96%, 96%, 88%, and 89%, respectively. In EFV2, at approximately 4 and 8 weeks post efavirenz initiation, the value was 98%.ConclusionsTB treatment containing high-dose daily rifapentine modestly decreased (rather than increased) efavirenz clearance and therapeutic targets were met supporting the use of efavirenz with these regimens, without dose adjustment.Clinical trials registrationNCT02410772.

IntroductionContraceptive implants containing etonogestrel and levonorgestrel have emerged as popular contraceptive options among women in areas of high HIV burden in sub-Saharan Africa. However, recent pharmacokinetic data have shown drug-drug interactions between implants and efavirenz-containing antiretroviral therapy (ART), reducing the effectiveness of the implants. Here, we evaluated pregnancy incidence in 6-month intervals following implant initiation among women using efavirenz and contraceptive implants to assess whether the risk of breakthrough pregnancy is higher after specific periods of implant use.MethodsWe used data from a retrospective longitudinal analysis of women living with HIV ages 18-45 years in western Kenya who attended HIV-care facilities between 2011 and 2015. We used Cox proportional hazard models to compute hazard ratios (HRs) for breakthrough pregnancy by implant type and ART regimen. Depending on the model, we adjusted for socio-demographic and clinical factors, programme, site and interaction between calendar time and ART regimen. We utilized inverse probability weights (IPWs) to account for three sampling phases (electronic medical record [EMR], chart review and phone interview) and calculated overall parameter estimates.ResultsWomen contributed 14,768 woman-years from the largest sampling phase (EMR). The median age was 31 years. Women used etonogestrel implants for 26-69% of the time and levonorgestrel implants for 7-31% of the time, depending on the sampling phase. Women used efavirenz, nevirapine or no ART for 27-33%, 40-46% and 15-26% of follow-ups, respectively. When combining sampling phases, there was little evidence to suggest that the relative hazard of pregnancy among efavirenz-containing ART users relative to nevirapine-containing ART changed with length of time on implants: IPW-adjusted HR of 3.1 (CI: [1.5; 6.4]) at 12 months, 3.4 (CI: [1.8; 6.3]) at 24 months, 3.8 (CI: [1.9; 7.7]) at 36 months and 4.2 (CI: [1.6; 11.1]) at 48 months (interaction p-value = 0.88). Similarly, no significant change in HRs over time was found when comparing women not using ART to nevirapine-containing ART users (interaction p-value = 0.49).ConclusionsWe did not find evidence to suggest implants being more fallible from drug-drug interactions with efavirenz at later time intervals of implant use. Thus, we would not recommend shortening the duration of implant use or replacing implants sooner when concomitantly used with efavirenz.

Large donor–acceptor scaffolds derived from polycyclic aromatic hydrocarbons (PAHs) with tunable HOMO and LUMO energies are important for several applications, such as organic photovoltaics. Here, we present a large selection of PAHs based on central indenofluorene (IF) or fluorene cores and containing various dithiafulvene (DTF) donor units that gain aromaticity upon oxidation and a variety of acceptor units, such as vinylic diesters, enediynes, and cross-conjugated radiaannulenes (RAs) that gain aromaticity upon reduction. In some cases, the DTF units are expanded by pyrrolo annelation. The optical and redox properties of these compounds, in some cases carbon-rich, were studied by UV–vis absorption spectroscopy and cyclic voltammetry. Synthetically, the work explores IF diones or fluorenone as central building blocks by subjecting the carbonyl groups to a variety of reactions; that are, phosphite- or Lawesson’s reagent-mediated olefination reactions (to introduce DTF motifs), Ramirez/Corey–Fuchs dibromo-olefinations followed by Sonogashira couplings (to introduce enediynes motifs), and Knoevenagel condensations (to introduce the vinylic diester motif). By a subsequent Glaser–Hay coupling reaction, a RA acceptor unit was introduced to provide a DTF-IF-RA donor–acceptor scaffold with a low-energy charge-transfer absorption and multi-redox behavior.

In this paper, we report the synthesis of alkyl-tethered alkynes through ozone-mediated and FeII-catalyzed dealkenylative alkynylation of unactivated alkenes in the presence of alkynyl sulfones. This one-pot reaction, which employs a combination of a catalytic FeII salt and l-ascorbic acid, proceeds under mild conditions with good efficiency, high stereoselectivity, and broad functional group compatibility. In contrast to our previous FeII-mediated reductive fragmentation of α-methoxyhydroperoxides, the FeII-catalyzed process was devised through a thorough kinetic analysis of the multiple competing radical (redox) pathways. We highlight the potential of this dealkenylative alkynylation through multiple post-synthetic transformations and late-stage diversifications of complex molecules, including natural products and pharmaceuticals.

