Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• 29 (31P NMR: ROPPh2 δ = 107 ppm), respectively (Scheme 6). Attempts to carry out a sigmatropic rearrangement in toluene at 100 ºC as well as in xylene at 140 ºC failed. The formation of the phosphine oxide products was not observed by 31P NMR analysis. The probable reason for the lack of the

• chromatography on silica gel. For the purpose of this study, (1R,4R,5R)-apopinenol (16) was subjected to the Mitsunobu reaction to obtain the product with inverted configuration at C4. Alcohol 16 was reacted with diisopropyl azodicarboxylate, triphenylphosphine, and p-nitrobenzoic acid in THF [30]. 1H NMR

• analysis of the crude p-nitrobenzoate 17 revealed a mixture of the predicted p-nitrobenzoate of apopinenol 18 together with an ester of 16 in a ratio of 79:21. Attempts to separate p-nitrobenzoates of 18 and 16 by column chromatography on silica gel failed. The mixture of esters, after purification, was

Indium-mediated C-allylation of melibiose

• Christian Denner,
• Manuel Gintner,
• Hanspeter Kählig and
• Walther Schmid

Beilstein J. Org. Chem. 2019, 15, 2458–2464, doi:10.3762/bjoc.15.238

• optimization procedures (Scheme 2). The overall yield of the isolated epimers was 92%. According to Binder et al. [17] and our own experience [18], we expected the syn-product (2-syn) to be the main diastereomer. However, the determination of the configuration is not possible by NMR analysis. Consequently, the

• -acetylation was conducted leading to a mixture of all four species, indicated by NMR analysis (Scheme 3). In the case of 2-syn the β-pyranose species 5-syn-β was obtained as the main product, besides α-pyranose (5-syn-α) as well as both anomers of the furanoid form (Scheme 4). The overall yield obtained over

• main product turned out to adopt the β-pyranoid form, 5-syn-β and 5-anti-β, respectively, determined by thorough NMR analysis, in an overall yield of 40% and 42% over three steps calculated from epimers 2-syn and 2-anti, respectively. This work demonstrates the indium-mediated allylation reaction to be

Isolation of fungi using the diffusion chamber device FIND technology

• Benjamin Libor,
• Henrik Harms,
• Stefan Kehraus,
• Ekaterina Egereva,
• Max Crüsemann and
• Gabriele M. König

Beilstein J. Org. Chem. 2019, 15, 2191–2203, doi:10.3762/bjoc.15.216

• genus. From the solid, sea-salt containing cultures of H. cf. alpina the ethyl acetate soluble organic compounds were analysed. A first fractionation was achieved by vacuum liquid chromatography (VLC) on reversed-phase material yielding 4 fractions. 1H NMR analysis of these indicated the presence of

• before mentioned conditions to yield 4 subfractions: 3.1–3.4. Fraction 3.2 (44 mg) was analysed with the NMR system. Complex spectra obtained from VLC fraction 3.2 by NMR analysis indicated the presence of a wide range of secondary metabolites. This VLC fraction was thus subsequently subjected to further

Azologization and repurposing of a hetero-stilbene-based kinase inhibitor: towards the design of photoswitchable sirtuin inhibitors

• Christoph W. Grathwol,
• Nathalie Wössner,
• Sören Swyter,
• Adam C. Smith,
• Enrico Tapavicza,
• Robert K. Hofstetter,
• Anja Bodtke,
• Manfred Jung and
• Andreas Link

Beilstein J. Org. Chem. 2019, 15, 2170–2183, doi:10.3762/bjoc.15.214

• methylation was intended to be examined. For UV–vis spectroscopy 50 µM solutions in 5% DMSO (v/v) in enzyme assay buffer were used, as this reflects the enzyme assay conditions. However, for LC-HRMS and NMR analysis, a higher concentration of 10 mM in methanol was necessary to receive reliable chromatograms

• mixtures (Figure 3). Proton NMR analysis implied photostationary states comprising a relative percentage of 45% (Z)-2b and 57% (Z)-2f, respectively after 100 minutes of 254 nm irradiation. The NMR spectra can be found in Supporting Information File 1. The degree of photoisomerization could not be enhanced

Multiple threading of a triple-calix[6]arene host

• Veronica Iuliano,
• Roberta Ciao,
• Emanuele Vignola,
• Carmen Talotta,
• Patrizia Iannece,
• Margherita De Rosa,
• Annunziata Soriente,
• Carmine Gaeta and
• Placido Neri

