Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• be used to analyze the content of samples withdrawn at suitable intervals. That is why many research groups prefer to use a simpler model, 2-hydroxypropyl p-nitrophenyl phosphate (HPNP; 1, Figure 5), the hydrolysis of which can be followed by UV-spectrophotometry. A lot of useful observations have

• attacking 2´-O−, the KIE is inverted, 16knuc/18knuc = 0.984 ± 0.004 [54]. Both effects are large and consistent with advanced P–O5´ fission and P–O2´ formation in the transition state. For comparison, with uridine 3´-(p-nitrophenyl phosphate), the leaving group KIE expectedly is small, 16klg/18klg = 1.0059

Carbohydrate inhibitors of cholera toxin

• Vajinder Kumar and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34

• for the terminal galactose part of GM1 [37][38][39]. They screened a number of galactose derivatives with substitution at O1 and C2 and found that the most potent molecule in this library was m-nitrophenyl α-D-galactoside (4) which was 100 times better than galactose for binding to CTB [38][39]. In

• another report, Mitchell et al. designed and synthesised twenty 3,5-substituted phenylgalactosides, e.g., 5 and when these compounds were tested on CT it was found that they have a six-fold higher affinity than m-nitrophenyl α-D-galactopyranoside (Figure 4) [40]. Vrasidas et al. synthesised a simple

• exhibit binding affinity one order higher than m-nitrophenyl galactopyranoside (4) [48]. In another recent report, low molecular weight poly(N-acryloylmorpholine) was used to link galactose residues to form a bivalent inhibitor, but the biological assay demonstrated only moderate inhibitory activity [49

Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing

• Françoise Debart,
• Christelle Dupouy and
• Jean-Jacques Vasseur

Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32

• , protected at O6 and O4 with a 2-(2-nitrophenyl)propyl (NPP) group, into siRNA (Scheme 20A) [81]. The most efficient siRNAs targeting EFGP expression in transfected HeLa cells were those modified in the central part of the siRNA – that is, in the nucleobases neighboring the argonaute cleavage site of mRNA

One-pot sequential synthesis of tetrasubstituted thiophenes via sulfur ylide-like intermediates

• Jun Ki Kim,
• Hwan Jung Lim,
• Kyung Chae Jeong and
• Seong Jun Park

Beilstein J. Org. Chem. 2018, 14, 243–252, doi:10.3762/bjoc.14.16

• compounds 7f and 7g, the low reactivity resulted from the decreased mesomeric effect of the furan structure: the higher electronegativity of oxygen facilitated the polarized form [71]. Among various arenes, the 4-nitrophenyl substituent 7p only afforded the desired thiophene 8p in a moderated yield (42

Transition-metal-free [3 + 3] annulation of indol-2-ylmethyl carbanions to nitroarenes. A novel synthesis of indolo[3,2-b]quinolines (quindolines)

• Michał Nowacki and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2018, 14, 194–202, doi:10.3762/bjoc.14.14

• ]. Several methods use prerequisite quinoline derivatives for the construction of the pyrrole ring of quindoline. 2-(2-Aminophenyl)-3-bromoquinoline cyclized to quindoline by reacting with pyridinium hydrochloride (d) [14]. Insertion of nitrene generated from 2-(2-nitrophenyl)quinoline by triethylphosphite

Synthesis and spectroscopic properties of β-meso directly linked porphyrin–corrole hybrid compounds

• Baris Temelli and
• Hilal Kalkan

Beilstein J. Org. Chem. 2018, 14, 187–193, doi:10.3762/bjoc.14.13

• with aldehydes [42]. When electron-withdrawing 4-nitrophenyl and pentafluorophenyl substituents were used on the dipyrromethane, hybrid compounds 4c and 4e were isolated in 16% and 20% yields, respectively. The synthesis of 4e with InCl3 afforded a very low yield, thus an equimolar amount of AlCl3 was

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

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

• slight excess (ca. 10%) of the proper amine in DMSO at 70 °C for 4 hours in the presence of Na2CO3 (1 equiv). The same procedure was adapted for the synthesis of guest 4. N-(4-Nitrophenyl)iminodiacetic acid disodium salt (4) Iminodiacetic acid (1.33 g, 10 mmol) was treated with an equimolar amount of