Natural products are a diverse class of biologically produced compounds that participate in fundamental biological processes such as cell signaling, nutrient acquisition, and interference competition. Unique triple-bond functionalities like isonitriles and alkynes often drive bioactivity and may serve as indicators of novel chemical logic and enzymatic machinery. Yet, the biosynthetic underpinnings of these groups remain only partially understood, constraining the opportunity to rationally engineer biomolecules with these functionalities for applications in pharmaceuticals, bioorthogonal chemistry, and other value-added chemical processes. Here, we focus our review on characterized biosynthetic pathways for isonitrile and alkyne functionalities, their bioorthogonal transformations, and prospects for engineering their biosynthetic machinery for biotechnological applications.

The high cost of viral load (VL) testing limits its use for antiretroviral therapy (ART) adherence support. A low-cost lateral flow urine tenofovir (TFV) rapid assay predicts pre-exposure prophylaxis breakthroughs, but has not yet been investigated in HIV treatment. We therefore evaluated its utility in a pilot cross-sectional study of TFV-containing ART recipients at an increased risk of virologic failure (VF). Participants who had a treatment interruption ≥30 days or had ≥1 episode of viremia (VL ≥400 copies/mL) in the previous year were recruited from a public health setting in Cape Town, South Africa. Self-reported adherence data were collected, the urine TFV assay performed, and concurrent TFV-diphosphate analyzed in dried blood spots. VL testing was done concurrently and, if viremic, genotypic HIV drug resistance testing was performed. Of 48 participants, 18 (37.5%) had VL (>400 copies/mL) at the time of the study, including 16 of 39 receiving efavirenz (EFV), 2 of 6 receiving protease inhibitors, and 0 of 3 receiving dolutegravir. Resistance testing succeeded in 17/18, of which 14 had significant mutations compromising ≥2 agents of the current EFV-based regimen. Of these 14, all had detected urine TFV. Urine TFV was undetectable in two out of three without regimen-relevant resistance; p = .02. In participants on EFV-based regimens returning to care, VF was largely due to viral resistance, where detectable urine TFV had 100% sensitivity (14/14 participants) in predicting resistance. Conversely, when undetectable, the urine-based assay could be used to preclude participants with poor adherence from undergoing costly HIV drug resistance testing.

Treatment of the rhodium pincer complexes [RhCl(RPm)] (RPm = N,N′-bis(di-R-phosphinomethyl)perimidinylidene, R = Ph, Cy) with triphenylcyclopropenium hexafluorophosphate affords rhodacyclobutadiene complexes. These in turn react with activated alkynes (RC≡CCO2Me, R = H, CO2Me) to afford unusually stable cyclopropenylvinyls, implicating the intermediacy of σ-cyclopropenyl isomers. In contrast, treatment of [RhCl{py(NHPtBu2)2-2,6}] with the same reagent instead results in double functionalisation (SEAr) at the pincer backbone. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a bis-iron(II) complex was accomplished upon treatment of a phosphine free NNN-pincer ligand (L) with FeCl2·4H2O under ambient conditions. The deep greenish colored iron(II) complex (Fe-1) was characterized by a single-crystal X-ray diffraction study along with IR spectroscopy, UV-Vis spectroscopy, mass spectrometry, and elemental analysis. The Fe-1 complex was tested for the transfer semi-hydrogenation of terminal alkynes to the corresponding alkenes through the dehydrogenation of dimethyl amine-borane. This procedure enables the conversion of various structurally different terminal alkynes to alkenes under mild conditions. Control experiments were performed to shed light on the possible intermediates generated during the present protocol. [ABSTRACT FROM AUTHOR]

