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The evolution of catalysis and functional group transfer reagents play a significant role in the development of anti‐Markovnikov alkene hydrofunctionalization reactions, facilitating the access to value‐added molecules. We herein report the first rational design of a modular intermolecular anti‐Markovnikov hydronitration of alkenes, enabling the direct synthesis of terminal nitroalkanes under visible light‐mediated photoredox catalysis. By employing the redox‐active organic nitrating reagent N‐nitrosuccinimide, the produced nitryl radicals, in the presence of an olefin and a hydrogen atom transfer (HAT) mediator, lead to an anti‐Markovnikov addition with complete regioselectivity. Furthermore, we present results demonstrating the use of this catalytic system for chain expansion via anti‐Markovnikov addition, utilizing substituted bromonitroalkanes as commercially available reagents. These transformations effectively address a gap in synthetic chemistry, enabling the direct synthesis of nitroalkanes from a variety of unactivated olefins in both complex molecules and unfunctionalized commodity chemicals. [ABSTRACT FROM AUTHOR]

This study reports the copper‐catalyzed α‐indolmethylation of 2‐pyridylacetates with 3‐indoleacetic acids. This reaction offers an approach to generating alkylideneindolenine electrophiles via the oxidative decarboxylation of 3‐indoleacetic acids. The developed reaction system demonstrates good versatility, extending beyond the indolmethylation of 2‐pyridylacetates to include activated esters and nitroalkanes. Moreover, a biological evaluation revealed that several products exhibited antiproliferative activity against different cancer cell lines. [ABSTRACT FROM AUTHOR]

The mechanism of acylamination of arenes with nitroalkanes in polyphosphoric acid has been clarified. The influence of the concentration of polyphosphoric acid, the structure of the starting compounds, and temperature on the result of the Beckmann rearrangement, which makes it possible to shift the reaction towards either benzamides or anilides, has been assessed. [ABSTRACT FROM AUTHOR]

α‐Aryl substituted nitroalkanes are valuable synthetic building blocks that can be easily converted into α‐aryl substituted aldehydes, ketones, carboxylic acids, as well as amines. Herein, an efficient Cu/oxalamide‐catalyzed coupling between nitroalkanes and (hetero)aryl halides (Br, I) was developed to direct access highly diverse α‐aryl substituted nitroalkanes. Compared with the current state of art, this protocol is more environmentally friendly and practical for synthetic chemists. This approach is characterized by a broad substrate scope on both nitroalkane part (primary nitroalkanes and nitromethane) and sp2 halide part ((hetero)aryl bromides/iodides and alkenyl bromides/iodides). The excellent functional group tolerance was observed, which would enable real world synthetic applications. More importantly, TON of current transformation reached to 3640, when some aryl iodides were used as coupling partners. This represents currently the highest catalyst turnover for transition‐metal catalyzed α‐arylation of nitroalkanes. Furthermore, the successful application in late‐stage modification of complex molecules and synthesis of a known retinoid X receptor (RXR) antagonist exemplified its synthetic potential. [ABSTRACT FROM AUTHOR]

The limited nucleophilic character and the bidentate nature of unactivated nitroalkane anions (nitronates) makes the corresponding alkylation and allylation procedures rather troublesome. This aspect is in sharp contrast with other commonly employed processes involving nitronate anions such as conjugate additions or nitroaldol reactions. This review summarizes the most rewarding approaches that along the years have been devised to overcome this limitation. Efficient methods are nowadays mainly based on metal‐catalyzed processes involving purely ionic or mixed ionic‐radical intermediates including photoenzymatic reactions. [ABSTRACT FROM AUTHOR]

