Activity assays of NnlA homologs suggest the natural product N-nitroglycine is degraded by diverse bacteria

• Kara A. Strickland,
• Brenda Martinez Rodriguez,
• Ashley A. Holland,
• Shelby Wagner,
• Michelle Luna-Alva,
• David E. Graham and
• Jonathan D. Caranto

Beilstein J. Org. Chem. 2024, 20, 830–840, doi:10.3762/bjoc.20.75

• protect bacteria from exposure to NNG. Keywords: enzymology; natural products; nitramine; N–N bond; Introduction Degradation of nitramines (R–N(R′)NO2; R′ = H or alkyl) has been well studied in the context of the environmental degradation of explosive cyclic nitramines [1][2]. The cyclic nitramines

Identification of the p-coumaric acid biosynthetic gene cluster in Kutzneria albida: insights into the diazotization-dependent deamination pathway

• Seiji Kawai,
• Akito Yamada,
• Yohei Katsuyama and
• Yasuo Ohnishi

Beilstein J. Org. Chem. 2024, 20, 1–11, doi:10.3762/bjoc.20.1

• the ANS pathway, it has been shown that the ANS pathway is involved in the nitrogen–nitrogen (N–N) bond formation in the biosynthesis of several natural products [6][7][8]. Enzymes that catalyze N–N bond formation by using nitrous acid from the ANS pathway have also been characterized in several

Synthesis of N-phenyl- and N-thiazolyl-1H-indazoles by copper-catalyzed intramolecular N-arylation of ortho-chlorinated arylhydrazones

• Yara Cristina Marchioro Barbosa,
• Guilherme Caneppele Paveglio,
• Claudio Martin Pereira de Pereira,
• Sidnei Moura,
• Cristiane Storck Schwalm,
• Gleison Antonio Casagrande and
• Lucas Pizzuti

Beilstein J. Org. Chem. 2022, 18, 1079–1087, doi:10.3762/bjoc.18.110

• cycloaddition reaction of α-diazomethylphosphonates with o-(trimethylsilyl)phenyl triflate in the presence of CsF [13], Cu2+-mediated N−N bond formation from ketimines in the presence of oxygen [14], Pd2+-mediated oxidative benzannulation from pyrazoles and internal alkynes [15], Pd-catalyzed Aza–Nenitzescu

New azodyrecins identified by a genome mining-directed reactivity-based screening

• Atina Rizkiya Choirunnisa,
• Kuga Arima,
• Yo Abe,
• Noritaka Kagaya,
• Kei Kudo,
• Hikaru Suenaga,
• Junko Hashimoto,
• Manabu Fujie,
• Noriyuki Satoh,
• Kazuo Shin-ya,
• Kenichi Matsuda and
• Toshiyuki Wakimoto

Beilstein J. Org. Chem. 2022, 18, 1017–1025, doi:10.3762/bjoc.18.102

• the prediction of the producer of natural products with the functional groups of interest, leading to a higher rate of hits. We recently exploited genome mining targeting hydrazine synthetase and the generation of inorganic hydrazine N2H4 in acid hydrolysate as an indicator of N–N bond-containing

• the discovery of N–N bond-containing natural products from our in-house actinobacterial culture collection, we found two closely related potential biosynthetic gene clusters of aliphatic azoxy natural products in Streptomyces sp. RM72 and Streptomyces sp. A1C6 (Figure 2 and Tables S1 and S2 in

Hydrazides in the reaction with hydroxypyrrolines: less nucleophilicity – more diversity

• Dmitrii A. Shabalin,
• Evgeniya E. Ivanova,
• Igor A. Ushakov,
• Elena Yu. Schmidt and
• Boris A. Trofimov

Beilstein J. Org. Chem. 2021, 17, 319–324, doi:10.3762/bjoc.17.29

• emphasis on the nature of hydrazine derivatives still remains obscure. Meeting this challenge becomes particularly important in view of the significance of the less nucleophilic hydrazides as N–N-bond containing starting materials in drug discovery [13][14][15][16]. Herein, we report how a lower

