Enantioselective synthesis of β-aryl-γ-lactam derivatives via Heck–Matsuda desymmetrization of N-protected 2,5-dihydro-1H-pyrroles

• Arnaldo G. de Oliveira Jr.,
• Martí F. Wang,
• Rafaela C. Carmona,
• Danilo M. Lustosa,
• Sergei A. Gorbatov and
• Carlos R. D. Correia

Beilstein J. Org. Chem. 2024, 20, 940–949, doi:10.3762/bjoc.20.84

• 4bo (o-phenoxy and o-bromo group, respectively), the er dropped considerably. Finally, a strong electron-withdrawing group in the ortho position such as nitro (4bn) was met with a decrease in yield (66%), but with a higher er. During the development of the scope, the hemiaminal ethers (Heck–Matsuda

Ortho-ester-substituted diaryliodonium salts enabled regioselective arylocyclization of naphthols toward 3,4-benzocoumarins

• Ke Jiang,
• Cheng Pan,
• Limin Wang,
• Hao-Yang Wang and
• Jianwei Han

Beilstein J. Org. Chem. 2024, 20, 841–851, doi:10.3762/bjoc.20.76

• explored the reactivity of ortho-functionalized diaryliodonium salts containing electron-withdrawing groups (EWGs) such as fluorine and nitro groups [29][30]. These ortho-substituted diaryliodonium salts undergo selective benzocyclizations and arylocyclizations with aromatic acids, leading to 3,4

• group (such as a nitro group) in the para position was reacted, the corresponding product could not be obtained, but instead the O-arylated product 3at was obtained (Table 2, entry 19). Apart from naphthol, we also tested substituted phenols under the standard conditions. The corresponding products of

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

• carcinogenicity [3][4][5][6][7][8]. Biotic and abiotic degradation of cyclic nitramines often produce linear nitramine byproducts. For example, degradation of RDX and HMX by microbes or alkaline hydrolysis forms the linear nitramine 4-nitro-2,4-diazabutanal (NDAB) [9][10][11][12]. Linear nitramines are also

• formation of propionate 3-nitronate (P3N) as a conjugate base (Scheme 2) [39]. It is P3N that directly reacts with a cysteine in the ICL1 active site, forming a thiohydroxamate adduct that inhibits ICL1 turnover [40]. Additionally, the nitronate form of nitro acids has been proposed to behave as a

• transition analog of carboxylate groups, resulting in nitro compounds also acting as tight-binding reversible inhibitors [42]. Deprotonation of NNG also results in formation of the corresponding nitronate, albeit with a pKa of 6.6 [24], far lower than that for 3-NP (Scheme 2). Therefore, a much larger

Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

Facile approach to N,O,S-heteropentacycles via condensation of sterically crowded 3H-phenoxazin-3-one with ortho-substituted anilines

• Eugeny Ivakhnenko,
• Vasily Malay,
• Pavel Knyazev,
• Nikita Merezhko,
• Nadezhda Makarova,
• Oleg Demidov,
• Gennady Borodkin,
• Andrey Starikov and
• Vladimir Minkin

Beilstein J. Org. Chem. 2024, 20, 336–345, doi:10.3762/bjoc.20.34

• (31), is formed between the nitro and imino groups of the N-aryl ring. The compounds 4a–h intensely absorb light in the spectral range of 400–550 nm, with maxima at 439–459 nm, ε = 20600–37100 M−1⋅cm−1 (Figure 3 and Table 1). The introduction of an amino group into the p-position of the N-phenyl

Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• yields than electron-donating groups (Scheme 2, 3aa–af). Remarkably, the nitro group gave the corresponding product 3ag in 94% yield. It was found that electron-donating groups afforded relatively higher dr values than electron-withdrawing groups (Scheme 2, 3aa–af). The effect of the R4 group was also

Substitution reactions in the acenaphthene analog of quino[7,8-h]quinoline and an unusual synthesis of the corresponding acenaphthylenes by tele-elimination

• Ekaterina V. Kolupaeva,
• Narek A. Dzhangiryan,
• Alexander F. Pozharskii,
• Oleg P. Demidov and
• Valery A. Ozeryanskii

Beilstein J. Org. Chem. 2024, 20, 243–253, doi:10.3762/bjoc.20.24

• quinolines, at the benzene ring, and the resulting nitro compounds could potentially be subjected to further transformations, including nucleophilic substitution of nitro groups. Indeed, under the action of a small excess of the nitrating mixture, dipyridoacenaphthene 5 undergoes double nitration at

• several minutes with a good yield (Scheme 4). The spectral data fully confirmed the purity and asymmetric structure of product 11. It should be emphasized that the isolation and purification of nitro compounds 10 and 11 is complicated by their low solubility in traditional organic solvents, sensitivity to

• sunlight (especially on adsorbents), and basic dipolar solvents (DMSO, for example, causes rather rapid degradation) [23]. Note that nitro derivatives 10 or 11 are not formed when base 5 is kept in nitric acid (25 °C, excess of 65% HNO3, 24 h) which returns the starting compound unchanged. After that step

