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[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]

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]

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 multicomponent synthesis of β‐enaminones is explored using nitroalkane as a reagent and a solvent. The one‐pot reaction of 1,3‐diketone, aldehyde, and amine using nitromethane as the solvent resulted β‐enaminones exclusively. When the same reaction was performed in nitroethane, however, lactone ring‐opening of coumarin moiety was observed, leading to the formation of hydroxy‐β‐enaminones. The possible mechanisms for these reactions are deduced and the substrate scope of the reaction is investigated. The present investigation describes the multicomponent reaction of aldehyde, amine, and 1,3‐diketones in two different nitroalkane solvent systems. MCR reaction in nitromethane resulted in the formation of β‐enaminones exclusively. On the other hand, the same reaction if performed in nitroethane solvent, coumarin ring lactone opening was observed to yield the hydroxy‐β‐enaminones. The substrate scope and the possible mechanism of the present MCR are discussed herein. [ABSTRACT FROM AUTHOR]

Reactions of the type X• + HCR2CH2NO2 → XH + R2C=CH2 + N•O2 are exothermic, due to the breaking of weak C-N bonds and the formation of energy-intensive C=C bonds. Quantum chemistry calculations of the transition state using the reactions of Et• and EtO• with 2-nitrobutane shows that such reactions can be categorized as one-step, due to the extreme instability of the intermediate nitrobutyl radical toward decay with the formation of N•O2. Kinetic parameters that allow us to calculate the energy of activation and rate constant of such a reaction from its enthalpy are estimated using a model of intersecting parabolas. Enthalpies, energies of activation, and rate constants are calculated for a series of reactions with the participation of Et•, EtO•, RO•2, N•O2 radicals on the one hand and a series of nitroalkanes on the other. A new kinetic scheme of the chain decay of nitroalkanes with the participation of abstraction reactions with concerted fragmentation is proposed on the basis of the obtained data. [ABSTRACT FROM AUTHOR]

An efficient multicomponent reaction of nitroalkanes and elemental sulfur with oxiranes was developed with the aid of silver salt. This reaction procedure provides a novel and practical strategy for the rapid assembly of 1,3-oxathiolane skeletons. The reaction exhibited remarkable functional group tolerability and regio-selectivity so that only one regio-isomer formed during the ring opening of oxiranes. Graphical abstract: [ABSTRACT FROM AUTHOR]

A simple method via the base-catalyzed Michael addition of nitroalkanes to 2-iminochromenes was developed, which leads to the production of highly functionalized 2-amino-3-nitrile-4H-chromenes in good yields. [ABSTRACT FROM AUTHOR]

Keywords: nitroalkane; Ono-Tanner reaction; protodenitration; sustainable reduction; tributyltin hydride EN nitroalkane Ono-Tanner reaction protodenitration sustainable reduction tributyltin hydride 1 1 1 04/05/23 20230403 NES 230403 B The Front Cover b visually represents our review "The Last Fortress of Tin's Tyranny - Protodenitration of Nitroalkanes". Nitroalkane, Ono-Tanner reaction, protodenitration, sustainable reduction, tributyltin hydride Could the end of the last fortress of the tyranny of tin be in sight?" This review provides the historical development and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. [Extracted from the article]

4-Aryl-NH-1,2,3-triazoles are valuable compounds in organic chemistry and pharmaceutical chemistry. In this paper, we describe a novel multicomponent reaction of aldehydes, nitroalkanes, and sodium azide for the synthesis of 4-aryl-NH-1,2,3-triazoles. In this transformation, it was found that both the slow addition of nitroalkane and the presence of NaHSO3/Na2SO3 are advantageous to promote the reaction results. Additionally, a series of aldehydes and nitro compounds were investigated. [ABSTRACT FROM AUTHOR]

The non-empirical (MP2 and CCSD), composite (G4), and DFT (B3LYP, CAM-B3LYP, B98, and wB97XD) methods with different basis sets have been employed to compute the formation enthalpies of a series of C-C nitroalkanes and the hydrocarbon radicals formed via the C-N bond rupture as well as the C-N bond dissociation energies. For the series of isomeric nitroalkanes, the effects of the nature of the participating carbon atom (primary, secondary, or tertiary) and the size of adjacent alkyl group on the C-N bond strength have been analyzed. The reasons for different thermochemical and kinetic estimates of the C-N bond dissociation energy in nitroalkanes have been discussed. [ABSTRACT FROM AUTHOR]

An efficient and straight forward procedure for the syntheses of bicyclic isoxazole/isoxazoline derivatives from the corresponding dimethyl-2-(2-nitro-1-aryl/alkyl)-2-(prop-2-yn-1yl)malonates or dimethyl 2-allyl-2-(2-nitro-1-aryl/alkyl ethyl)malonate is described. High yields and simple operations are important features of this methodology. [ABSTRACT FROM AUTHOR]

The pyrrolidine-camphorsulfonamide-based catalyst 1a catalyzes the enantioselective conjugate addition of nitroalkanes to α,β-unsaturated aldehydes in the presence of five equivalents of water in iPrOH to give the corresponding chiral Michael adducts in good yields and high enantioselectivities (up to 99% ee) with a catalyst loading as low as 1 mol%. [ABSTRACT FROM AUTHOR]