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• radicals with the formation of a C–O bond (dimer 4b, oxidation of diisopropyl oxime 1b), an O–N bond (dimer 4c, oxidation of benzophenone oxime 1c), and an N–N bond (dimer 4d, oxidation of benzaldoxime 1d, see also [58]) was observed. As a rule, the initial dimers of iminoxyl radicals are unstable, which

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• -isomers are generally assumed to have an intrinsically higher electron density due to the disruption of the conjugation between the two rings of the azobenzene through the N=N bond. Moreover, the electronic properties of the inner substituent Y have been proven to be of strategic use in increasing the

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• (Figure 8c, step i). Coordination of Pd2+ to the azo moiety, combined with the strongly electron-donating pyrazole moiety, affords (Figure 8c, step ii) a system akin to push–pull azobenzenes, whose Z isomers can back-isomerize rapidly due to a reduced order of the N=N bond [52][53][54] (Figure 8c, step

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• substituting azobenzenes in the ortho-positions to the N=N bond with electron-withdrawing fluorine substituents [45][46], the red-shifting of the n→π* transitions enables selective addressing of both the E- and Z-isomer using visible light. Stabilization of the n-orbitals in the Z-isomers leads to a very high

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• coupling to a bulk gold surface via a conjugated linker over 11 bonds and 14 Å [11]. Thermal cis→trans isomerizations of azobenzenes are usually slow with half-lives of the trans-isomer within the range of hours to days at room temperature (parent azobenzene: 4–5 d at 25 °C) [12]. Rotation around the N=N

• bond is a symmetry-forbidden process and the slow isomerization proceeds via inversion at the N atoms [13]. The rate of isomerization is temperature dependent and follows a classical Arrhenius type behavior [12]. However, the rate and the mechanism change dramatically if the azobenzenes are

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• mean plane calculated through the C atoms of 0.014(2) and 0.009(2) Å. The N=N bond lengths of the azo group of 1.251(4) Å corresponds to literature values and the CNNC torsion angle amounts to 3.7(4)°, which proves that this unit is nearly coplanar. In contrast, the CCSC fragment is twisted by 22.9(3

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• hydroperoxide in dichloromethane at room temperature for 2 h, the respective diazo aromatic compound 6 could be obtained in 50% yield (Scheme 5). As can be seen, the reaction proceeded smoothly allowing formation of the new N=N bond without cleavage of the C–Se bond under the oxidant media and the presence of

Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

• Jan Szabo,
• Julian Greiner and
• Gerhard Maas

Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57

• two moieties is indicated by the long C–N bond “c” (as compared to the other C–N bonds in the triazole ring) and the endocyclic N–N bond, both of which have a high single-bond character. The influence of the substituents on the triazole ring of II and 7a on the bond lengths is moderate. The bond

Azobenzene-based inhibitors of human carbonic anhydrase II

• Leander Simon Runtsch,
• David Michael Barber,
• Peter Mayer,
• Michael Groll,
• Dirk Trauner and
• Johannes Broichhagen

Beilstein J. Org. Chem. 2015, 11, 1129–1135, doi:10.3762/bjoc.11.127

• of −143.3° and 23.8° at the N=N bond and at the second aromatic ring to the diazene unit, respectively. It should be noted that a water molecule is held by the peptide backbone in the gorge (2.6 Å to OH of T200 and 2.7 Å to CO of P202), which might have interactions with the diazene unit although the

Photoswitchable precision glycooligomers and their lectin binding

• Daniela Ponader,
• Sinaida Igde,
• Marko Wehle,
• Katharina Märker,
• Mark Santer,
• David Bléger and
• Laura Hartmann