Beilstein J. Org. Chem. 2019, 15, 2092–2104, doi:10.3762/bjoc.15.207

• + [n × (1.5 × 10−3 mmol), n = 1–6] were dissolved in 0.5 mL of CDCl3. Then, the solution was sonicated for 5 min and transferred in a NMR tube for 1D and 2D NMR spectra acquisition. Determination of Kapp values by quantitative 1H NMR analysis. The samples were prepared by dissolving 6 (1.5 × 10−3 mmol

Characterization of two new degradation products of atorvastatin calcium formed upon treatment with strong acids

• Jürgen Krauß,
• Monika Klimt,
• Markus Luber,
• Peter Mayer and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2085–2091, doi:10.3762/bjoc.15.206

• submitted to extremely strong acidic conditions by refluxing with concentrated (37%) aqueous hydrochloric acid (entry 6), a new product 6 was formed in almost quantitative yield. The 1H NMR analysis clearly indicated that the entire carboxanilide partial structure got lost under these conditions. However

Isolation and characterisation of irinans, androstane-type withanolides from Physalis peruviana L.

• Annika Stein,
• Dave Compera,
• Bianka Karge,
• Mark Brönstrup and
• Jakob Franke

Beilstein J. Org. Chem. 2019, 15, 2003–2012, doi:10.3762/bjoc.15.196

• noted formation of small quantities of irinan A (2) when performing the reaction at 70 °C (Figure 4B and Figure S21 in Supporting Information File 1). The identity of irinan A (2) was verified by isolation of the corresponding compound by preparative HPLC (4% yield) followed by NMR analysis. This result

• NaIO4 reaction was confirmed by NMR analysis. See also Figure S21 in Supporting Information File 1 for extracted ion chromatograms (EICs). 13C and 1H NMR data (CDCl3, 500 MHz, 298 K) of irinans A (2) and B (3) in comparison to the known compound 4β-hydroxywithanolide E (1, CDCl3, 400 MHz, 298 K, δ in

• /MeOH (3:1) and divided into fractions soluble in petroleum ether, chloroform, and n-butanol, respectively. The chloroform fraction was further separated by flash chromatography on a C18 stationary phase, resulting in three major subfractions F1–F3. Final purification by preparative HPLC followed by NMR

Superelectrophilic carbocations: preparation and reactions of a substrate with six ionizable groups

• Sean H. Kennedy,
• Makafui Gasonoo and
• Douglas A. Klumpp

Beilstein J. Org. Chem. 2019, 15, 1515–1520, doi:10.3762/bjoc.15.153

• tri-, tetra-, and pentacationic systems 3–5 provide the pyrido[1,2-a]indole ring system. Interestingly, there was no evidence of the cyclization product 11 (NMR analysis) when compound 9 reacts with superacid in the presence of benzene – product 10 is formed as the major product. These products may be

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• intermolecular hydroarylation of allenes bearing electron-withdrawing substituents. Plausible reaction mechanisms have been proposed on the basis of the investigated reactions, and NMR analysis and DFT studies of the intermediate cationic species. Keywords: aluminum chloride; cation; intermediate

Reaction of oxiranes with cyclodextrins under high-energy ball-milling conditions

• László Jicsinszky,
• Federica Calsolaro,
• Katia Martina,
• Fabio Bucciol,
• Maela Manzoli and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2019, 15, 1448–1459, doi:10.3762/bjoc.15.145

• 60 °C. The GPTS reagent in water was found to be present at around 60–70%, like in case of propylene oxide. Although the neutralised reaction mixture was homogeneous, the isolation and NMR analysis of the isolated product showed poor methoxy content, demonstrating the almost complete hydrolysis of

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• -generated nitrile oxide, which showed inferior selectivity and afforded regio-/stereoisomers [43]. NMR analysis assisted the identification of various isomeric isoxazoline-linked chlorin products. Here, we would like to report an artificial vinylporphyrin 2, which has been designed to control the

Borylation and rearrangement of alkynyloxiranes: a stereospecific route to substituted α-enynes

• Ruben Pomar Fuentespina,
• José Angel Garcia de la Cruz,
• Gabriel Durin,
• Victor Mamane,
• Jean-Marc Weibel and
• Patrick Pale

Beilstein J. Org. Chem. 2019, 15, 1416–1424, doi:10.3762/bjoc.15.141

• isomers. The cis-configured compound cis-1b readily reacted with pinacol phenylboronate 2c under the conditions set up above, providing enyne 4 as the sole product in high yield (Table 2, entry 1). NMR analysis revealed the Z-stereochemistry of this enyne [31]. In contrast, the trans-isomer trans-1b