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

• buried under those of the host, and cannot be identified). This indicates that the p-nitrophenyl group is allocated in the deshielding region provided by the aryl subunits of the host. Therefore, we can conclude that the aromatic moiety of the guest is specifically included into the cavity, in a quite

• macrocycle cavity. Consequently, the inclusion of the guest forces them in a conformation that is more exposed to the solvent bulk. Finally, taking back to the guest, the inclusion of its p-nitrophenyl group into the cavity implies that the aliphatic moiety protrudes out of the proline-decorated host rim

• subunit. The case of the imidazolium derivative 12 is intriguing, because in principle its 1:1 complex might involve the inclusion of either aromatic ring. However, the preferential inclusion of the p-nitrophenyl group may be reasonably presumed on the grounds of the fact that the complex formed by the

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

• Alena A. Vavilova and
• Ivan I. Stoikov

Beilstein J. Org. Chem. 2017, 13, 1940–1949, doi:10.3762/bjoc.13.188

• Alena A. Vavilova Ivan I. Stoikov Kazan Federal University, Kremlevskaya, 18, Kazan 420008, Russian Federation 10.3762/bjoc.13.188 Abstract New p-tert-butylthiacalix[4]arenes, which are mono-, 1,2-di- and tetrasubstituted at the lower rim containing N-(4’-nitrophenyl)acetamide and N,N

• receptors for F−, CH3CO2− and H2PO4− ions, which based on the synthesized thiacalix[4]arenes, have been obtained. It was shown that p-tert-butylthiacalix[4]arene tetrasubstituted at the lower rim by N-(4’-nitrophenyl)acetamide moieties bonded to the anions studied with association constants within the range

• receptor. In contrast to the 1,3-disubstituted macrocycle containing two N-(4’-nitrophenyl)acetamide moieties, the 1,2-disubstituted thiacalix[4]arene, which contains only one such fragment and a N,N-diethylacetamide moiety, selectively binds F− anions. Keywords: anion binding; synthesis; thiacalixarenes

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• in 1:1 ratios – were always formed, which is a serious drawback of this approach. Another well-known method based on retrosynthetic disconnections at the same C–C bond employed intramolecular vicarious nucleophilic substitution of hydrogen in the substituted N-(3-nitrophenyl)chloromethylsulfonamides

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• milling was performed at low temperatures (−30 °C) using an in-house ball mill equipped with a cooling jacket. As isothiocyanate component, liquid phenyl isothiocyanate and solid methyl, 1-naphthyl, 4-bromophenyl and 4-nitrophenyl isothiocyanates were screened. While ammonia, methylamine and dimethylamine

• next screened as catalysts in Morita–Baylis–Hillman reaction, and their performance matched the previously published catalytic activity. An analogous click-type reaction between 4-nitrophenyl isothiocyanate and trans-1,2-diaminocyclohexane quantitatively afforded enantiomeric (1R,2R)-10 and (1S,2S)-10

• one or two equivalents of phenyl, 4-methoxyphenyl, 4-chlorophenyl or 4-nitrophenyl isothiocyanate. In the 1:1 reaction, solvent-free mechanosynthesis selectively provided stable mono-thioureas 19a–d in ≥95% after 30 minutes (Scheme 6a). When the reactants were milled in a 1:2 ratio for 3 hours (9

Switchable highly regioselective synthesis of 3,4-dihydroquinoxalin-2(1H)ones from o-phenylenediamines and aroylpyruvates

• Juraj Dobiaš,
• Marek Ondruš,
• Gabriela Addová and
• Andrej Boháč

Beilstein J. Org. Chem. 2017, 13, 1350–1360, doi:10.3762/bjoc.13.132

• substituted o-phenylenediamine 11. Sakata et al. reported an interesting one-pot procedure yielding 6-substituted SYN quinoxalin-2(1H)-ones from substituted N-(2-nitrophenyl)-3-oxobutanamides [28]. Another example for preparation of the desired regioisomer starts from the nucleophilic substitution of o