Beilstein J. Org. Chem. 2014, 10, 1603–1612, doi:10.3762/bjoc.10.166

• azobenzene functionalized with an Fmoc-protected aminomethyl group and a carboxylic acid both para to the N=N bond was used as one building block during solid-phase polymer synthesis of precision glycomacromolecules (see AZO, Figure 1) [19][20][21][22]. The benzylamine fragment was favored over the

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

• Denisa Tarabová,
• Stanislava Šoralová,
• Martin Breza,
• Marek Fronc,
• Wolfgang Holzer and
• Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

• rotated around the N–N bond, with the torsion angle C3–N5–N6–C6 −77.0(2)°, while the N–N bond and adjacent C=C bonds are highly planar with torsion angles 174.09(15)° for C2–C3–N5–N6 and 177.71(16)° for N5–N6–C6–C7. Correspondent bond lengths in the molecule show only minor variations. Three carbonyl

Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives

• Zhi-Cong Geng,
• Jian Chen,
• Ning Li,
• Xiao-Fei Huang,
• Yong Zhang,
• Ya-Wen Zhang and
• Xing-Wang Wang

Beilstein J. Org. Chem. 2012, 8, 1710–1720, doi:10.3762/bjoc.8.195

• are of great importance in biological and medicinal chemistry (Figure 1) [1][2][3][4][5]. Besides, pyrazolidines are also important synthetic intermediates in organic chemistry. For instance, the N–N bond of pyrazolidines can be cleaved under reductive conditions to afford useful 1,3-diamines [6][7

Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

• Jaume García-Amorós and
• Dolores Velasco

Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113

• electron transfer from the alkoxy group to the pyridinium salt produces a partial breaking of the double N–N bond of the azo moiety, thereby facilitating the rotation around this bond to recover the more stable initial trans configuration in a quick fashion [56]. Type-II azoderivatives: photochromic

• distribution with a simple N–N bond, which seems to be the key to the fast thermal isomerisation kinetics observed. In this way, the rotation around the N–N bond facilitates the recovery of the more stable trans isomer (Figure 14) [46][59][60][61]. The completely different kinetic behaviours observed between

• clearly determined by the intimate mechanism through which the process takes place. This mechanism has attracted much attention for many years and has given rise to controversy. For the process, two different extreme mechanisms have been proposed (Figure 6); one involving a simple rotation around the N–N

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• -benzhydryl-5-methyl-1,3,4-oxadiazole (6) became one of the major products in the flow reactor under these reaction conditions. The resulting hydrazide 7 can be expected to have a weak N–N bond, however, the products obtained from the decomposition of diacylhydrazides are generally considered to arise via

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• herein report a detailed account of the synthetic methods available for 5-aminopyrazoles. As pyrazole derivatives do not exist in nature, probably, due to the difficulty in the construction of N–N bond by living organisms, their availability depends on the synthetic methods. A large number of synthetic

Review of “Stereochemistry Workbook, 191 Problems and Solutions” by K.-H. Hellwich and C. D. Siebert

• Roald Hoffmann

Beilstein J. Org. Chem. 2009, 5, No. 38, doi:10.3762/bjoc.5.38

• isomers of a [CoCl2(H2NNH2)(PPh3)2] complex are said to be not possible, those where the H2NNH2 would bridge trans-positions on the octahedral metal. Indeed, both statements make sense, but it would be interesting to mention why they are true (strain, the long N–N bond necessary). And how it is in the

m-Iodosylbenzoic acid – a convenient recyclable reagent for highly efficient aromatic iodinations

• Andreas Kirschning,
• Mekhman S. Yusubov,
• Roza Y. Yusubova,
• Ki-Whan Chi and
• Joo Y. Park

Beilstein J. Org. Chem. 2007, 3, No. 19, doi:10.1186/1860-5397-3-19

• . Background In recent years, iodoarenes have gained increasing importance because they are widely used as building blocks in organic synthesis. They are particularly important as indispensable substrates for numerous methods of N-N bond formation, [1][2] for the chemistry of heterocyclic [3] and