From amines to (form)amides: a simple and successful mechanochemical approach

• Federico Casti,
• Rita Mocci and
• Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 1210–1216, doi:10.3762/bjoc.18.126

• using secondary aliphatic amines such as dibenzyl- and methylbenzylamine, which provided amides 16 and 17 in 87% and 74% isolated yields, respectively. Furthermore, the methodology allowed us to synthesize a set of aromatic formanilides (amides 18–20, Scheme 2). Indeed, the deactivated p-nitroaniline

Green synthesis of C5–C6-unsubstituted 1,4-DHP scaffolds using an efficient Ni–chitosan nanocatalyst under ultrasonic conditions

• Soumyadip Basu,
• Sauvik Chatterjee,
• Suman Ray,
• Suvendu Maity,
• Prasanta Ghosh,
• Asim Bhaumik and
• Chhanda Mukhopadhyay

Beilstein J. Org. Chem. 2022, 18, 133–142, doi:10.3762/bjoc.18.14

• -dichloroaniline (98% extra pure), p-nitroaniline (98.5% extra pure), m-nitroaniline (99% extra pure), and n-butylamine (98% purity) were bought from Loba Chemie. Benzylamine (99% purity) and p-methoxybenzylamine (98% purity) were bought from Sigma-Aldrich. The reactions were performed under sonication in a

Copper-promoted/copper-catalyzed trifluoromethylselenolation reactions

• Clément Ghiazza and
• Anis Tlili

Beilstein J. Org. Chem. 2020, 16, 305–316, doi:10.3762/bjoc.16.30

• demonstrated the feasibility of the reaction by starting directly with p-nitroaniline. Moreover, the authors demonstrated that the reaction could easily be scaled up to a 7 mmol scale, and the desired product was obtained in a comparable yield of 70%, and 73% starting from the corresponding aryldiazonium salt

Polyaminoazide mixtures for the synthesis of pH-responsive calixarene nanosponges

• Antonella Di Vincenzo,
• Antonio Palumbo Piccionello,
• Alberto Spinella,
• Delia Chillura Martino,
• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2019, 15, 633–641, doi:10.3762/bjoc.15.59

• -triazol-1-yl)alkylidene chains as the linkers between the calixarene monomer units. Even these materials were proven effective in sequestrating organic model pollutants, such as p-nitroaniline derivatives or dyes, from aqueous solution. However, their synthesis required much longer times in comparison

• presence of unreacted alkyne groups. Sequestration abilities of the CaNS nanosponges The possible pH-responsive sequestration abilities of materials CaNS-I and CaNS-II were verified by means of sequestration tests on a set of suitable guest, namely p-nitroaniline derivatives 6–10 and dyes 11–15 (Figure 4

• relevant nanosponges CaNS-I and CaNS-II were similarly subjected to spectroscopic characterization (FTIR, solid-state CP-MAS NMR), whereas their pH-dependent absorption abilities were verified towards typical probe guests such as p-nitroaniline derivatives and commercial dyes. Our results indicate an

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• of CaNSs in sequestering organic species from buffered aqueous solutions were verified, using model p-nitroaniline derivatives 1–5 and dyes 6–10 as the guests. The sequestration abilities of CaNSs were estimated (see Experimental) by equilibrating a given amount of material with a fixed volume of a

• , indeed, possible dependence on pH might arise from the presence of the weakly basic 1,2,3-triazole rings of the linker units, which can supply an overall positive charge density to the polymer lattice upon protonation. A first set of experiments was devoted to p-nitroaniline derivatives 1–5. These

• varied though maintaining a fixed chromophore moiety. The results obtained, expressed in terms of percent of guest absorbed, are summarized in Table 1. As we can notice, the parent p-nitroaniline (1) is absorbed fairly well by CaNSs under neutral conditions, up to an extent comparable with the one

Binding abilities of polyaminocyclodextrins: polarimetric investigations and biological assays

• Marco Russo,
• Daniele La Corte,
• Annalisa Pisciotta,
• Serena Riela,
• Rosa Alduina and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2751–2763, doi:10.3762/bjoc.13.271

• applications in biological systems, such as vectors for simultaneous drug and gene cellular uptake or alternatively for the protection of macromolecules. In particular, we exploited polarimetry to test their interaction with some model p-nitroaniline derivatives, chosen as probe guests. The data obtained

• (Figure 1a), obtained in a previous work [37], with a set of selected neutral and anionic model p-nitroaniline derivatives 1–4 (Figure 1b) at different pH values. The materials chosen differ for the length and number of N atoms of the polyamine chains, and for the different average number of pendants per

• protonation step at each polyamine branch occurs. This suggests the presence of strong intrachain interactions before protonation. Binding abilities of AmCDs towards p-nitroaniline derivatives 1–4 p-Nitroanilines constitute a good class of probe molecules for testing the microscopic behaviour of cyclodextrins

Binding abilities of a chiral calix[4]resorcinarene: a polarimetric investigation on a complex case of study

• Marco Russo and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2017, 13, 2698–2709, doi:10.3762/bjoc.13.268