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• increase in the presence of 5 equivalents of AlCl3. Formation and ratio of these two products could be conveniently established by 1H NMR analysis, due to a difference in the symmetry of products: there are two methyl signals for 10 and a single methyl line at δ 2.81 ppm in the case of 29. Pyrene and

• obtained. The product ratio was established by 1H NMR analysis of the characteristic H-10 proton signal of product 3 (peak resonance doublet at δ 9.2 ppm), which is shifted towards lower magnetic field in quinone 30 (δ 10.0 ppm), and concurrent appearance of singlet for H-3 at δ 9.1 ppm. These experiments

• ); aconversion from NMR analysis; bsolution reaction in flask, substrate/acylation reagent/AlCl3 ratio is 1:1:2.5; ball-milling details are given in Table 1. Scope of aromatic substrates in FCR under mechanochemical activation conditions. aIsolated yields. Mechanochemical regiodirected FCR of anthracene dimer

Genomics-inspired discovery of massiliachelin, an agrochelin epimer from Massilia sp. NR 4-1

• Jan Diettrich,
• Hirokazu Kage and
• Markus Nett

Beilstein J. Org. Chem. 2019, 15, 1298–1303, doi:10.3762/bjoc.15.128

• spectrum of 1. Cañedo and co-workers had previously reported a (14R,15S,17R,19S) relative configuration for 2 [18]. As opposed to the NMR analysis of 2, we detected only a weak NOE correlation between H-14 and H-15. Furthermore, strong NOEs were observed from the N-methyl protons (H3-18) to both, H-17 and

Towards the preparation of synthetic outer membrane vesicle models with micromolar affinity to wheat germ agglutinin using a dialkyl thioglycoside

• Dimitri Fayolle,
• Nathalie Berthet,
• Bastien Doumeche,
• Olivier Renaudet,
• Peter Strazewski and
• Michele Fiore

Beilstein J. Org. Chem. 2019, 15, 937–946, doi:10.3762/bjoc.15.90

• by others [24][25], then the myristoyl group (C14:0) was added using myristoyl chloride in the presence of DMAP (Scheme 1) [26]. NMR monitoring Following the formation of thioglycosides by 1H NMR analysis A test reaction, based on 10 mg of 1a, was performed in deuterated methanol (MeOD) and the

Synthesis of a novel category of pseudo-peptides using an Ugi three-component reaction of levulinic acid as bifunctional substrate, amines, and amino acid-based isocyanides

• Maryam Khalesi,
• Azim Ziyaei Halimehjani and
• Jürgen Martens

Beilstein J. Org. Chem. 2019, 15, 852–857, doi:10.3762/bjoc.15.82

• of an ester functional group in the structure of products makes them suitable substrates for further derivatization. Synthesis of functionalized 5-membered lactams using Ugi reaction. aIsolated yield for mixture of diastereomers. bThe ratio of diastereomers was determined by 1H NMR analysis

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

• Hong Yan,
• Zhong-Yi Mao,
• Zhong-Wei Hou,
• Jinshuai Song and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

• electrochemical synthesis of axially chiral biaryls. Reaction conditions: undivided cell, 2 (0.3 mmol), H2O (1 mL), MeCN (9 mL), 3.5 F mol−1. aIsolated yield of the major diastereomer. bDetermined by 1H NMR analysis of crude reaction mixture. cCombined yield of the two diastereomers. Proposed reaction mechanism

Hoveyda–Grubbs catalysts with an N→Ru coordinate bond in a six-membered ring. Synthesis of stable, industrially scalable, highly efficient ruthenium metathesis catalysts and 2-vinylbenzylamine ligands as their precursors

• Kirill B. Polyanskii,
• Kseniia A. Alekseeva,
• Pavel V. Raspertov,
• Pavel A. Kumandin,
• Eugeniya V. Nikitina,
• Atash V. Gurbanov and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2019, 15, 769–779, doi:10.3762/bjoc.15.73

• the composition of the reaction mixtures by the GС–MS technique only (GC–MS was carried out using external calibration for CM and RCM reactions). The validity of quantitative GC–MS analysis was confirmed by additional LC–MS and 1H NMR analysis of selected reaction mixtures. At the beginning of this

Homo- and hetero-difunctionalized β-cyclodextrins: Short direct synthesis in gram scale and analysis of regiochemistry

• Gábor Benkovics,
• Mihály Bálint,
• Éva Fenyvesi,
• Erzsébet Varga,
• Szabolcs Béni,
• Konstantina Yannakopoulou and
• Milo Malanga

