Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• obtain α-acylaminoamides. Innovation in recent years with alternative reagents, like N-hydroxyimides or nitric acid in place of an acid, N-alkylated hydrazines, or nitrobenzene derivatives (reduced in situ to anilines) instead of amines, and in situ-prepared isocyanides, makes it a versatile method for

Homogeneous continuous flow nitration of O-methylisouronium sulfate and its optimization by kinetic modeling

• Jiapeng Guo,
• Weike Su and
• An Su

Beilstein J. Org. Chem. 2024, 20, 2408–2420, doi:10.3762/bjoc.20.205

• effective and non-toxic neonicotinoid insecticides, such as dinotefuran and clothianidin [2][3][4]. Currently, the industrial production of O-methyl-N-nitroisourea usually involves the nitration of O-methylisouronium sulfate (IO) with a mixture of sulfuric acid (H2SO4) and nitric acid (HNO3) in a batch

• reaction were investigated as well as the apparent and intrinsic rate constants based on nitric acid and NO2+ observations were obtained, respectively. The apparent rate constants observed based on nitric acid are highly correlated with the mass fraction of sulfuric acid, increasing and then decreasing as

• serve as guidance for industrial production. Experimental Materials and methods Chemicals O-Methylisouronium sulfate (IO, 95%) was purchased from Shanghai Yien Chemical Technology Co., Ltd; fuming nitric acid (HNO3, 98.0%) was purchased from Sinopharm Chemical Reagent Co., Ltd.; sulfuric acid (H2SO4

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

• 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

A new route for the synthesis of 1-deazaguanine and 1-deazahypoxanthine

• Raphael Bereiter,
• Marco Oberlechner and
• Ronald Micura

Beilstein J. Org. Chem. 2022, 18, 1617–1624, doi:10.3762/bjoc.18.172

• differed from the above path by leaving the hydroxy group of all intermediate 4-hydroxypyridine derivatives 12–15 unprotected [19]. Moreover, instead of azo coupling or nitroso formation, a simple nitration protocol with nitric acid to give the nitro derivative 13 and subsequent reduction with Raney nickel

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• safe two-step synthesis of 56 from cyclohexanone. In the first step, a solution of cyclohexanone in dodecane is mixed in a Q-piece with hydrogen peroxide, nitric acid, and formic acid and subsequently pumped at room temperature through a PTFE tube reactor with a residence time of 93 min. The resulting

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• -4-sulfonic acid (15) by oxidation with nitric acid in an aqueous medium (Scheme 1A). In 1894, Böniger developed [44] the first reaction of β-NQS with phenylamines. He synthesized β-NQS using a modified method developed by Witt, which quickly reacted with different amines to form colored products

• transformed into α-nitroso-β-naphthol (17); then, in a single step, a sulfonic group was added, and the nitrous group was reduced, forming compound 15, which was transformed into β-NQSNa (18) after oxidation with nitric acid. Despite not knowing exactly the structure of the adduct, Folin speculated that the

Breaking paracyclophane: the unexpected formation of non-symmetric disubstituted nitro[2.2]metaparacyclophanes

• Suraj Patel,
• Tyson N. Dais,
• Paul G. Plieger and
• Gareth J. Rowlands

Beilstein J. Org. Chem. 2021, 17, 1518–1526, doi:10.3762/bjoc.17.109

• . Reaction of 1 with nitric acid alone led to a surprisingly clean, nitration, albeit by a very slow reaction. As stated earlier, nitration is normally a messy reaction. Presumably, the low concentration of nitronium ion present in equilibrium with the acid promotes a clean reaction without polymerization or

• highly oxidizing conditions, dehydrogenation of the resulting cyclohexadienol would give 11.The electron-rich 4-hydroxy[2.2]metaparacyclophane (9) participates in ortho selective nitration to give 5. Nitric acid has previously been used to oxidize phenols to cyclohexadienones [69][70], and a plausible

Cascade intramolecular Prins/Friedel–Crafts cyclization for the synthesis of 4-aryltetralin-2-ols and 5-aryltetrahydro-5H-benzo[7]annulen-7-ols

• Jie Zheng,
• Shuyu Meng and
• Quanrui Wang

Beilstein J. Org. Chem. 2021, 17, 1481–1489, doi:10.3762/bjoc.17.104

• -vinylnaphthalen-2-yl)acetaldehyde (13h) was prepared from 1-bromo-2-naphthaldehyde in 48% yield over the three steps. It should be noted that the nitro-substituted intermediate 11d was prepared by nitration of 11a with nitric acid under the promotion of acetic anhydride. With the accessibility of the aromatic