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• , 55.4, 51.6; IR (ATR): 2951, 2257, 1719, 1605, 1543, 1515, 1458, 1438, 1416, 1361, 1334, 1265, 1246, 1179, 1168, 1100, 1069, 1027, 948, 830, 735, 598, 583; HRMS: [M + H]+ calcd for C14H11NO2, 256.09682; found, 256.09730. Methyl 1-[(4-nitrophenyl)ethynyl]-1H-pyrrole-2-carboxylate (7b). To a solution of 1

• , 2920, 1670, 1605, 1510, 1473, 1373, 1341, 1242, 1176, 1021, 965, 830, 800, 736, 634, 595; HRMS: [M + H]+ calcd for C13H8INO2, 256.10805; found, 256.10860. 4-(4-Nitrobenzyl)pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one (13b). Methyl 1-[(4-nitrophenyl)ethynyl]-1H-pyrrole-2-carboxylate (7b, 0.30 g, 1.46 mmol) in

• , 1371, 1332, 1089, 1055, 766, 729, 696, 685; HRMS: [M + H]+ calcd for C13H8INO2, 337.96791; found, 337.97070. 4-Iodo-3-(4-nitrophenyl)-1H-pyrrolo[2,1-c][1,4]oxazin-1-one (19b). To a solution of methyl 1-[(4-nitrophenyl)ethynyl]-1H-pyrrole-2-carboxylate (7b, 0.108 g, 0.400 mmol) in DCM (20 mL), I2 (0.101

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

• contrast, the δ(C-5) values vary strongly with the substituent attached to this carbon atom. Whereas the values for 7a–c reflect the different interaction of the phenyl, 3,4,5-trimethoxyphenyl and 4-nitrophenyl substituents with the positive charge density at C-5 through mesomeric and inductive effects

• maximum in the series R = CH3 < phenyl ≈ 3,4,5-trimethoxyphenyl < 4-nitrophenyl. For 7a–c, this absorption band could result from a charge transfer between the amidinate moiety, representing the HOMO of the mesoionic system, and an unoccupied π-orbital of the C(=O)Ar group. Upon N-protonation or N

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

• Patrick T. Campos,
• Leticia V. Rodrigues,
• Andrei L. Belladona,
• Caroline R. Bender,
• Juliana S. Bitencurt,
• Fernanda A. Rosa,
• Davi F. Back,
• Helio G. Bonacorso,
• Nilo Zanatta,
• Clarissa P. Frizzo and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

• , thiophene-2-glyoxylic acid, and N-(2-amino-4-nitrophenyl)acetamide, in accordance with the mechanism proposed in this work. To rationalize why the cyclization reaction between the amidines 8g,h and the α-ketoester did not occur, the HOMO coefficient and charge densities for the nitrogens of the amidine were

Chemical probes for competitive profiling of the quorum sensing signal synthase PqsD of Pseudomonas aeruginosa

• Michaela Prothiwa,
• Dávid Szamosvári,
• Sandra Glasmacher and
• Thomas Böttcher

Beilstein J. Org. Chem. 2016, 12, 2784–2792, doi:10.3762/bjoc.12.277

• modelling and chemical lead optimization. Examples of successful inhibitors are represented by the scaffolds of various 2-benzamidobenzoic acids [11][25][26], 2-nitrophenyl derivatives [27][28][29], ureidothiophene-2-carboxylic acids [24][30], and catechol-based compounds [31]. Many promising in vitro

Thiazol-4-one derivatives from the reaction of monosubstituted thioureas with maleimides: structures and factors determining the selectivity and tautomeric equilibrium in solution

• Alena S. Pankova,
• Pavel R. Golubev,
• Alexander F. Khlebnikov,
• Alexander Yu. Ivanov and
• Mikhail A. Kuznetsov

Beilstein J. Org. Chem. 2016, 12, 2563–2569, doi:10.3762/bjoc.12.251

• it had been done earlier for 3a. On the other hand, heating the solution of thiazolidine 3g up to 120 °C led to coalescence. At this temperature even the signals of the ortho-protons of the 4-nitrophenyl ring (Δδ = 0.9 ppm at −20 °C) coalesced into one (Figure 2). The deviation of the tautomeric

• ratio for 3g from the ones observed for thiazolidines 3a–f seems to be caused by a weakening of the conjugation in the fragment NH–C=N–C=O realized in A form due to the strong electron-withdrawing effect of the 4-nitrophenyl group at the terminal NH group. Introducing an alkyl group in thioureas 1d–f