In this study, we investigate the autodetachment dynamics of the 1-nitropropane anion after vibrational excitation of the energetically lowest C–H stretching mode using our recently developed extended quantum classical surface hopping approach including the detachment continuum. Therein the detachment from an electronic bound anion state is treated as a nonadiabatic transition into discretized detachment continuum states for an ensemble of classical nuclear trajectories propagated on quantum mechanical potential energy surfaces. The initial ensemble is obtained by sampling a phase space distribution accounting for the vibrational excitation of the C–H stretching mode of the molecule to match the experimental conditions. The simulated kinetic energy distribution of the ejected electrons reproduces characteristic features of the available experimental data. Analysis of the nuclear dynamics points out that the approach to neutral-like geometries with decreased pyramidalization angle of the NO 2 group and reduced the N–O bond lengths are the crucial factors enhancing the ultrafast autodetachment process in vibrationally excited 1-nitropropane. This is facilitated when the dipole-bound first excited state of the anion is populated, which is structurally similar to the neutral system. Although only a small transient population of this state is observed, it acts as an efficient doorway to the detachment continuum and is responsible for a significant amount of the ejected electrons. [ABSTRACT FROM AUTHOR]

Thioamides are an important, but a largely underexplored class of amide bioisostere in peptides. Replacement of oxoamide units with thioamides in peptide therapeutics is a valuable tactic to improve biological activity and resistance to enzymatic hydrolysis. This tactic, however, has been hampered by insufficient methods to introduce thioamide bonds into peptide or protein backbones in a site-specific and stereo-retentive fashion. In this work, we developed an efficient and mild thioacylation method to react nitroalkanes with amines directly in the presence of elemental sulfur and sodium sulfide to form a diverse range of thioamides in high yields. Notably, this convenient method can be employed for the controlled thioamide coupling of multifunctionalized peptides without epimerization of stereocenters, including the late stage thioacylation of advanced compounds of biological and medicinal interest. Experimental interrogation of postulated mechanisms currently supports the intermediacy of thioacyl species. Replacement of oxoamide units with thioamides in peptide therapeutics is a valuable tactic to improve biological activity and resistance to enzymatic hydrolysis. Here, the authors develop a direct coupling of readily available nitroalkane and amines with elemental sulfur and base and provide an efficient way to form thioamides and thiopeptides. [ABSTRACT FROM AUTHOR]

[11] The use of tin hydride is, however, associated with some drawbacks such as its bio- and ecotoxicity, [15] formation of inseparable tin-containing byproducts, necessity of fresh tin hydride to ensure high experimental reproducibility. Nitroalkane, 9-fluorenol, single-electron transfer, radical, organocatalysis, denitration [7] The emergence of alkyl radicals along with denitration is conventionally mediated by tin hydride in the presence of a radical initiator to result in reductive denitration (Scheme 1). Keywords: nitroalkane; 9-fluorenol; single-electron transfer; denitration; radical; organocatalysis EN nitroalkane 9-fluorenol single-electron transfer denitration radical organocatalysis 1482 1486 5 07/11/23 20230725 NES 230725 Graph Radical reactions are powerful methodology to construct complex carbon frameworks such as quaternary centers and fused rings serving important structural motifs for bioactive substances and advanced materials. [Extracted from the article]

Dynamic covalent gels are synthesized from an aromatic trialdehyde and α,ω‐dinitroalkanes via the nitroaldol reaction in organic solvents. The gelation process can be fine‐tuned by changing the starting nitroalkanes, solvents, feed concentration, catalyst loading, or reaction temperature. The resulting organogels demonstrate good structural integrity and excellent self‐healing ability. Intact xerogels are produced upon drying, without damaging the network, and the solvent‐free network can recover its gel form in the presence of an organic solvent. Furthermore, the crosslinked dynameric gel depolymerize to small molecules in response to excess nitromethane. [ABSTRACT FROM AUTHOR]

Herein we describe the enantioselective intermolecular conjugate addition of nitroalkanes to unactivated α,β‐unsaturated esters, catalyzed by a bifunctional iminophosphorane (BIMP) superbase. The transformation provides the most direct access to pharmaceutically relevant enantioenriched γ‐nitroesters, utilizing feedstock chemicals, with unprecedented selectivity. The methodology exhibits a broad substrate scope, including β‐(fluoro)alkyl, aryl and heteroaryl substituted electrophiles, and was successfully applied on a gram scale with reduced catalyst loading, and, additionally, catalyst recovery was carried out. The formal synthesis of a range of drug molecules, and an enantioselective synthesis of (S)‐rolipram were achieved. Additionally, computational studies revealed key reaction intermediates and transition state structures, and provided rationale for high enantioselectivities, in good agreement with experimental results. [ABSTRACT FROM AUTHOR]