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• community has always been apt to try and replicate, or sometimes improve upon the initial resource. One of the first recorded preparations of a synthetic aroma chemical was the reaction of oil of amber with fuming nitric acid, which gave a musky odour as described by scientists at the Berlin Academy in 1759

Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues

• Rashmi Singh,
• Tomas Horsten,
• Rashmi Prakash,
• Swapan Dey and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 977–982, doi:10.3762/bjoc.17.79

• expand the library of derivatives containing core structure 13, electrophilic aromatic substitution of this compound was explored (Scheme 2). Nitration of 13 using 70% nitric acid in glacial acetic acid gave the corresponding regioisomers 14 and 15 in 53% and 41% isolated yield, respectively. The 1H NMR

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• protonated and therefore better water-soluble would allow immobilizing it together with (R)-1. As acid, we initially used diluted nitric acid because the eventual formation of the zinc complexes with zinc(II) nitrate would anyway lead to AuNPs containing nitrate anions. Adding the acid to the NPcit solution

• prior to the addition of the ligand mixture caused the AuNPs to precipitate, likely because the protecting citrate molecules were protonated. Therefore, the reaction mixture was adjusted to pH 3 with 0.1 mol/L nitric acid shortly after adding the solution containing the ligands in methanol. A color

• the unsatisfactory reproducibility of this strategy was likely that the exact moment at which nitric acid was added had a strong effect on the extent to which 2 reacted with NPcit, and ensuring that the acid was always added at exactly the same moment was difficult. We therefore considered the use of

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• the surface of the treated carbons in form of carboxyl groups, ketones, ether groups and carboxyl-carbonate structures is higher using nitric acid compared to hydrogen peroxide [116]. Nitrogen adsorption–desorption isotherms: The surface area and pore size distribution of solid catalyst materials can

• -containing surface groups on the activated carbon materials. They could observe that gas phase oxidation led to a higher amount of mainly hydroxy and carbonyl groups, whereas liquid phase treatment with nitric acid results in an increase of carboxylic acid groups [110]. Lillo-Ródenas et al. used TPD for the

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• tetrapropoxycalix[4]arene 8, which used a combination of nitric acid and acetic acid, proved inconsistent in our hands (see Supporting Information File 1 for more details). We therefore conducted a careful study to optimize the reaction using a more traditional combination of nitric acid and sulfuric acid (Table 1

• ). A solution of tetrapropoxycalix[4]arene 8 in DCM was stirred at 0 °C and treated with nitric acid (70%) and concentrated sulfuric acid; after 300 min the solution had reached 18 °C, at which point the reaction was diluted with water and extracted into methylene chloride. Purification via silica gel

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• two steps including the treatment of 238 with concentrated nitric acid in glacial acetic acid, followed by the reaction of 10% aqueous alkali at room temperature (Scheme 40) [157]. 5.2. 6-Hydroxy-2,3-benzotropone (239) 5.2.1. Synthesis of 6-hydroxy-2,3-benzotropone (239): Takahashi and co-workers

• ) [174]. Catalytic hydrogenation of 241 over Adams's catalyst (PtO2.H2) gave the diol 295 (Scheme 49) [162][165][174]. Treatment of 241 with alkaline hydrogen peroxide caused degradative fission to give o-carboxycinnamic acid (296) [165], while nitration of 241 with nitric acid in an acetic acid solution

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• nitric acid increased the yield to 56% with trace amount of starting material 23a recovered. Finally, the effect of organic protic acids was investigated (Table 1, entries 7–9) which produced ring-opened product 26 in low to moderate yields. The use of p-toluenesulfonic acid monohydrate produced the ring

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• understand and model these biological pathways, oxidative aromatization of 1,4-DHP to their corresponding pyridine derivatives has acclaimed wide attention. A variety of oxidants such as urea nitrate, BrCCl3/hν, nitric acid, nitric oxide, N-methyl-N-nitroso-p-toluenesulfonamide, DDQ etc. has been used to

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• many cases 3,6-unsubstituted carbazoles have been nitrated by using fuming or 70% nitric acid with or without addition of acetic anhydride [46]. Two inorganic nitrates, such as copper(II) nitrate [47] or cerium(IV) ammonium nitrate (CAN) [48] have also been used to give 3-mononitro or 3,6-dinitro

• carbazoles as major products. Taking into account the above mentioned procedures, we have used fuming nitric acid and acetyl nitrate [49] (generated in situ from fuming nitric acid and acetic anhydride) for nitration of indolo[3,2-b]carbazole 1a as a model compound (Scheme 1, Table 1). These experiments have

• desired product in 88% yield. At the same time, in the experiment with fuming nitric acid (5 equiv), used instead of acetyl nitrate (Table 1, entry 5), we have obtained a mixture of compound 2a and byproducts again. The molecular structure of compound 2a has been proved unequivocally by X-ray