Starting from readily available enantiopure azidomethyl‐substituted bicyclic 1,2‐oxazine derivatives and mono‐, di‐ or trialkynes, their copper‐catalyzed (3+2) cycloadditions furnished a series of 1,2,3‐triazolyl‐linked compounds in good yields. These click reactions proceeded smoothly at room temperature when copper iodide as catalyst was used in the presence of triethylamine and tris[(1‐gbenzyl‐1H‐1,2,3‐triazol‐4‐yl)methyl]amine as ligand. Generally, the unprotected bicyclic 1,2‐oxazine derivatives seemed to show slightly higher reactivity and provided better yields compared with their silyl‐protected counterparts. Exhaustive hydrogenolysis with cleavage of the 1,2‐oxazine N−O bonds in the presence of palladium on charcoal as promotor is feasible but was found to be capricious. Reasonable results were obtained when acetic acid was employed as cosolvent. By applying these conditions, several of the bicyclic 1,2‐oxazine derivatives were successfully converted into the expected mono‐ or divalent aminooxepine derivatives which can be regarded as aminoseptanose mimetics. [ABSTRACT FROM AUTHOR]

The combination of a sulfonimidoyl and aminosulfoxonium group with a double bond renders vinyl sulfoximines and vinyl aminosulfoxonium salts particularly versatile classes of compounds in organic synthesis. The discussion of vinyl sulfoximines includes in addition to the synthesis, the Michael reaction and its application in asymmetric synthesis, the synthesis, structure and application of α‐lithiovinyl sulfoximines, the nickel‐catalyzed and copper‐mediated anionic cross‐coupling reaction of α‐metallovinyl sulfoximines, the synthesis of acyclic and cyclic dienyl vinyl sulfoximines and the ring‐closing metathesis, the hydroalumination and reductive Pauson‐Khand reaction, the nickel‐catalyzed cross‐coupling reaction, the vinyl‐allyl isomerization, the cycloaddition, and the cyclization. The discussion of vinyl aminosulfoxonium salts includes in addition to the synthesis, the Michael reaction, the ethylenation of protic nucleophiles, the synthesis of allyl aminosulfoxonium salts and the nucleophilic substitution, the synthesis of allyl aminosulfoxonium ylides and the imino ester aziridination, the synthesis of vinyl aminosulfoxonium ylides, the synthesis of alkynes and dihydrofurans, the nickel‐catalyzed cross‐coupling reaction, and the intramolecular substitution of the amino group. [ABSTRACT FROM AUTHOR]

Two Ru(II)‐catalytic systems were developed for anti‐Markovnikov regioselective hydroacyloxylations of terminal alkynes to vinylic esters. [Ru(NCCH3)6][(BF4)2] favors (E)‐vinylic ester products with arylacetylenes and select carboxylic acids, whereas a Ru scorpionate complex with two electron‐withdrawing ligands favors (Z)‐vinylic ester isomers. [ABSTRACT FROM AUTHOR]

We report the Ni‐catalyzed cycloisomerization of 1,5‐allenynes. Substrates containing terminal alkynes afford cyclopentene derivatives, whereas internal alkynes lead to the formation of two consecutive C−C bonds to give fused 5–5 bicyclic compounds. The reaction shows a wide scope. Experimental and computational mechanistic studies suggest a Ni(0)−Ni(II) catalytic cycle. The reaction starts with an oxidative cyclometallation followed by a β‐hydrogen elimination. The trans arrangement of alkenyl and hydride ligands is key to allow formation of the second carbocycle. [ABSTRACT FROM AUTHOR]

A direct thiocyanatosulfonation of alkynes with sulfinic acids and potassium thiocyanate was developed at room temperature. This method provided a efficient and practical pathway to selectively access (E)‐β‐(thiocyanato)vinyl sulfones by two C−S bonds formation in one step under metal‐free condition. The advantages of this method included simple reaction conditions, easily available starting materials, good functional group compatibility, high regio‐ and stereoselectivity and good to excellent yields of products. [ABSTRACT FROM AUTHOR]

A one‐pot, three‐component, base‐mediated [3+2] cycloaddition reaction to synthesize 1H‐pyrrol‐3(2H)‐ones from readily available amino acid esters, aldehydes, and terminal alkynes was reported. Isolation of the intermediate and the detailed mechanistic study revealed the course of the reaction. This multi‐component reaction proceeds via imine formation followed by the nucleophilic addition of alkyne to form a propargylamine precursor. Base‐mediated conversion of propargylamine precursor into 1‐azadiene followed by in situ ketene formation leading to [3+2] cycloaddition that ultimately produces unusual 1H‐pyrrol‐3(2H)‐ones. [ABSTRACT FROM AUTHOR]