An SbCl3-initiated C sp3 –C sp3 coupling between N -aryltetrahydroisoquinolines and nitromethanes was realized through the aerobic oxidation of sp 3 C–H bond, providing a series of nitromethylated tetrahydroisoquinoline derivatives in high yields. The results exhibited that SbCl3 , as a cheap and commercially available reagent, is an efficient initiator to promote the direct functionalization of sp3 C–H bond with broad functional group tolerance, which is potentially applied to a wider range of C–H bond activation reactions. [ABSTRACT FROM AUTHOR]

Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini‐review provides a historical development of the fundamental transformation and highlights the governing position of the Ono‐Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed "the last fortress of tin's tyranny." [ABSTRACT FROM AUTHOR]

Starting from commercially available ketones, a reproducible and reliable strategy for the synthesis of tetrasubstituted nitroalkenes was successfully developed, using a two-step procedure; the HWE olefination of the ketone to form the corresponding α,β-unsaturated esters is followed by a nitration reaction to introduce the nitro group in the α position of the ester group. The enantioselective organocatalytic reduction of these compounds has also been preliminarily studied, to access the functionalized enantioenriched nitroalkanes, which are useful starting materials for further synthetic elaborations. The absolute configuration of the reduction product was established by chemical correlation of the chiral nitroalkane with a known product; preliminary DFT calculations were also conducted to rationalize the stereochemical outcome of the organocatalytic enantioselective reduction. [ABSTRACT FROM AUTHOR]

Cyclohexylamine was found to be an efficient organocatalyst for the synthesis of structurally diverse 2-amino- 4H-chromenes by multicomponent reaction of (substituted) salicylaldehydes, active methylene compounds and nitroalkanes at ambient temperature and under solvent-free conditions. The synthesis of a variety of 2- amino-4H-chromenes was achieved using the reaction of (substituted) salicylaldehydes with two different C-H acids. The present protocol, which employed commercially available cyclohexylamine as an organocatalyst, offered the advantages of operational simplicity and avoidance of conventional purification methods and the obtained products were essentially pure. [ABSTRACT FROM AUTHOR]

The first examples of highly effective Henry reactions between nitroalkanes and aldehydes or trifluoromethyl ketones that proceed under catalyst-free and additive-free conditions, in a recyclable tap water medium, and at room temperature are reported. This process tolerates a broad range of aldehydes and trifluoromethyl ketones to give a series of β-nitro alcohol products in excellent yields. Such products are widely used in the syntheses of pharmaceutical intermediates and natural products. This protocol can be successfully scaled up to a 50-mmol scale without a reduction in yield. Tap water from different locations in China exhibited pH values ranging from 7.5 to 8.1, but the varying pH had no effect on the yield and the processes were successfully reproduced. Finally, the tap water was effectively recovered and reused without any postprocessing, even when the reaction substrates were different. [ABSTRACT FROM AUTHOR]

A Pd‐catalyzed Mizoroki‐Heck annulation/equivalent aminocarbonylation reaction of alkene‐tethered aryl iodides with nitro compounds is accomplished, providing facile access to diverse carbamoyl‐substituted benzoheterocycles, such as indolin‐2‐ones and 2,3‐dihydrobenzofurans, in moderate to good yields. The cost‐effective Mo(CO)6 complex is discovered to be a solid carbonyl (CO) source and an ideal reducing agent, enabling the efficient production of the desired benzoheterocycles with broad substrate scope tolerance, including both nitroarenes and nitroalkanes under external reductant‐free conditions. [ABSTRACT FROM AUTHOR]

The efficiency of an amino imidate organocatalyst was evaluated in the Michael reaction of ketones with nitroalkenes. tert-Butyl­ l-proline imidate was found to be a syn-selective catalyst, generating products with moderate to good enantioselectivities of up to 84% ee. The best substrates were found to be cyclic ketones and β-nitrostyrenes. The catalytic efficiency and enantioselectivity were enhanced by the addition of 10 mol% of benzoic acid.