Hochselektiv: Die Reduktion von α ‐ Methyl ‐ substituierten Nitroalkenen gelingt in hochenantioselektiver Weise bei Einsatz einer En ‐ Reduktase aus Gluconobacter oxydans. Unter optimierten Reaktionsbedingungen werden in diesen Biotransformationen die gewünschten Nitroalkane mit Enantiomerenüberschüssen von bis zu 95% ee gebildet (siehe Schema). [ABSTRACT FROM AUTHOR]

Tuberculosis is difficult to cure, requiring a minimum of 6 months of treatment with multiple antibiotics. Small numbers of organisms are able to tolerate the antibiotics and persist in the lungs of infected humans, but they still require some metabolic activity to survive. We studied the role of the hypoxia-induced Rv1894c gene in Mycobacterium tuberculosis virulence in guinea pigs, which develop hypoxic, necrotic granulomas histologically resembling those in humans and found this gene to be necessary for full bacillary growth and survival. We characterized the function of the encoded enzyme as a nitronate monooxygenase, which is needed to prevent the buildup of toxic products during hypoxic metabolism and is negatively regulated by the transcriptional repressor KstR. Future studies will focus on developing small-molecule inhibitors that target Rv1894c and its homologs, with the goal of killing persistent bacteria, thereby shortening the time needed to treat tuberculosis. [ABSTRACT FROM PUBLISHER]

An efficient Henry reaction has been described for the synthesis of 3-hydroxy-3-(nitroalkyl)-2-oxindole by the reaction of isatins with nitroalkanes in N,N-dimethylformamide (DMF) under anhydrous condition. This method provides high yield of 3-hydroxy-2-oxindoles under mild reaction condition. Moreover, the procedure is environmentally benign in nature, efficient, and applicable to variety of isatins as well as nitroalkanes. [ABSTRACT FROM PUBLISHER]

An operationally simple method has been developed for the conjugate addition of nitroalkanes to β-nitrostyrene with the use of thiourea catalysis. The reaction affords good yields of syn-1,3-dinitro adducts with only 2% catalyst loading. [ABSTRACT FROM AUTHOR]

2-Nitroalkanols can be efficiently synthesized using imidazole as a mild Lewis basic catalyst in aqueous medium as well as in organic solvents. The products have been found in good yields without purification (> 95% purity by 1H NMR) for aromatic aldehydes. Additionally, the very mild reaction conditions prevent the particular side reactions such as aldol condensation, Cannizzaro reaction, or dehydration of the 2-nitro alcohols into nitro alkenes even if aromatic aldehydes are used. This report satisfies the criteria for green synthesis in terms of reaction medium and recycling of the catalyst (imidazole). [ABSTRACT FROM AUTHOR]

The rates of racemization of optically active nitropentanoic acid, and 4-deuteronitropentanoic have been compared. The rate ratio (kie) is kH/kD = 5.68(±0.17) at 31°C, in good agreement with that determined by Lewis et al. for base-catalysed deprotonations using iodine-trapping methods. In a more detailed study, optically active 4-nitro-4-phenylbutanoic acid (NPBA) has also been prepared and rates of racemization measured in dimethoxyethane:water. With less than a full equivalent of triethylamine, rates are proportional to [Et3N:]/[NPBA]. For 1 < [Et3N:]/[NPBA] < 2, rates are independent of the ratio, consistent with racemization being dominated by deprotonation of the nitroalkane by the intramolecular carboxylate group. The solvent isotope effect is $k^{ {\rm \bf H}_{\bf 2} {\rm \bf O}} /k^{{\rm \bf D}_2 {\rm \bf O}} $ = 0.73(±0.04) and rates of exchange with D2O are equal to rates of racemization. Comparison with rates of racemization by acetate of the methyl ester yielded an effective molarity (EM = 13.7) for the intramolecular carboxylate. The kie for racemizations of NPBA and 4-deutero-NPBA is kH/kD = 5.78 at 25°C, and for 20 < T < 50°C, EaD - EaH = 5.5(±0.1) and AH/AD = 0.63(±1.03). For the acetate catalysed racemizations of the methyl ester, 25°C, kH/kD = 7.43 with EaD - EaH = 5.2 kJ mol-1 and AH/AD = 1.08. In neither case is there any indication of a major tunnelling contribution on the isotopic rate ratio. A hitherto unrecognised mode of decomposition of nitronic acids, involving direct reaction with dissolved oxygen, has been identified. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We describe a practical synthesis of (+)-9a-epi-stemo�amide, which has been achieved in six steps from α,β-unsaturated γ-butyrolactone. The main features of the current approach include a DBU-catalyzed Michael addition of nitroalkane and a reductive lactamization of nitro esters. [ABSTRACT FROM AUTHOR]

A microwave-assisted synthesis of γ-nitro acetamido esters, under mild conditions and without solvent, is described. The desired products were obtained via Michael additions from the commercial methyl acetamidoacrylate and nitroalkanes. [ABSTRACT FROM AUTHOR]