A direct method for the N-tetraalkylation of azamacrocycles

• Andrew J. Counsell,
• Angus T. Jones,
• Matthew H. Todd and
• Peter J. Rutledge

Beilstein J. Org. Chem. 2016, 12, 2457–2461, doi:10.3762/bjoc.12.239

• ), NaOH (1 M), RCH2Br (4.1 equivalents), rt, 6 h; R = C≡CH (3 and 8), C6H5 (4 and 9), o-bromophenyl (5 and 10), p-nitrophenyl (6 and 11), 2-naphthyl (7 and 12, see Table 1 for yields.). Direct synthesis of N-tetraalkylated macrocycles 3–12 from cyclam (1) and cyclen (2). Supporting Information Supporting

Regiocontroled Pd-catalysed C5-arylation of 3-substituted thiophene derivatives using a bromo-substituent as blocking group

• Mariem Brahim,
• Hamed Ben Ammar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2016, 12, 2197–2203, doi:10.3762/bjoc.12.210

• -substituted thiophenes derivatives containing two different aryl groups at C2 and C5 positions via Suzuki coupling in the second step was also attempted (Scheme 8). The reaction of 5 with phenylboronic acid in the presence of only 1 mol % Pd(OAc)2 catalyst and K2CO3 as base gave 3-methyl-5-(4-nitrophenyl)-2

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• towards highly electrophilic p-nitrophenyl carbonate derivatives with ring opening of the bicyclic ring to form corresponding substituted ε-caprolactam and γ-lactam derived carbamates. This simple method presents a unified strategy to synthesize structurally diverse ε-caprolactam and γ-lactam compounds

• with a large substrate scope. Keywords: carbonates; DBN; DBU; lactams; p-nitrophenyl; Introduction Among various organic bases, amidines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) having an imino group attached to the α-carbon of the amine are

• behavior of DBU towards imidazolides providing ε-caprolactam-derived carbamates and amides [17]. Here, in this report we present the results obtained by the reaction of DBU and DBN with highly electrophilic p-nitrophenyl carbonates leading to ε-caprolactam and γ-lactam carbamates. p-Nitrophenyl carbonates

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

• experimental domain had no significant effect on the reaction response. For information, this flow rate range covers a residence time of 0.37 to 0.86 minutes. Azo coupling reaction in the synthesis of 4-(2-(4-nitrophenyl)diazenyl)-N-phenylbenzenamine in LTF-MS microreactors The synthesis of azo compounds

• involving couplers containing aminated aromatic systems is usually carried out in slightly acidic reaction conditions. The synthesis of 4-(2-(4-nitrophenyl)diazenyl)-N-phenylbenzenamine was an interesting choice for demonstrating the synthesis of azo compounds involving couplers containing aminated aromatic

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• and 4-nitrophenyl substituted derivatives. All 1,2-oxazines were isolated in high yield (>94%). An asymmetric hetero-Diels–Alder reaction used for the synthesis of (−)-epibatidine was reported by Royer [125][126]. The crucial step of the epibatidine synthesis, proceeding in 64% yield, is based on the

A convenient route to symmetrically and unsymmetrically substituted 3,5-diaryl-2,4,6-trimethylpyridines via Suzuki–Miyaura cross-coupling reaction

• Dariusz Błachut,
• Joanna Szawkało and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2016, 12, 835–845, doi:10.3762/bjoc.12.82

• %) as a co-solvent with toluene. On the other hand, the attempted coupling of compound 41 with 2-nitrophenylboronic acid and (2-chloro-6-methoxyphenyl)boronic acid failed. Despite more drastic conditions (xylene, DMF, 145 °C, 48 h, 8 mol % Pd(OAc)2/16 mol % S-Phos) any amount of 3,5-bis(2-nitrophenyl

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• organic media or ionic liquids as co-solvents [24][25][26][27]. The enzymatic transglucosylation using 4-nitrophenyl β-D-glucopyranoside as the donor and almond β-glucosidase as biocatalyst gave salidroside (2) in moderate yield [28]. Recently, we have published the enzymatic glycosylation of tyrosol (2