We herein report the regio- and chemoselective hydroboration of terminal alkynes with pinacolborane by a series of constrained-geometry catalyst-type or CGC-type rare earth metal monoalkyl complexes. This protocol offers a 100% atom-efficient and straightforward route for the synthesis of a variety of (E)-1-alkenylborons with the advantages such as high yield, high E-selectivity up to >99.9%, multiple metal center, broad substrate scope, broad functional-group tolerance, and no necessity for a solvent. A gram-scale synthesis and subsequent transformations of (E)-1-alkenylboron to several functional compounds suggest the practical applications of this synthetic methodology. The reaction mechanism has been explored through ESI-MS, isotopic labeling experiments, and in situ1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Dearomative intramolecular Diels–Alder/sulfur extrusion reaction of thiophenes with alkynes successfully afforded fluoranthenes in moderate to excellent yields. The proximity of both reactive sites fixed at the peri‐position of naphthalene would play an important role in the progress of this reaction. Tri(o‐tolyl)phosphine effectively suppressed the side reactions as a sulfur scavenger. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of unsaturated hydrocarbons to alkenes and alkanes using molecular hydrogen is one of the most fundamental transformations in organic synthesis. While methodologies involving transition metals as catalysts in homogeneous and heterogeneous processes have been well developed, metal‐free catalytic hydrogenation offers an ideal approach for future chemistry. Herein, the common and inexpensive quaternary ammonium salts are first introduced as catalysts in the catalytic hydrogenation system for the transformations from alkynes or olefins into the corresponding olefins or alkanes. Interestingly, the hydrogenation process of alkynes can be controlled to selectively produce alkenes or alkanes under different conditions. Moreover, the possible mechanism is discussed in new insights into the catalytic behavior of quaternary ammonium salts. [ABSTRACT FROM AUTHOR]

Alkenylboronates are highly versatile building blocks and valuable reagents in the synthesis of complex molecules. Compared with that of monosubstituted alkenylboronates, the synthesis of multisubstituted alkenylboronates is challenging. The copper‐catalyzed carboboration of alkynes is an operationally simple and straightforward method for synthesizing bis/trisubstituted alkenylboronates. In this work, a series of copper‐metallized N‐Heterocyclic Carbene (NHC) ligand porous polymer catalysts are designed and synthesized in accordance with the mechanism of carboboration. By using CuCl@POL‐NHC‐Ph as the optimal nanocatalyst, this study realizes the β‐regio‐ and stereoselective (syn‐addition) 1,2‐carboboration of alkynes (regioselectivity up to >99:1) with satisfactory yields and a wide range of substrates. This work not only overcomes the selectivity of carboboration but also provides a new strategy for the design of nanocatalysts and their application in organic synthesis. [ABSTRACT FROM AUTHOR]

1,2,4-Triazoline-3,5-diones (TADs) are versatile reagents and have found widespread adoption in chemical science. Despite their remarkable reactivity toward a wide array of unsaturated hydrocarbons, the chemical reaction between TADs and alkynes has remained largely unexplored. Herein, we demonstrate that 1,1,1,3,3,3-hexafluoro-2-propanol facilitates the unusual [3+2] cycloaddition between 4-phenyl-1,2,4-triazoline-3,5-dione and alkynes, resulting in the formation of unprecedented mesoionic triazolones. Moreover, the structural properties of the resulting triazolone have been investigated by employing X-ray diffraction analysis and Density Functional Theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Herein, we disclose a visible‐light‐induced rhodium‐catalyzed oxidative C−H/N−H bond activation of sulfonimidamides (SIAs) and subsequent [4+2] annulation with an alkyne in water to yield SIA‐based 1,2‐benzothiazines in good to high yields in short reaction times. Further, the C=C bond of the benzothiazine can be cleaved under environmentally friendly conditions (oxygen atmosphere and blue LEDs) to deliver o‐acyl‐N‐acyl SIAs. Interestingly, o‐acyl‐N‐acyl SIAs can also be synthesized directly from SIAs in very good yields without isolating the benzothiazine. The selective and efficient reduction of the benzothiazine C=C bond in the presence of InCl3/R3SiH led to the formation of a hitherto unknown SIA‐based dihydro‐1,2‐benzothiazine in quantitative yield. [ABSTRACT FROM AUTHOR]