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• nitric acid and acetic acid gave dinitro compound 6. The nitro groups in 6 were then reduced by treatment with iron powder and acetic acid. The cyclization of the diamino compound 7 (as described for compound 1) afforded the difluorinated benzothiadiazole 8. The monomer M2 was obtained by coupling 8 with

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• °C. 15 mL of nitric acid (65%) were added dropwise (~10 min) at 60 °C upon vigorous stirring. After the addition was completed, the resulting mixture was further stirred at 60 °C. The reaction was monitored by TLC (solvent EtOAc–n-heptane 1:9). After appearance of the spot of the dinitro product

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• nitrates underwent rapid pseudohydrolysis; a process that generates corrosive nitric acid and non-volatile SOA [13]. Similar to the isoprene studies by Pye et al. the role of organic nitrates derived from terpenes is starting to gain traction. Rindelaub et al. undertook a photochemical reaction chamber

• , rac-12 and (E)-4. A comprehensive survey of the literature revealed three general synthesis routes to IPNs. In summary, Shepson et al. [17] reacted isoprene epoxide with concentrated nitric acid (Scheme 2, path A); Kames et al. outlined the O-nitration of simple alcohols using dinitrogen pentoxide [18

• ] (Scheme 2, path B); Cohen et al. reported the application of bismuth(III) nitrate for isoprene epoxide ring-opening/trapping with nitrate [19] (Scheme 2, path C). The 2010 report by Shepson et al. (path A) exploited chemistry originally described by Nichols et al. who, employing nitric acid as a

New metathesis catalyst bearing chromanyl moieties at the N-heterocyclic carbene ligand

• Agnieszka Hryniewicka,
• Szymon Suchodolski,
• Agnieszka Wojtkielewicz,
• Jacek W. Morzycki and
• Stanisław Witkowski

Beilstein J. Org. Chem. 2015, 11, 2795–2804, doi:10.3762/bjoc.11.300

• -enol [27]. Chromane 10 was nitrated with fuming nitric acid to give 6-nitrochromane 11 in 58% yield according to Mahdavian [28] (Scheme 1). Nitration using the Smith procedure [29] led to the expected nitrochromane 11, however, formation of an admixture of 5a,6-dinitrochromane was observed. Reduction

• ) To the solution of 2,2,5,7,8-pentamethylchromane (10) (2.5 g, 0.012 mol) in dry CH2Cl2 (150 mL) cooled to 0 °C fuming nitric acid (1.5 mL, 3 equiv, 0.036 mol) was added in one portion. The reaction was carried out at 0 °C for 1.5 h. Next the reaction mixture was washed with saturated NaHCO3, dried

Syntheses of 2-substituted 1-amino-4-bromoanthraquinones (bromaminic acid analogues) – precursors for dyes and drugs

• Enas M. Malik,
• Younis Baqi and
• Christa E. Müller

Beilstein J. Org. Chem. 2015, 11, 2326–2333, doi:10.3762/bjoc.11.253

• introduce a carboxylate group by oxidizing 2-methylanthraquinone using nitric acid in the presence of nitrobenzene and heating the reaction mixture to 200 °C [54], a procedure which failed in our hands. However, introduction of a bromine or a hydroxymethyl residue in position 2 of 1-aminoanthraquinone was

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

• Yuri A. Rulev,
• Zalina Gugkaeva,
• Victor I. Maleev,
• Michael North and
• Yuri N. Belokon

Beilstein J. Org. Chem. 2015, 11, 1614–1623, doi:10.3762/bjoc.11.176

• , 9H). 3-(tert-Butyl)-2-hydroxy-5-nitrobenzaldehyde (5) Prepared by a modified literature procedure [25]. To a stirred solution of 3-(tert-butyl)-2-hydroxybenzaldehyde (1.0 g, 4.5 mmol) in glacial acetic acid (20 mL) was added 3.3 M nitric acid (4.0 mL). The solution was heated to reflux for 30 minutes

Quarternization of 3-azido-1-propyne oligomers obtained by copper(I)-catalyzed azide–alkyne cycloaddition polymerization

• Shun Nakano,
• Akihito Hashidzume and
• Takahiro Sato

Beilstein J. Org. Chem. 2015, 11, 1037–1042, doi:10.3762/bjoc.11.116

• inorganic compounds although it was not possible to remove completely inorganic compounds from oligoAP even after washing repeatedly with a saturated aqueous solution of ethylenediaminetetraacetic acid (EDTA) and 5% nitric acid [37]. These observations indicate that quarternization weakens the interaction

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13