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• -wavelength absorption bands with maxima in a range from λmax = 333 nm for the ethyl-substituted compound 2f to λmax = 394 nm for the nitro-substituted derivative 2a (Figure 1A, Supporting Information File 1, Table S1). As compared with the absorption maximum of the parent compound at λmax = 330 nm [20], the

• derivatives 2b–g showed a slight bathochromic shift mostly in the range of λmax = 333–360 nm, whereas for the nitro-substituted compound 2a a stronger red shift of the absorption maximum was observed, presumably caused by the strong electron-withdrawing property of the nitro group resulting in a more

• an exception, the irradiation of the nitro-substituted styrylpyridine derivative 2a in MeCN or H2O led to disappearance of the long-wavelength absorption maximum with no formation of a distinct new band (Figure 2A), which usually indicates photoinduced decomposition. This observation is in agreement

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• , resulting in glutarimides with a heterocyclic fragment at the α-position 1a–e – structures in demand for the design of CRBN ligands and immunomodulatory drugs. In compound 6n, catalytic hydrogenation was used to reduce the nitro group, resulting in the production of a benzotriazole analog of pomalidomide

A novel recyclable organocatalyst for the gram-scale enantioselective synthesis of (S)-baclofen

• Gyula Dargó,
• Dóra Erdélyi,
• Balázs Molnár,
• Péter Kisszékelyi,
• Zsófia Garádi and
• József Kupai

Beilstein J. Org. Chem. 2023, 19, 1811–1824, doi:10.3762/bjoc.19.133

• be synthesized in two steps. The nitro acid (S)-18 was obtained using HCl in THF in good yield (70%), which could be reduced to (S)-baclofen hydrochloride using Raney nickel as catalyst (Scheme 4) [38]. Conclusion In conclusion, we have prepared a new lipophilic cinchona squaramide organocatalyst 2

• g, 89%). Synthesis of nitro acid (S)-18 In a 150 mL pressure flask (Synthware), the baclofen precursor (S)-17 (0.5 g, 1.36 mmol) was dissolved in THF (71 mL), and 1 M HCl (aq. solution, 36 mL) was added. The reaction mixture was heated in a 100 °C oil bath for 5 hours. Then, the volatile components

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• /E isomers in approximately 85:15 ratio. The same spectra in CDCl3 showed broad coalescent signals for the characteristic vinyl CH protons, which is indicative of a dynamic equilibrium between the isomers. For both types of nitro intermediates 3 and 6 the final ring-forming step required reduction of

• the nitro group with subsequent cyclization of the reduced intermediate (Scheme 2, conditions iv). We tried to carry out these reactions either with Zn in acetic acid/dichloromethane or by transfer hydrogenation with ammonium formate in the presence of Pd on charcoal. Both types of reductive

• aromatic nitro derivatives 3 and 6 proceeds through the corresponding hydroxylamines, capable of intramolecular cyclization to products 4 or 7. Fortunately, under Zn/AcOH reductive conditions this was resolved by extending the duration of the reaction to 18–24 h, providing enough time for compounds 4/7 to

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• -acylhydrazones were synthesized and fully characterized, both in solution and in the solid state. The compounds differ with respect to the carbonyl precursors, i.e., 3-substituted salicylaldehydes with either a methyl or a nitro group. Single crystals of both compounds were isolated from the respective mother

• phenolic hydroxy group and the azomethine nitrogen was identified in the solid state and seems to be maintained in solution. Moreover, the presence of the electron-withdrawing nitro substituent makes this interaction stronger. However, the contact should probably not subsist for the nitro compound under

• display a role in neurodegeneration [38]. A comparative study between these two N-acylhydrazones is interesting, especially considering that they possess different substituents at the same position in the phenol ring: the electron-donating methyl group (hdz-CH3) and the electron-withdrawing nitro group

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• properties of Qx45 series by incorporating electron-donating (methyl) and electron-withdrawing groups (bromo and nitro) (Figure 6). The observation of low-lying LUMO levels (−3.29 to −3.43 eV) and thermal stability in these dyes suggested their potential as efficient ETMs [50]. Similarly, Singh et al

• . explored the modulation of optoelectrochemical properties and thermal characteristics of pyridopyrazino[2,3-b]indole-based Qx46 series with varying substituents, i.e., bromine, chlorine, methyl and nitro group. Their study revealed inbuilt ICT and aggregation-induced emission (AIE) effects, forming

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• increased to 99% when the reaction was run for 3 h. 2-Hydroxy-5-methoxybenzaldehyde in the reaction with rhodanine gave product 3e in a moderate 63% yield. The presence of an electron-withdrawing group such as a nitro did not seem to really decrease the reactivity as product 3f was obtained in 79% yield