A novel strategy of visible‐light photoredox catalysis ipso‐annulation of activated alkynes with polychloroalkanes for the synthesis of 3‐polychloroalkyl spiro[4,5]trienones, which used 4‐methoxybenzenediazonium tetrafluoroborate salt as a hydrogen atom transfer reagent, is described. This polychloroalkylation/ spirocyclization of alkynes offers a widely range of 3‐polychloroalkyl‐spiro[4,5]trienone derivatives in high yields with a broad substrate scope via selective C(sp3)‐H homolytic cleavage. The results of controlled experiments showed that this method involves a radical process. The polyhaloalkyl radical species generated from intermolecular hydrogen atom transfer (HAT) between aryl radical and polychloroalkanes. [ABSTRACT FROM AUTHOR]

Considering the potential importance and upsurge in demand, the selective semi-hydrogenation of alkynes to (E)-olefins has attracted significant interest. This article highlights the recent advances in newer technologies and important methodologies directed to (E)-olefins from alkynes developed from 2015 to 2023. Notable features summarised include the catalyst or ligand design and control of product selectivity based on precious and nonprecious metal catalysts for semi-hydrogenation to (E)-olefins. Mechanistic studies for various catalytic transformations, including synthetic application to bioactive compounds, are summarised. [ABSTRACT FROM AUTHOR]

An environmentally benign, transition metal- and base-free, iodine-promoted atom-economical protocol for the synthesis of the privileged isoquinolone scaffold via regioselective intramolecular iodoamidation of alkynes under mild conditions has been developed. The present synthetic approach being metal, additive, and solvent-free adheres to the principles of green chemistry, as it tends to minimize waste production. The synthesized product contains an iodo as well as a free –OH group that is readily accessible for subsequent transformation to afford biologically relevant compounds. [ABSTRACT FROM AUTHOR]

We have developed a visible-light mediated copper(I) chloride catalyzed regioselective oxidative diamination reaction of 2-aminopyridines with terminal alkynes to form substituted imidazo[1,2-α]pyridine products at room temperature using molecular oxygen as a green oxidant. This is the first photochemical report on the synthesis of 3-alkyl/aryl-2-(aryl/alkylethynyl)imidazo[1,2-α]pyridines and involves the formation of two C–N and one C–C bond at RT. Compared to a literature reported 3-step thermal method, the current photochemical process requires a single step to synthesize the substituted imidazo[1,2-α]pyridine product. Moreover, the green chemistry metrics (E-factor is 5.5) and Eco-Scale (value is 53.65) evaluations reveal that this process is an acceptable green organic synthesis process. Thus, this photochemical oxidative diamination reaction is simple, green, environmentally-friendly, cost-effective, and energy-efficient. [ABSTRACT FROM AUTHOR]

Alkenes and alkynes are among the most fundamental and valuable synthons utilized to create atom- and step-efficient heterocyclic compounds, which are crucial components of many drugs, natural products, and essential intermediates in contemporary synthetic organic chemistry. Furthermore, because of their many physical, chemical, and biological properties, nitrogen-based motifs have become crucial building blocks in materials and pharmaceutical chemistry. Consequently, nitrogen heterocycles have been decorated with numerous chromophores and fine chemicals via novel synthetic techniques and procedures to enhance their functional properties. Traditional reactions require predetermined reagents and appropriate interacting catalysts. Alternatively, photoinduced techniques do not require these conditions as light may directly interact with molecules and increase their reactivity. Since nitrogen scaffolds are present in >50% of all medicinal and functional materials, creating an effective synthetic process employing a photo-induced approach has become a valuable tool in recent years. This study summarizes and presents photocatalytic processes for the synthesis of nitrogen-enriched heterocycles from saturated and unsaturated alkynes and alkenes. Alternative methods involving the activation of nitrogen precursors are also discussed and compared. [ABSTRACT FROM AUTHOR]

A new strategy has been developed for the synthesis of internal alkynes in aqueous media via the coupling of aryl iodides with terminal alkynes, catalyzed by a PdCl2–polar arylphosphine ligand system. The developed procedure was used to synthesize of acetylenic benzamides in mild conditions and high yields of 85–93%. [ABSTRACT FROM AUTHOR]