Recursive Anionic Cyclization (RAC) continues to proliferate as a mechanistically distinct domino strategy. Deployment of nitroalkanes as a source of recursive carbanions has created a niche operating space for generating molecular complexity and diversity. This new corollary i. e. recursive nitronate cyclization is the basis of a domino [5 C+1 C] cyclization strategy wherein nitroalkanes act as one‐carbon lynchpin, providing rapid access to topologically intriguing, densely functionalized carbo‐ and heterocycles embodying multiple chiral centers with regio‐, stereo‐ and enantioselectivity. Extension to aromatic domains, particularly via benzannulation reactions, has further consolidated the operating space. While leveraging the functional versatility of nitro group for post‐domino modifications, such endeavors have culminated in total synthesis of diverse natural products. An incisive analysis of recursive nitronate cyclizations and their emergent potentials is delineated in this review. It is hoped that this focused narrative will enthuse and draw new practitioners to the arena to advance the field. [ABSTRACT FROM AUTHOR]

A practical protocol for the synthesis of ketones by Pd‐catalyzed cross‐coupling of phenol derivatives with nitroalkanes followed by a Nef‐type reaction has been developed. The readily available nitroalkanes served as alkyl nucleophiles under basic conditions to couple with easy‐to‐handle phenol derivatives derived from naturally abundant phenols. The avoidance of using organometallics and organic halides makes this protocol more sustainable. The reaction was compatible with various functional groups, including nitro, cyano, acetyl, aldehyde, halide, and ester groups. Furthermore, the successful application of our method in drug synthesis exemplified its synthetic potential in pharmaceutical sciences. Preliminary mechanistic investigations strongly suggested the possible involvement of α‐aryl‐substituted nitroalkane intermediates. [ABSTRACT FROM AUTHOR]

A synthesis of 3-alkyl-2-arylindoles was performed by sequential oxidation and reduction of 2-(2-nitrophenyl)ethanols that were prepared by base-catalyzed three-component reactions of vinylarenes, aldehydes, and various pronucleophiles, including nitroalkanes, thiols, and malonates. In addition to indoles, a selective synthesis of an N -hydroxyindole was accomplished. The highly nucleophilic character of transient benzylic anions in DMSO was also clarified for the three-component reactions. [ABSTRACT FROM AUTHOR]

Decarboxylative transformations of paraconic acids, a class of γ-butyrolactones containing a carboxylic acid group at the β-position as their characteristic functionality, by using a combination of AgNO3 /K2 S2 O8 were investigated. The dual function of AgNO3 as an initiator of the decarboxylation process and as a source of nitrogen dioxide radicals that react with aliphatic carboxylic substrates is reported for the first time. Starting from paraconic acids, β-nitro- and β-hydroxy γ-butyrolactones were obtained in good combined yields (41–85%) with moderate selectivity in a one-pot operation. The reactions were completed within an acceptable reaction time (two hours) under mild conditions that were tolerated by the γ-butyrolactone core. This study provides a direct and site-specific entry to β-nitro- and β-hydroxy γ-butyrolactones, which are important precursors in organic transformations. [ABSTRACT FROM AUTHOR]

A method for the synthesis of 2-(2-acylaminoaryl)quinolines was developed based on a one-pot sequence of direct electrophilic acylamination of arenes with nitroalkanes in polyphosphoric acid and acylation at the ortho position with respect to the acylamino group. [ABSTRACT FROM AUTHOR]

Synthetic methods that enable simultaneous control over multiple stereogenic centers are desirable for the efficient preparation of pharmaceutical compounds. Herein, we report the discovery and development of a catalyst-mediated asymmetric Michael addition/crystallization-induced diastereomer transformation of broad scope. The sequence controls three stereogenic centers, two of which are stereochemically labile. The configurational instability of 1,3-dicarbonyls and nitroalkanes, typically considered a liability in stereoselective synthesis, is productively leveraged by merging enantioselective Brønsted base organocatalysis and thermodynamic stereocontrol using a single convergent crystallization. The synthesis of useful g-nitro b-keto amides containing three contiguous stereogenic centers is thus achieved from Michael acceptors containing two prochiral centers. [ABSTRACT FROM AUTHOR]