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• ]. Moreover, sulfenylation of ketoximes and secondary nitro compounds toward N-arenesulfenyl ketimines occurred by applying N-(phenylthio)phthalimide [69]. In 2011, Shi et al. developed a method for the sulfenylation of unsaturated alcohols 86 by N-(benzylthio)succinimide 1 access to tetrahydrofurans 87 and

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• ) in Scheme 5, Scheme 6 and the Experimental section). There are some features of this cyclization. The electron-poor enones 2l,m are unreactive and do not give rise to the corresponding indanones due to the low nucleophilicity of the nitro-substituted aromatic ring. On the other hand, the electron

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• . Two complexes, 61 and 65 (see Scheme 21), were found equally efficient. The products were obtained in 95 to 99% yield and the range of functionalities tolerated included nitro, nitrile, ether, carbonyl, alcohol, and amine [35]. Gautier and co-workers studied the effect of the addition of aromatic N

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• -tetraarylporphyrins 1 were synthesized from the corresponding 2-nitro-meso-tetraarylporphyrins in two steps by following the literature procedure [42]. The first step involved an amination of copper(II) 2-nitro-meso-tetraarylporphyrins by using 4-amino-4H-1,2,4-triazole in the presence of NaOH in refluxing ethanol

• /toluene 1:10 mixture under inert atmosphere to afford 2-amino-3-nitro-meso-tetraarylporphyrins which on reduction through sodium borohydride in the presence of 10% Pd/C in CH2Cl2/MeOH provided the desired porphyrins 1 in good yields as key starting materials for the synthesis of newly designed benzo[f

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• substituent was present (31 vs 70), and the highest yield was found with ortho-nitro ylide derivative 71. Computational studies, using abridged ylide 72 and thioacetamide as model substrates, were also performed to better understand the mechanism, specifically exploring the role of the nitro group and the

• reductive elimination of the iodoarene (Figure 16). They found 72 to possess secondary intramolecular halogen bonding between the nitro group and iodine’s proximal (stronger) σ-hole. The reaction initiated by selectively forming adduct 73 between the thioamide and the ylide, which possessed both halogen

• comparing ylides 31 and 70 in this reductive elimination step, which suggested that the ortho-nitro group of 72 (and 71, by extension) played a role other than lowering the activation energy of this step. Given that other optimized halogen- and hydrogen-bonded conformations were found between thioamide and

Selective and scalable oxygenation of heteroatoms using the elements of nature: air, water, and light

• Damiano Diprima,
• Hannes Gemoets,
• Stefano Bonciolini and
• Koen Van Aken

Beilstein J. Org. Chem. 2023, 19, 1146–1154, doi:10.3762/bjoc.19.82

• oxygen- or radical-sensitive functionalities (i.e., an amino (2w) or nitro group (2x)). On the other hand, oxidizable groups, such as alcohols (2e), and halogens, such as such as chloro and fluoro on the aromatic ring (2i ,2j, 2k), were well tolerated. However, the presence of a iodo group (2v

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

• Elena Y. Mendogralo and
• Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

• yields than with substrate 4d containing a strong electron-withdrawing group. The product 4n with the nitro group in the para-position of starting benzaldehyde 2n was formed in only trace amounts. A similar result was also observed in the case of isonicotinaldehyde (2m). These results were associated

• with an insufficient stabilization of the generated iminium cation due to the presence of a strong electron-withdrawing nitro group (for 3n), and due to the fact that the electron deficiency of the pyridine ring is strongly manifested in an acidic media (for 3m). In addition, the disadvantages of the

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• , Burkholderia thailandensis produces malleobactins (Figure 1), which possess nitro, nitroso, and azoxy groups [6]. Although the malleobactins are weaker iron chelators than related siderophores featuring hydroxamate groups [7], recent evidence suggests that their structural peculiarities might be of relevance

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO₂F₂)

• Xian-Lin Chen and
• Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

• ). Furthermore, the desired products were not even obtained when the starting materials were connected to extra strong electron-withdrawing groups (such as a nitro group) on their aromatic rings. In addition, a series of cyclobutanone oxime derivatives were also smoothly transformed into the corresponding

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• -dicarbonyl compounds are treated with (diacetoxyiodo)benzene and tetrabutylammonium iodide, iodination occurs at the α-position of the nitro group, and the subsequent O-attack of the enol moiety leads to 2,3-dihydrofuran. Cyclopropane was successfully synthesized through C-attack as the acyl group became

• through an intramolecular aza-Wittig reaction, yielding cyclopropane-fused 2-quinolones [2]. A nitro group not only activates substrates and stabilizes the α-anion as an electron-withdrawing group but also acts as a nucleophile, electrophile, and leaving group, exhibiting diverse reactivities [3]. For

• compounds to give diarylated (oxoalkyl)malonates [6]. In the reaction using tin(II) chloride as the Lewis acid, the ring opening and nucleophilic attack of the nitro group occur, to produce functionalized isoxazolines (reaction d) [7]. In contrast, denitration under basic conditions generates highly