Several platinum (II) complexes bearing heteroatom‐substituted phosphine oxides ligand H(O)P(OCMe2CMe2O) were obtained. The H‐phosphonate was synthesized in an alternative, one‐pot procedure with the use of water from hexamethylphosphorus triamide and pinacol. In the presence of H(O)P (OCMe2CMe2O) ligand, [PtCl2(cod)] was converted into three new complexes: [PtCl2{P(OH)(OCMe2CMe2O)}2] [Pt1], [PtCl{P(O)(OCMe2CMe2O)}{P(OH)(OCMe2CMe2O)}2] [Pt2], and [Pt{P(OH)(OCMe2CMe2O)}4]Cl2 [Pt3]. When [PtCl2(PPh3)2] was utilized as the substrate, [PtCl(PPh3)2{P(OH)(OCMe2CMe2O)}]Cl [Pt4] and [PtCl(PPh3)2{P(O)(OCMe2CMe2O)}] [Pt5] complexes were obtained, as the results of reaction with H(O)P(OCMe2CMe2O) and HP(OCMe2CMe2O)(OCH2CMe2NH) ligands. The structural features of all complexes were characterized by physicochemical and spectroscopic methods as well as single X‐ray diffraction studies. Complex [Pt1] was found to promote cascade reaction, the addition of water to triple bond, and hydrogen/deuterium exchange reaction. The hydration reaction of substituted terminal aryl alkynes gave exclusively Markovnikov products and tolerated different functional groups. Various aryl ketones were synthesized in good to excellent yield. H/D exchange reaction was exemplified by the model reaction of acetophenone in deuterium containing methanol. Factors influencing the effectiveness of the hydrogen/deuterium exchange reaction of the methyl group were determined. The cascade procedure bears the potential to overcome the limitations of conventional synthesis and unlocks practical use in the synthesis of deuterium‐labeled pharmaceuticals. [ABSTRACT FROM AUTHOR]

2-(arylethynyl)selanyl-azoles are important and vital compounds that both azoles and aryl ethynyl selenides presented in their structure. In this article, we have constructed copper (I) iodide supported on the surface of magnetic Fe3O4 nanoparticles functionalized with Serine [Fe3O4-Serine-CuI] and evaluated its catalytic behavior in the preparation of 2-(arylethynyl)selanyl-azoles though one-pot three-component coupling reaction of azoles, Se powder and alkynes under ecofriendly conditions. The structure of Fe3O4-Serine-CuI nanocatalyst is well analyzed by several spectroscopic techniques like: FT-IR, SEM, EDX, TEM, MAP, XRD, TGA, VSM, ICP-OES techniques. High reusability and well characterization of Fe3O4-Serine-CuI nanocatalyst, high purity and yields of products, ecofriendly conditions, and simple operation are several considerable advantages this catalytic system. [ABSTRACT FROM AUTHOR]

The reaction of ferrocene-containing alkenes and alkynes with HSi(OEt)3 and HSiMe(OMe)2 in the presence of Karstedt catalyst (Pt2[(Me2SiCH=CH2)2O]3) was studied. It was found that only terminal alkenes underwent hydrosilylation, while alkynes entered this reaction even in the case of a disubstituted C≡C bond. The synthesized silicon-containing ferrocene derivatives were used as precursors for the preparation of siloxane aerogels, which were characterized by low-temperature nitrogen adsorption, scanning electron microscopy, and Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

This review summarizes the studies on the palladium carboxylate π-complexes with unsaturated hydrocarbons (alkenes, alkynes, and arenes) as well as with N-heterocyclic carbenes, phosphonyl-substituted ferrocene ligands, etc. In these complexes the palladium atoms are coordinated with unsaturated hydrocarbons via the carbon atoms forming the multiple bonds. These complexes are traditional objects in fundamental coordination chemistry including chemistry of polynuclear compounds. They are also applied as pre-catalysts and as model intermediates for catalytic transformations of unsaturated hydrocarbons, e.g., oxidation and isomerization of alkenes, hydrogenation and coupling reactions of alkenes, alkynes, and arenes. [ABSTRACT FROM AUTHOR]