• . Moreover, some p-nitroaniline derivatives were selected, because this class of molecules have been already proven as excellent probe guests to assess the microscopic interactions controlling the binding abilities of cyclodextrins [43][44][45][49][50][51][52][53]. Results and Discussion Synthesis and

• with p-nitroaniline derivatives by means of NMR techniques. In particular, the 1H spectrum of the 8·CAP−1 1:1 complex (Figure 6) shows a large upfield shift (and loss of resolution) of the signals relevant to the aromatic H atoms of the guest (the signals relevant to the aliphatic moiety are deeply

• observed of purely aliphatic cations; ii) non-specific electrostatic interactions, as accounted for by the lack of inclusion of anions. Furthermore, at least in the case of the p-nitroaniline derivatives, the aliphatic moiety of the guest interacts with the prolinylmethyl groups at the host rim, affecting

The in situ generation and reactive quench of diazonium compounds in the synthesis of azo compounds in microreactors

• Faith M. Akwi and
• Paul Watts

Beilstein J. Org. Chem. 2016, 12, 1987–2004, doi:10.3762/bjoc.12.186

• systems. It involves the diazotization of p-nitroaniline 2 to form 20 which is subsequently coupled to 21. Diphenylamine (21), the coupler used in this reaction is sparingly soluble in aqueous media thus rendering it quite difficult to use in this synthesis and as such, methanol was used as the azo

• temperature of 25 °C, excellent conversions were attained in the azo coupling reaction of the diazonium salt solution of 2,4-dimethylaniline to 2-naphthol whereas the azo coupling reaction of the diazonium salt solution of p-nitroaniline to diphenylamine was found to thrive at a pH of 5.71 and at a

• distilled water. Similarly, the reactant solutions A and B (diazotized primary aromatic amine and coupler) in the azo coupling of diazonium salt solution of p-nitroaniline to diphenylamine were prepared as follows: Solution A (diazotized primary aromatic amine): p-nitroaniline (0.2918 g) was dissolved in

Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

• Martin Popr,
• Sergey K. Filippov,
• Nikolai Matushkin,
• Juraj Dian and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2015, 11, 192–199, doi:10.3762/bjoc.11.20

• PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid

• guest molecules (salicylic acid – SAL, p-methoxyphenol – MEQ, p-nitroaniline – NIA) at three different pH values (2.50, 7.00, 10.00) (Scheme 2). The Ks values were obtained by isothermal titration microcalorimetry (ITC) [32][33], which was selected as the most suitable method for our purpose. Other

Synthesis of functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones] via one-pot four-component reactions

• Li-Juan Zhang,
• Qun Wu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 846–851, doi:10.3762/bjoc.9.97

• spiro[indoline-3,4’-pyridines] 2a–2h as the main products (Table 2, entries 1–8). Due to fact that m-nitroaniline and p-nitroaniline could not react with methyl propiolate to give the desired intermediate β-enamino ester, they were not utilized in this reaction. On the other hand p-methoxyaniline, p

A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates

• Xinghua Wu,
• Yu Chen,
• Herve Aloysius and
• Longqin Hu

Beilstein J. Org. Chem. 2011, 7, 1030–1035, doi:10.3762/bjoc.7.117

• -amino-4-methylcoumarin; p-nitroaniline; proteolytic substrate; selenocarboxylate/azide amidation; synthon; Introduction Chromogenic and fluorogenic amino acid/peptide conjugates are widely used as substrates in enzyme assays for protease activity and specificity [1]. Proteolytic cleavage of the amino

• acid/peptide conjugates liberates the free chromophore or fluorophore, allowing the convenient determination of the rate of enzyme catalysis with a UV or fluorescence spectrophotometer. p-Nitroaniline (pNA) is one of the most commonly used chromogenic reagents. The synthesis of peptide-pNAs usually

• involves formation of aminoacyl-pNAs through the attachment of P1 amino acid to the amino group of p-nitroaniline, followed by fragment condensation or stepwise elongation [P1 amino acid refers to the residue immediately amino terminal to the scissile bond in a proteinase substrate]. However, the synthesis

Hybrid biofunctional nanostructures as stimuli-responsive catalytic systems

• Gernot U. Marten,
• Thorsten Gelbrich and
• Annette M. Schmidt

Beilstein J. Org. Chem. 2010, 6, 922–931, doi:10.3762/bjoc.6.98

• investigated by the classical BAPNA method [57] and is compared to the native protein. Trypsin-catalyzed hydrolysis of benzoyl-Arg p-nitroanilide (BAPNA) results in the formation of p-nitroaniline that can be quantified by UV–vis spectroscopy at 410 nm (Scheme 2) [58]. The increase of relative absorption A410

• is observed over time for different substrate concentrations cBAPNA. A410 is directly correlated to the p-nitroaniline concentration, thus the reaction rate v = d[P]/dt can be obtained from the initial slopes [2]. As a control experiment the primarily FeOx@P(O8M´84S8) nanoparticle dispersion without