Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• '-N compared to the 4'-O and 3'-O interactions in DNA. The 3'-amino moieties in the structure’s backbone were found to coordinate a larger amount of water molecules, on both the backbone and at groove sites. This increased hydration, as well as the configuration of the 3'-amino group enables the

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• amino group recipient. Figure 4 shows some progress curves for this mechanism with plausible values of enzyme parameters (admittedly chosen such that the ee does decline, see below). As can be seen, for these parameters the product ee falls quite rapidly from its initial 0.95 as the reaction proceeds

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

• intermediate B generated by the addition of aldehyde to enaminone A on intramolecular cyclization furnishes the final product 24 via C. Cyclic isoindole-fused furo[1,4]diazepines 26 were obtained by dehydration of the carbonyl group on the aromatic ring on treatment with an amino group. The authors attributed

• the high nucleophilicity of the amino group in the substrate 23 to control the regioselectivity of the reaction (Scheme 9). 3 Indoles Indoles have a bicyclic structure consisting of a six-membered benzene ring fused with a five-membered nitrogen-containing pyrrole ring. Figure 3 depicts some of the

• condensation between ketone and formylquinoline. The amine and the intermediate A undergo Michael addition furnishing the keto-amine B. Further, an intramolecular cyclization with the attack of the amino group onto the carbonyl functionality with subsequent elimination of a water molecule results in the

Total synthesis of pyrrolo[2,3-c]quinoline alkaloid: trigonoine B

• Takashi Nishiyama,
• Erina Hamada,
• Daishi Ishii,
• Yuuto Kihara,
• Nanase Choshi,
• Natsumi Nakanishi,
• Mari Murakami,
• Kimiko Taninaka,
• Noriyuki Hatae and
• Tominari Choshi

Beilstein J. Org. Chem. 2021, 17, 730–736, doi:10.3762/bjoc.17.62

• be constructed through a cycloamination reaction between positions C1a and N1. The synthesis of the precursor pyrroloquinoline 9 possessing a substituted amino group at the 4-position could be achieved by the electrocyclization of pyrrol-3-ylbenzene 10 containing a carbodiimide moiety as a 2

Stereoselective syntheses of 3-aminocyclooctanetriols and halocyclooctanetriols

• Emine Salamci and
• Yunus Zozik

Beilstein J. Org. Chem. 2021, 17, 705–710, doi:10.3762/bjoc.17.59

• replacement of one of the hydroxy groups with an amino group. Many aminocyclitols and their derivatives have been found to possess antibiotic properties, such as validamycins (1) [16]. Validamycin A (1) contains two aminocyclitol units, the one is valienamine (2) and the other is validamine (3, Figure 1). One

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

• Lukáš Marek,
• Lukáš Kolman,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2021, 17, 527–539, doi:10.3762/bjoc.17.47

• we recently discovered [32][33] a new synthetic pathway involving a rearrangement of 2-aryl-5-(2-aminophenyl)-4-hydroxy-1,3-thiazoles (e.g., 8aa–ad in Scheme 2) leading to the 3-[amino(aryl)methylidene]-1,3-dihydro-2H-indol-2-ones containing an unsubstituted amino group and the oxindole nucleus. In

• )methylidene]-1,3-dihydro-2H-indol-2-ones.a The prepared 3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones 5aa–ed with a primary amino group (R3 and R4: H). The prepared (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones 6aa–ef with a secondary amino group (R2 and R3: H). The prepared (Z)-3

• -[dimethylamino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones 7aa–ca with a tertiary amino group (R3 and R4: CH3). The prepared (Z)-3-[1-aminoethylidene]-1,3-dihydro-2H-indol-2-ones 10a–c. The yields of the synthesized 3-bromooxindoles 1a–e.a Supporting Information Supporting Information File 82: Synthetic

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• salts by alkali. The mesoionic compounds show a higher reactivity of the exocyclic N-atom in comparison with the 5-aminotetrazole ones that can be explained by a unique mesoionic system of the tetrazolium-5-aminides which leads up to a 5-amino-group activation. The compounds react with 1,2-dibromoethane

Supramolecular polymers with reversed viscosity/temperature profile for application in motor oils

• Jan-Erik Ostwaldt,
• Christoph Hirschhäuser,
• Stefan K. Maier,
• Carsten Schmuck and
• Jochen Niemeyer

Beilstein J. Org. Chem. 2021, 17, 105–114, doi:10.3762/bjoc.17.11

• BUs via the amino group should result in the necessary concave prearrangement [28]. Force field calculations, carried out in order to determine the optimal distance between LU and BU (see Supporting Information File 1, chapter 8), show that a propionamide is the shortest linker that allows for

Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

• Vladimir Ilkin,
• Vera Berseneva,
• Tetyana Beryozkina,
• Tatiana Glukhareva,
• Lidia Dianova,
• Wim Dehaen,
• Eugenia Seliverstova and
• Vasiliy Bakulev

Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243

• -Aminothiazole-4-N-sulfonyl amidines In spite of the presence of a nucleophilic amino group capable to react with sulfonyl azide to form an azide group, the reaction of azides 2 occurred selectively to the thioamide group of compound 1m. Thus, similar to the reaction of 5-arylamino-1,2,3-triazole-4

• amino group. Thiatriazoles are known to be unstable compounds that readily evolve nitrogen and sulfur upon heating [56]. Conclusion We have shown that the reaction of sulfonyl azides with thioamides can serve as the basis for a general and efficient method for the regioselective synthesis of N-sulfonyl

Ultrasound-assisted Strecker synthesis of novel 2-(hetero)aryl-2-(arylamino)acetonitrile derivatives

• Emese Gal,
• Luiza Gaina,
• Hermina Petkes,
• Alexandra Pop,
• Castelia Cristea,
• Gabriel Barta,
• Dan Cristian Vodnar and
• Luminiţa Silaghi-Dumitrescu

Beilstein J. Org. Chem. 2020, 16, 2929–2936, doi:10.3762/bjoc.16.242

• recorded suggesting the reduced mobility for the proton in the amino group. The presence of the cyano functional group was confirmed by the FTIR spectra displaying an absorption band typical for the stretching vibration of the C≡N bond situated in the 2230–2260 cm−1 region, its position appearing slightly

Synthesis of imidazo[1,5-a]pyridines via cyclocondensation of 2-(aminomethyl)pyridines with electrophilically activated nitroalkanes

• Dmitrii A. Aksenov,
• Nikolai A. Arutiunov,
• Vladimir V. Maliuga,
• Alexander V. Aksenov and
• Michael Rubin

Beilstein J. Org. Chem. 2020, 16, 2903–2910, doi:10.3762/bjoc.16.239

• , entries 2 and 3). To the contrary, an attempt to carry out the reaction in 80% PPA provided a conversion of only 6% even at 140 °C (Table 1, entry 4), whereas no reaction was observed in 100% orthophosphoric acid (Table 1, entry 5). Evidently, under acidic conditions, protonation of the primary amino

• group in 12 attenuates the nucleophilicity of the molecule, rendering the attack on the relatively bulky phosphorylated nitronate 2 inefficient. To prove this, we decided to moderate the basicity of the amine function by protection with a sulfonyl group. Gratifyingly, the N-tosylamine 17 [48] reacted

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• 2 was dissolved in THF and lithium diisopropylamide (LDA) was added, followed by iodine in THF. The reaction temperature was kept strictly between −70 and −80 °C to make sure that iodination proceeds without further side reactions (Scheme 1) [28]. Despite the fact that the exocyclic amino group was

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• °C, 1 d), leading (unexpectedly) to the formation of only one isomer (5a and 6a, respectively) in each case (Scheme 4). Another surprising feature of these reactions was the selective alkylation of the nitrogen atoms of the imidazole ring rather than the amino group. This is in sharp contrast to the

• = 7.69 ppm, 2H, br. s) was observed for the NH2 group. We believe that these observations are consistent with the restricted rotation of the CH(CF3)2 group because of the proximity to the amino group. Theobromine or caffeine both were found to be inert towards tetrakis(trifluoromethyl)-1,3-dithietane (1

• group in compounds 5a and 6a (see Table 2) because of the presence in the β-position relative to the CH(CF3)2 unit of the amino group, which is substantially bigger than a hydrogen atom. Dynamic NMR spectroscopy The broadening of resonances corresponding to the hexafluoroisopropyl moieties in the 19F

Nocarimidazoles C and D, antimicrobial alkanoylimidazoles from a coral-derived actinomycete Kocuria sp.: application of ¹J_C,H coupling constants for the unequivocal determination of substituted imidazoles and stereochemical diversity of anteisoalkyl chains in microbial metabolites

• Md. Rokon Ul Karim,
• Enjuro Harunari,
• Amit Raj Sharma,
• Naoya Oku,
• Kazuaki Akasaka,
• Daisuke Urabe,
• Mada Triandala Sibero and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 2719–2727, doi:10.3762/bjoc.16.222

• both are 4-alkanoyl-5-aminoimidazoles with a 6-methyloctanoyl or decanoyl chain, respectively. Two possible positions of the amino group on the imidazole rings (C-2 and C-5) posed a challenge in the structure study, which was settled by the measurement of 1JC,H coupling constants for comparison with

• correlation from H-2 to C-6 established the linkage between the chain part and the imidazole ring (Figure 2). The remaining question was whether the amino group is bound to C-2 or C-5 in the imidazole ring. A literature survey suggested a diagnostic use of 1JC,H coupling constants [23]. In imidazole and ʟ

• 1 and 4 exhibited weak cytotoxicity against P388 murine leukemia cells, with an IC50 of 38 and 33 μM, respectively. Conclusion Alkanoylimidazoles, 4-acylated imidazoles of varying chain length and terminal branching, with occasional substitution at C-5 by an amino group, are an emerging class of