An efficient, highly selective and divergent synthetic method to construct 2‐substituted indoles and aryl‐annulated carbazoles via the intermolecular generation of α‐imino gold carbenes from terminal alkynes or diynes in combination with sulfilimines is disclosed. Importantly, the tandem reaction is proposed to proceed through an intermolecular gold carbene generation/C−H annulation followed by the activation of a second alkyne leading to 6‐endo‐dig cyclization, which is significantly different from previous dual activation or 1,6‐carbene shift approaches for diyne systems. In the case of ortho‐alkynylaniline as starting material, an unexpected regioselective formation of the indole moiety via the intermolecular path, instead of intramolecular hydroamination was discovered. This reactivity paved the way for a one‐pot synthesis of the 11H‐indolo [3,2‐c] quinoline scaffold by exploiting the formed amino indole for a subsequent Pictet–Spengler reaction with aldehydes. The photophysical properties of the carbazoles indicated good violet‐blue emission with quantum yields up to 40 %. [ABSTRACT FROM AUTHOR]

In this paper, we report BF3 ⋅ OEt2 as a catalyst to shuttle equivalents of HF from a fluoroalkane to an alkyne. Reactions of terminal and internal aliphatic alkynes led to formation of difluoroalkane products, while diarylalkynes can be selectively converted into fluoroalkenes. The method tolerates numerous sensitive functional groups including halogen, protected amine, ester and thiophene substituents. Mechanistic studies (DFT, probe experiments) suggest the catalyst is involved in both the defluorination and fluorination steps, with BF3 acting as a Lewis acid and OEt2 a weak Lewis base that mediates proton transfer. In certain cases, the interconversion of fluoroalkene and difluoroalkane products was found to be reversible. The new catalytic system was applied to demonstrate proof‐of‐concept recycling of poly(vinylidene difluoride). [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of ynamides, a class of N-alkynyl compounds, through various catalytic reactions. The authors highlight the importance of ynamides in the synthesis of nitrogen-containing scaffolds and summarize existing methods for their synthesis. They also present their own research on the direct catalytic addition of terminal alkynes to azodicarboxylates to produce ynehydrazides, which can then be converted into ynamides. The authors propose potential future directions for further research in this field. [Extracted from the article]

This article explores the borylative difunctionalization of unsaturated hydrocarbons using borylcopper species. It discusses the importance of developing simple and effective methods for preparing organoboron compounds. The article focuses on Cu-catalyzed reactions, including regioselective hydroborations, boroallylation, boroacylation, and boroformylation of 1,2-dienes. The authors describe the development of catalyst systems and ligands that have shown high yields and selectivities in these reactions. The research aims to contribute to the field of organic synthesis by developing efficient and selective catalytic reactions for the functionalization of unsaturated hydrocarbons. [Extracted from the article]

Herein we introduce 3-vinyl-1,2,4-triazines derivatives as dual-reactive linkers that exhibit selectivity towards cysteine and specific strained alkynes, enabling conjugate addition and inverse electron-demand Diels–Alder (IEDDA) reactions. This approach facilitates site-selective bioconjugation of biologically relevant peptides, followed by rapid and highly selective reactions with bicyclononyne (BCN) reagents. [ABSTRACT FROM AUTHOR]

The oxidative radical cascade cyclization of alkynes has emerged as a versatile strategy for the efficient construction of diverse structural units and complex molecules in organic chemistry. This work reports an alkyl radical initiated 5-exo-trig cyclization of biaryl ynones with 1,4-dihydropyridines to selectively synthesize indenones. [ABSTRACT FROM AUTHOR]

A cobalt‐catalyzed annulation of o‐phenylenediamines and internal alkynes for the synthesis of quinoxalines is developed. This method provides a variety of quinoxalines in good to high yields under a simple and mild reaction conditions with molecular O2 as a terminal oxidant. Preliminary mechanistic studies show that a novel reaction mechanism is involved in the current reaction, which is different from the previous reported dicarbonyl compound mechanism via the oxidation of the alkyne. [ABSTRACT FROM AUTHOR]

We, herein, report a Pd(0) and Brønsted acid-catalyzed redox-neutral intramolecular N-allylation of indoles and pyrroles with alkynes for the synthesis of biologically important imidazolidinone-fused N-heterocycles. The allylation is completely atom-economical and is applicable to a wide range of substrates. The methodology eliminates the use of a leaving group or an oxidizing agent, often employed for the allylation of nucleophiles. To the best of our knowledge, N-allylation of indoles and pyrroles with alkynes has not been reported to date. [ABSTRACT FROM AUTHOR]

Herein, a novel cascade gold(I)-catalyzed hydroarylation of alkynylindoles and subsequent Diels–Alder cycloaddition with electron-deficient alkynes and alkenes is described. A variety of azepino-fused hydrocarbazoles and carbazoles were obtained in moderate to excellent yields. Key features of this methodology are low catalyst loadings, high regioselectivity, broad functional group tolerances, access to important heterocycles, and 100% atom economy. [ABSTRACT FROM AUTHOR]