A highly efficient and expeditious one-pot approach towards 2-(3-oxoindolin-2-yl)acetonitriles was designed, which involves a base-assisted aldol reaction of ortho-nitroacetophenones, followed by hydrocyanation, triggering an unusual reductive cyclization reaction. [ABSTRACT FROM AUTHOR]

An efficient method for the construction of 1,2‐oxazine N‐oxides has been developed via Pd‐catalyzed chemoselective bis‐allylic substitution of 2‐methylenepropane‐1,3‐diol dicarbonates with arylated nitroalkanes through sequential C‐ and O‐nucleophilic allylic substitution in one‐pot manipulation. By using Pd(PPh3)4 as a catalyst under mild reaction conditions, the process allows rapid access to 3‐aryl‐5,6‐dihydro‐4H‐1,2‐oxazine N‐oxides in high yields with excellent chemoselectivities. [ABSTRACT FROM AUTHOR]

3-(1H-Indol-3-yl)benzofuran-2(3H)-ones were efficiently accessed via polyphosphoric acid-mediated condensation of 3-(2-nitrovinyl)-1H-indoles with phenols. [ABSTRACT FROM AUTHOR]

Three aliphatic nitroalkanes, nitromethane, nitroethane, and 1-nitropropane, are investigated with fs laser-induced filament and breakdown spectroscopy (LIFBS). Filament emission spectra, C I, the CN violet system (B2Σ+ − X2Σ+, Δν = 0 sequence), and the C2 swan system (d3Πg − a3Πu, Δν = 0 sequence), are obtained. The time integrated intensities of CN and C2 can be used for identifying the three nitroalkanes. The filament features (length, diameter, and temperature) of the CN and C2 emissions are analyzed; C2 converts to CN through a single-atom substitution reaction between C2 and N atoms at the early stage, which mainly occurs at the head and tail parts of the filament with a lower temperature rather than at the hotter middle part. [ABSTRACT FROM AUTHOR]

Novel preparative approach for the synthesis of alkylamines with 1,3,4-oxadiazole heterocyclic substituent is described. This method is based on unusual cascade transformation involving formal (4+1) cyclocondensation of hydrazides of amino acids with nitroalkanes electrophilically activated in the presence of polyphosphoric acid. [ABSTRACT FROM AUTHOR]

Nitroalkanes are organic aliphatic hydrocarbon compounds with a nitro moiety that are commonly used as solvents or intermediates to synthesize a variety of organic compounds due to their inherent reactivity. In June 2020, a harmonized classification and labeling (CLH) proposal was submitted to the European Chemicals Agency (ECHA) for the following harmonized carcinogenicity, mutagenicity, and reproductive toxicity ("CMR") classifications for nitromethane (NM), nitroethane (NE), and 1‐nitropropane (1‐NP): NM Carc. 1B and Repr. 1B; NE Repr. 1B; and 1‐NP Repr. 2. In this assessment, a weight of evidence (WoE) evaluation of studies on animal carcinogenicity and reproductive and developmental toxicity, genotoxicity, and mode of action for these three nitroalkanes was performed to critically assess the relevance of the proposed CMR classifications. Overall, the WoE indicates that NM, NE, and 1‐NP are not carcinogenic, genotoxic, nor selective reproductive or developmental toxicants. Based on our analysis, classifying NM, NE, and 1‐NP as Category 2 reproductive toxicants is most appropriate. Furthermore, not classifying NE and 1‐NP with respect to their carcinogenicity is appropriate based on the available studies for this endpoint coupled with negative results in genotoxicity studies, metabolism data, and in silico predictions. We determined that the classification for NM of Carc. 1B is not appropriate, based on the fact that rat mammary and harderian tumors are likely not relevant to humans and lung and liver tumors reported in mice were equivocal in their dose–response and statistical significance. A weight of evidence (WoE) evaluation of carcinogenicity and reproductive and developmental toxicity, genotoxicity, and mode of action for nitromethane (NM), nitroethane (NE), and 1‐nitropropane (1‐NP) was performed. The WoE indicates that NM, NE, and 1‐NP are not carcinogenic, genotoxic, nor selective reproductive or developmental toxicants. We recommend classifying NM, NE, and 1‐NP as Category 2 reproductive toxicants, and not classifying NE or 1‐NP with respect to their carcinogenicity; the ECHA proposed Carc. 1B classification for NM is not appropriate. [ABSTRACT FROM AUTHOR]