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• Optics and Nanophotonics, IPCMS, UMR CNRS, 7504, 67034 Strasbourg Cedex 2, France 10.3762/bjoc.16.189 Abstract Herein we report the synthesis and characterization of a new series of styryl-based push-pull dyes containing a free amino group and their Schiff base derivatives. The dyes include the

• series of new styryl-based organic chromophores containing a free amino group and the corresponding Schiff base derivatives. The photophysical, pH sensitivity, NLO properties, and thermal stabilities of all synthesized dyes were investigated. Density Functional Theory (DFT) calculations were also

• dye, started to dissociate at around 310 °C. The Schiff base-based dyes had higher thermal stabilities than the dyes 3–7 having a free amino group. The highest thermal stability was observed for dyes 10–12; their rapid degradation values were above 300 °C. Conclusion In summary, we successfully

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• the availability of the minor groove for small molecule binding (the guanine amino group sterically hinders deep molecule penetration). Homopolynucleotide poly(dA)–poly(dT) is characterised by a peculiar twisted C-DNA structure with a minor groove only half-width of the minor groove of the alternating

Lipophilicity trends upon fluorination of isopropyl, cyclopropyl and 3-oxetanyl groups

• Benjamin Jeffries,
• Zhong Wang,
• Robert I. Troup,
• Anaïs Goupille,
• Jean-Yves Le Questel,
• Charlene Fallan,
• James S. Scott,
• Elisabetta Chiarparin,
• Jérôme Graton and
• Bruno Linclau

Beilstein J. Org. Chem. 2020, 16, 2141–2150, doi:10.3762/bjoc.16.182

• , which leads to a large logD7.4 increase (ΔlogD7.4 +0.73). The modification of a geminal dimethyl moiety to an oxetanyl group has also proven to be a useful biomimetic replacement leading to a significant logP decrease (compare 3 with 4) [16][17][18]. However, when an amino group is located in the α

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• protein chemistry. The peptide bond can exist in two discrete states, commonly designated as trans- and cis-rotamers (ω = 180 and 0°, respectively). The cis-peptide bond is very rare in natural proteins [79], except for the cases when it precedes a proline residue. The secondary amino group of proline

Nonenzymatic synthesis of anomerically pure, mannosyl-based molecular probes for scramblase identification studies

• Giovanni Picca,
• Markus Probst,
• Simon M. Langenegger,
• Oleg Khorev,
• Peter Bütikofer,
• Anant K. Menon and
• Robert Häner

Beilstein J. Org. Chem. 2020, 16, 1732–1739, doi:10.3762/bjoc.16.145

• wherein the NBD can be detected with dithionite. The latter reduces the nitro group of the NBD rapidly into an amino group, rendering the fluorophore nonfluorescent [32][33][34]. While there are no noteworthy difficulties in the synthesis of the molecular probe MPC-1 to report, the same cannot be said for

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• cyclized to form the desired phenanthridine 11.4 in excellent yield. Notably, the reaction could be readily applied to benzoimines having different substituents on the aromatic ring bearing the amino group [73]. Glycine derivatives having a biaryl group attached to the N-terminus were successfully

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

• -membered lactam 138h. The catalytic system Cu(OAc)2/bipyridine (bpy) was applied to perform the oxidative cyclization of unsaturated oximes 139 accompanied by the introduction of an amino group with the formation of isoxazolines 141 and cyclic nitrones 142 (Scheme 47) [136]. The best results were obtained

A cyclopeptide and three oligomycin-class polyketides produced by an underexplored actinomycete of the genus Pseudosporangium

• Shun Saito,
• Kota Atsumi,
• Tao Zhou,
• Keisuke Fukaya,
• Daisuke Urabe,
• Naoya Oku,
• Md. Rokon Ul Karim,
• Hisayuki Komaki and
• Yasuhiro Igarashi

Beilstein J. Org. Chem. 2020, 16, 1100–1110, doi:10.3762/bjoc.16.97

• ''/2''-NH was connected at C-4'' on the basis of the correlations from H-11'' to C-3'' and from H-3'' to C-5''. The connectivity between the carboxy carbon of Pro (C-1') and the amino group of Trp was confirmed by the HMBC correlations from H-2'' and 2''-NH to C-1'. Connectivity between the AcTyr and

Copper-based fluorinated reagents for the synthesis of CF₂R-containing molecules (R ≠ F)

• Louise Ruyet and
• Tatiana Besset

Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92

• CuI, in the presence of t-BuOK and 9,10-phenanthraquinone, the functionalization of a panel of (hetero)aromatic and aliphatic terminal alkynes was achieved (Scheme 5). A good functional group tolerance was observed as alkynes bearing a cyano, ester, bromo or amino group among others were suitable

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• α-hydroxy-β-amino ester 142. In this case, XtalFluor-E was used to activate the OH group in the substrate and displaced by neighboring amino-group participation creating an aziridinium intermediate 150. The latter then was opened stereo- and regioselectively by fluoride to give 151 in good yield and