Sp3‐hybridized carbons‐rich molecules play a crucial role in drug discovery. Cobalt‐catalyzed hydroalkylation of alkenes and alkynes is an efficient method to synthesize these compounds. These reactions exhibit a wide range of applicability and high tolerance for functional groups, utilizing readily available alkenes and alkynes instead of hyperactive metallic reagents. Herein, we summarize the advancements of cobalt‐catalyzed hydroalkylation of alkenes and alkynes, according to different reaction mechanisms. We present a detailed discussion of the scope and limitations, plausible mechanisms and the opportunities for further development. [ABSTRACT FROM AUTHOR]

The reactivity of sydnones and sydnonimines toward terminal alkynes under copper catalysis has been explored using High‐Throughput‐Experimentation. A large panel of ligands and reaction conditions have been tested to optimize the copper‐catalyzed sydnone click reaction discovered by our group ten years ago. This screening approach led to the identification of new ligands, which boosted the catalytic properties of copper and allowed the discovery of a new copper‐catalyzed click‐and‐release reaction involving sydnonimines. This reaction allowed chemoselective ligation of terminal alkynes with sydnonimines and, simultaneously, the release of an isocyanate fragment molecule that can be used for further transformations. [ABSTRACT FROM AUTHOR]

A SeO2‐mediated regioselective synthesis of multi‐substituted furans has been achieved through intermolecular cyclization of terminal alkynes with aldehydes. The developed methodology used commercially available starting materials and afforded various 2,3,5‐triarylfurans. [ABSTRACT FROM AUTHOR]

Benzo[b]phosphole oxides are valuable and significant organic functional molecules. Therefore, extensive efforts have been dedicated to the development of an environmentally friendly and convenient synthetic strategy for benzo[b]phosphole oxides. However, several critical issues still persist in the currently available protocols. In this study, we present a direct air-oxidized strategy enabling the transformation of arylphosphine oxides into phosphinoyl radicals, which were further utilized in the synthesis of benzo[b]phosphole oxides by combining with various alkynes. In addition, the results of DFT calculations show that phosphinoyl radical formation could involve an O2-mediated O–H bond homolysis instead of the commonly recognized P–H bond homolysis mechanism. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis has emerged as a powerful and sustainable technique in organic synthesis; however, the application of graphitic carbon nitride (g-C3N4) as a heterogeneous photocatalyst for organic transformations is still in its infancy. The development of novel organic transformations catalyzed by g-C3N4 is actively being pursued by chemists but it remains challenging. Herein, we describe a visible-light-driven g-C3N4-catalyzed atom transfer radical addition (ATRA) of alkynes to synthesize valuable (E)-β-thio/seleno vinylsulfones. This approach features heterogeneous photocatalysis, excellent regio- and stereoselectivities, 100% atom economy, a metal- and additive-free nature, and broad substrate scope covering (hetero)aryl and alkyl alkynes, especially the industrial feedstock propyne. Furthermore, this method can be applied to the late-stage functionalization of complex molecules. Notably, g-C3N4 can be recovered and reused in five runs without loss of catalytic activity. Mechanistic studies demonstrate that the reaction occurs via an energy transfer process rather than single electron transfer. [ABSTRACT FROM AUTHOR]

An efficient strategy towards stereoselective amidation of alkynes is reported. The given method features operational simplicity, excellent functional group tolerance, broad substrate scope and fast kinetics to furnish Z-enamides. Moreover, the method was successfully applied for the facile synthesis of the natural products lansiumamide A, lansiumamide B and Z-alatamide. Notably, DMSO plays two vital roles: hydrogen source and solvent. [ABSTRACT FROM AUTHOR]

A novel metal‐ and oxidant‐free electrooxidative selenylamination of o‐aminophenacetylenes with diselenides for achieving 3‐selenylindoles has been developed with moderate to excellent yield. The reaction proceeded smoothly with a broad substrate scope and highly functional group tolerance. The synthetic practicality of this innovative approach was demonstrated by its easy scalability. Moreover, mechanistic studies revealed that an in‐situ generated selenium cation might be the key intermediate for the electrochemical selenocyclization process. [ABSTRACT FROM AUTHOR]