Imidazo[1,5-a]pyridines were efficiently prepared via the cyclization of 2-picolylamines with nitroalkanes electrophilically activated in the presence of phosphorous acid in polyphosphoric acid (PPA) medium.

In this paper, we present axisymmetric numerical simulations of shock propagation in nitromethane over an aluminum particle for post-shock pressures up to 10 GPa. We use the Mie-Gruneisen equation of state to describe both the medium and the particle. The numerical method is a finite-volume based solver on a Cartesian grid, that allows for multi-material interfaces and shocks, and uses a novel constrained reinitialization scheme to precisely preserve particle mass and volume. We compute the unsteady inviscid drag coefficient as a function of time, and show that when normalized by post-shock conditions, the maximum drag coefficient decreases with increasing post-shock pressure. We also compute the mass-averaged particle pressure and show that the observed oscillations inside the particle are on the particle-acoustic time scale. Finally, we present simplified point-particle models that can be used for macroscale simulations. In the Appendix, we extend the isothermal or isentropic assumption concerning the point-force models to non-ideal equations of state, thus justifying their use for the current problem. [ABSTRACT FROM AUTHOR]

Nitroalkanes such as nitromethane, nitroethane, 1-nitropropane (1NP), and 2-nitropropane (2NP), derived from anthropogenic activities, are hazardous environmental pollutants due to their toxicity and carcinogenic activity. In nature, 3-nitropropionate (3NPA) and its derivatives are produced as a defense mechanism by many groups of organisms, including bacteria, fungi, insects, and plants. 3NPA is highly toxic as its conjugate base, propionate-3-nitronate (P3N), is a potent inhibitor of mitochondrial succinate dehydrogenase, essential to the tricarboxylic acid cycle, and can inhibit isocitrate lyase, a critical enzyme of the glyoxylate cycle. In response to these toxic compounds, several organisms on the phylogenetic scale express genes that code for enzymes involved in the catabolism of nitroalkanes: nitroalkane oxidases (NAOs) and nitronate monooxygenases (NMOs) (previously classified as nitropropane dioxygenases, NPDs). Two types of NMOs have been identified: class I and class II, which differ in structure, catalytic efficiency, and preferred substrates. This review focuses on the biochemical properties, structure, classification, and physiological functions of NMOs, and offers perspectives for their in vivo and in vitro applications. Key points: • Nitronate monooxygenases (NMOs) are key enzymes in nitroalkane catabolism. • NMO enzymes are involved in defense mechanisms in different organisms. • NMO applications include organic synthesis, biocatalysts, and bioremediation. [ABSTRACT FROM AUTHOR]

A new approach for highly selective monoalkylation of active methylene and related derivatives using various types of alkylsilyl peroxides in the presence of copper catalysts under mild conditions has been developed to a synthetically useful level. This approach has a wide substrate scope in terms of both active methylene compounds and alkylsilyl peroxides. In addition, nitroalkanes can also be employed for a copper‐catalyzed selective monoalkylation with alkylsilyl peroxides. The participation of radical species was proposed in the present monoalkylation reactions by the mechanistic study. [ABSTRACT FROM AUTHOR]

An iridium-catalyzed highly chemoselective and efficient transfer hydrogenation reduction of structurally diverse nitroalkenes was realized at very low catalyst loading (S/C = up to 10000 or 20 000), using formic acid or sodium formate as a traceless hydride donor in water. Excellent functionality tolerance is also observed. The turnover number and turnover frequency of the catalyst reach as high as 18 600 and 19 200 h−1, respectively. An inert atmosphere protection is not required. The reactivities of nitroalkenes are dependent on their substitution pattern, and the pH value is a key factor to accomplish the complete conversion and excellent chemoselectivity. Purification of products is achieved by simple extraction without column chromatography. The reduction procedure is facilely amplified to 10 g scale at 10 000 S/C ratio. The potential of this green reduction in enantioselective hydrogenation has been demonstrated. [ABSTRACT FROM AUTHOR]