Beilstein J. Org. Chem. 2019, 15, 710–720, doi:10.3762/bjoc.15.66

• spectra amenable to detailed NMR analysis. The unambiguous determination of the regiochemistry of difunctionalized β-CDs was consequently accomplished for the first time without the need for chemical modification, enzymatic degradation or reference material. Moreover, HPLC methods based on reversed-phase

Influence of per-O-sulfation upon the conformational behaviour of common furanosides

• Alexey G. Gerbst,
• Vadim B. Krylov,
• Dmitry A. Argunov,
• Maksim I. Petruk,
• Arsenii S. Solovev,
• Andrey S. Dmitrenok and
• Nikolay E. Nifantiev

Beilstein J. Org. Chem. 2019, 15, 685–694, doi:10.3762/bjoc.15.63

• ][25] of parent furanosides 1–3 was performed by their treatment with an excess of Py·SO3 complex in DMF. After the reaction was finished, the reaction mixture was neutralized with aqueous NH4HCO3, concentrated in vacuo, dried and used for further NMR analysis without additional purification (Scheme 1

Chemical structure of cichorinotoxin, a cyclic lipodepsipeptide that is produced by Pseudomonas cichorii and causes varnish spots on lettuce

• Hidekazu Komatsu,
• Takashi Shirakawa,
• Takeo Uchiyama and
• Tsutomu Hoshino

Beilstein J. Org. Chem. 2019, 15, 299–309, doi:10.3762/bjoc.15.27

• . As described below, NMR analysis of cichorinotoxin confirmed that three units of dehydrothreonine (dhThr: 2-aminobut-2-enoic acid) were present in the toxin, and the Z-geometry of the double bond was determined by NOESY analysis (see Figure 6 and Supporting Information File 1, Figure S10F). Analyses

Systematic synthetic study of four diastereomerically distinct limonene-1,2-diols and their corresponding cyclic carbonates

• Hiroshi Morikawa,
• Jun-ichi Yamaguchi,
• Shun-ichi Sugimura,
• Masato Minamoto,
• Yuuta Gorou,
• Hisatoyo Morinaga and
• Suguru Motokucho

Beilstein J. Org. Chem. 2019, 15, 130–136, doi:10.3762/bjoc.15.13

• ; however, a large coupling constant was clearly observed in CD3OD and in benzene-d6 (Supporting Information File 1, page S42). Conclusion Four diastereomers of (R)-limonene-derived diols (LMdiols) and the corresponding five-membered cyclic carbonates (LM5CCs) were synthesised and characterised by NMR

• analysis. In particular, the NMR data for 2b and 2d exhibit rather similar values. The assignments of 1H and 13C NMR signals were found to provide a means of differentiating the respective diastereomers for the first time. These fundamental studies will contribute to the organic, bioorganic and

Regioselective addition of Grignard reagents to N-acylpyrazinium salts: synthesis of substituted 1,2-dihydropyrazines and Δ⁵-2-oxopiperazines

• Valentine R. St. Hilaire,
• William E. Hopkins,
• Yenteeo S. Miller,
• Srinivasa R. Dandepally and
• Alfred L. Williams

Beilstein J. Org. Chem. 2019, 15, 72–78, doi:10.3762/bjoc.15.8

• N-triflate pyrazinium salts [12]. 1H NMR analysis confirmed this by showing a rotameric pair of singlets at 3.89 and 3.84 ppm for the methoxy group at C3, a rotameric pair of singlets at 5.89 and 5.58 ppm for the proton at C2 and a rotameric pair of doublets at 6.17, 6.15 ppm and 6.68, 6.63 ppm for

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• Merck. For 1H and 13C NMR analysis a Bruker Avance I 400 MHz instrument was used with 400 MHz for 1H spectra, 162 MHz for 31P spectra and 101 MHz for 13C spectra or a Bruker Avance I 500 MHz instrument was used with 500 MHz for 1H spectra and with 126 MHz for 13C spectra. The allocation of NMR signals

1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation

• A. S. Antonov,
• A. F. Pozharskii,
• P. M. Tolstoy,
• A. Filarowski and
• O. V. Khoroshilova

Beilstein J. Org. Chem. 2018, 14, 2940–2948, doi:10.3762/bjoc.14.273

• . Structural investigations The structural investigations started with a 1H NMR analysis of the imines 4a–7a in acetone-d6, CD3CN and DMSO-d6 in a wide range of temperatures. The main attention was paid to the chemical shift and the shape of the C=NH and NMe2 groups’ signals. Upon temperature decrease, the NH