Chiral phase‐transfer catalysis provides high level of enantiocontrol, however no experimental data showed the interaction of catalysts and substrates. 1H NMR titration was carried out on Cinchona and Maruoka ammonium bromides vs. nitro, carbonyl, heterocycles, and N−F containing compounds. It was found that neutral organic species and quaternary ammonium salts interacted via an ensemble of catalyst +N−C−H and (sp2)C−H, specific for each substrate studied. The correspondent BArF salts interacted with carbonyls via a diverse set of +N−C−H and (sp2)C−H compared to bromides. This data suggests that BArF ammonium salts may display a different enantioselectivity profile. Although not providing quantitative data for the affinity constants, the data reported proofs that chiral ammonium salts coordinate with substrates, prior to transition state, through specific C−H positions in their structures, providing a new rational to rationalize the origin of enantioselectivity in their catalyses. [ABSTRACT FROM AUTHOR]

A metal‐free, mild and chemodivergent transformation involving nitroalkanes has been developed. Under optimized reaction conditions, in the presence of trichlorosilane and a tertiary amine, aliphatic nitroalkanes were selectively converted into amines or nitriles. Furthermore, when chiral β‐substituted nitro compounds were reacted, the stereochemical integrity of the stereocenter was maintained and α‐functionalized nitriles were obtained with no loss of enantiomeric excess. The methodology was successfully applied to the synthesis of chiral β‐cyano esters, α‐aryl alkylnitriles, and TBS‐protected cyanohydrins, including direct precursors of four active pharmaceutical ingredients (ibuprofen, tembamide, aegeline and denopamine). [ABSTRACT FROM AUTHOR]

Fatty acid nitroalkenes are reversibly-reactive electrophiles that are endogenously detectable at nM concentrations and display anti-inflammatory, pro-survival actions. These actions are elicited through the alteration of signal transduction proteins via a Michael addition on nucleophilic cysteine thiols. Nitrated fatty acids (NO2-FAs), like 9- or 10-nitro-octadec-9-enolic acid, will act on signal transduction proteins directly or on key regulatory proteins to cause an up-regulation or down-regulation of the protein's expression, yielding an anti-inflammatory response. These responses have been characterized in many organ systems, such as the cardiovascular system, with the pulmonary system less well defined. Macrophages are one of the most abundant immune cells in the lung and are essential in maintaining lung homeostasis. Despite this, macrophages can play a role in both acute and chronic lung injury due to up-regulation of anti-inflammatory signal transduction pathways and down-regulation of pro-inflammatory pathways. Through their propensity to alter signal transduction pathways, NO2-FAs may be able to reduce macrophage activation during pulmonary injury. This review will focus on the implications of NO2-FAs on macrophage activation in the lung and the signal transduction pathways that may be altered, leading to reduced pulmonary injury. [ABSTRACT FROM AUTHOR]

Sequential acylation‐silylation of nitroalkanes leads to O‐silylated α‐acyloxyoximes in high yields. The first step of the reaction involves deprotonation of nitro compound with sodium hydride promoted by DBU or alcohol/15‐crown‐5 system followed by treatment with acyl chloride. In situ generated acyl nitronate is further silylated by silyl triflate that triggers hetero‐Claisen [3,3]‐rearrangement within N‐acyloxyenamine moiety furnishing orthogonally protected oxime derivatives. The procedure has large substrate scope for both nitroalkanes and acylating agents (acyl chlorides, chloroformates) and allows tuning of reaction conditions depending on the particular type of substrate. Application of obtained oxime derivatives in organic synthesis is demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] An expedient access to novel 4-phosphonomethyl-containing 2,6-disubstituted 4,5-dihydropyridazin-3(2 H)-ones involves the reaction of β-phosphono γ'-keto ester intermediates with hydrazines. The construction of the pyridazinone ring allows the installation of various substituents at the positions 2 and 6 as well as a valuable 4-positioned phosphonomethyl fragment. [ABSTRACT FROM AUTHOR]

A highly efficient and expeditious one-pot approach towards 2-(3-oxoindolin-2-yl)acetonitriles was designed, which involves a base-assisted aldol reaction of ortho-nitroacetophenones, followed by hydrocyanation, triggering an unusual reductive cyclization reaction.

3-(1H-Indol-3-yl)benzofuran-2(3H)-ones were efficiently accessed via polyphosphoric acid-mediated condensation of 3-(2-nitrovinyl)-1H-indoles with phenols.

Three-component reactions of nitroalkanes, acrylamides, and aldehydes by using a catalytic amount of KOH in DMSO gave β′-hydroxy-γ-nitro amides. Mechanistic studies suggested that the reactions proceeded by domino Michael/aldol reactions. The highly nucleophilic nature of transient amide enolates that were formed by Michael addition of nitronate anions to acrylamides in DMSO enabled the realization of catalytic intermolecular aldol reactions of amide enolates in the presence of acidic nitroalkanes. [ABSTRACT FROM AUTHOR]

We disclose a unprecedented riboflavin promoted Nef reaction of primary nitroalkanes coupled with a nitroaldol reaction. This tandem process allows the synthesis of functionalized nitro alcohols under mild reaction conditions. Secondary nitroalkanes fail to give the expected nitroaldol products although they are consumed under the reaction conditions. [ABSTRACT FROM AUTHOR]

A new and practical synthetic approach to construct 2-aryl-quinoline derivatives has been described through the sequential Aza-Henry (Nitro-Mannich) reaction using readily available 2,3-dihydro-1H-inden-5-amines, aldehydes and nitroalkanes under one-pot solvent-free reaction conditions using TsOH·H2O as the sustainable catalyst. In this regioselective approach, we described a cascade that proceeds through a sequential imine formation/Aza-Henry reaction/cyclization/denitration/rearrangement followed by oxidative aromatization to afford diverse 2-aryl-quinolines. This approach features large substrate scope, good functional group tolerance, mild reaction conditions and excellent yields with gram scale synthetic utility. [ABSTRACT FROM AUTHOR]

An environmentally friendly, straightforward, and cheap synthesis of highly substituted functionalized pyrrole derivatives via one pot four-component reactions of 1,3-dicarbonyl compounds, amines, aromatic aldehydes, and nitroalkanes have been developed. This methodology provides desired pyrroles in good-to-excellent yields in the presence of Fe (III)-Schiff base/SBA-15 as a heterogeneous catalyst. [ABSTRACT FROM AUTHOR]

Unusual reactivity of nitroalkanes, involving formation of aci-forms (nitronic acids or nitronates) and their subsequent interaction with carbon-based nucleophiles, is surveyed in this review.

A divergent photocatalytic system for the reaction of α-bromo nitroalkanes with styrene derivatives is established, wherein the generation of the persistent nitroxyl radical as a junctional intermediate and suitable tuning of the redox ability of the system constitute the crucial elements for achieving rigorous control over the possible reaction pathways. [ABSTRACT FROM AUTHOR]

New five‐membered cyclic nitrones with gem‐difluoroalkyl groups in γ‐position have been prepared by a 3‐step sequence starting from propargylic alcohols. This domino process involves a base‐mediated isomerization reaction to enones, which are trapped in situ by nitroalkane anions. In a final step, starting from these key precursors, a reduction‐cyclization process affords the target molecules. Mono‐ and bicyclic nitrones have been prepared by this route which allows, as well, the synthesis of nitrones with functional groups in terminal position of the side chain. [ABSTRACT FROM AUTHOR]

Unusual reaction proceeding via the electrophilic activation of nitroalkanes in the presence of polyphosphoric acid has been discovered. Subsequent nucleophilic attack with semicarbazides or thiosemicarbazides allows to access 2-amino-1,3,4-oxadiazoles and 2-amino-1,3,4-thiadiazoles, respectively. [ABSTRACT FROM AUTHOR]