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

• and 13c were determined using NMR spectra. The exact locations of the olefinic carbon (=CH) in 12c and methylene group in 13c were determined from 2D NMR (HSQC and HMBC) spectra. The 1H NMR spectrum of pyrrolopyrazinone derivative 12c shows the presence of two NH2 protons resonating at 4.41 ppm as a

Synthesis of D-manno-heptulose via a cascade aldol/hemiketalization reaction

• Yan Chen,
• Xiaoman Wang,
• Junchang Wang and
• You Yang

Beilstein J. Org. Chem. 2017, 13, 795–799, doi:10.3762/bjoc.13.79

• to synthesize the 2-OH-protected C4 aldehyde for the assembly of the seven-carbon skeleton. Thus, acetylation of the 2-OH group in 7 with acetic anhydride and DMAP in dichloromethane provided ester 8 in 86% yield. The positions of the 2-acetyl and 3-PMB groups were determined by 1H, 13C and 2D NMR

• , and 2D NMR spectra (see Supporting Information File 1 for details). The anomeric α-configuration of compound 2 was confirmed by analysis of the NOE effects between the C-1 hydrogen and the C-5 hydrogen. With the ketoheptose building block 2 in hand, we turned our attention to the synthesis of D-manno

Cyclodextrins tethered with oligolactides – green synthesis and structural assessment

• Cristian Peptu,
• Mihaela Balan-Porcarasu,
• Alena Šišková,
• Ľudovít Škultéty and
• Jaroslav Mosnáček

Beilstein J. Org. Chem. 2017, 13, 779–792, doi:10.3762/bjoc.13.77

• , DEPT135-NMR and 2D NMR spectroscopy (Supporting Information File 1, Figures S24–S31). In the 13C NMR spectra of β-CD-LA F1 and F2 (Figure 5), the peaks assigned to C5’ (69.1 ppm) and C6’ (64.4 ppm) of the substituted glucopyranose unit are clearly isolated. The rest of the peaks for the carbons of the

• spectra were performed using 2D NMR experiments (H,H-COSY, H,C-HMQC, H,C-HMBC). The molecular parameters of the cyclodextrin–oligolactide covalent conjugates were also determined by GPC using a Shimadzu LC-20 isocratic pump and a Shimadzu refractive index detector in size exclusion mode using a PSS PFG

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• using the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The molecular conjugates, well soluble in aqueous medium, were extensively characterized by 1D and 2D NMR spectroscopy and mass spectrometry. Preliminary spectroscopic investigations showed that the β

• permanently immobilized on the silica gel column and only the targeted dibromofluorescein (3) was eluted. The structure of compound 3 was elucidated with the aid of 1D and 2D NMR experiments (Supporting Information File 1, Figures S10–S14). In the following step, dibrominated fluorescein 3 was nitrated using

• , Supporting Information File 1) and the in-depth analysis of the DEPT-edited HSQC spectra supported by COSY data (Figures S23 and S31, Supporting Information File 1), allowed the complete assignment of the aromatic resonances. Additional 2D NMR spectra (HMBC and ROESY) for the eosin–β-CD conjugates are also

Secondary metabolome and its defensive role in the aeolidoidean Phyllodesmium longicirrum, (Gastropoda, Heterobranchia, Nudibranchia)

• Alexander Bogdanov,
• Cora Hertzer,
• Stefan Kehraus,
• Samuel Nietzer,
• Sven Rohde,
• Peter J. Schupp,
• Heike Wägele and
• Gabriele M. König

Beilstein J. Org. Chem. 2017, 13, 502–519, doi:10.3762/bjoc.13.50

• ., compounds 8 and 9. The planar structure of 8 and 9 was established as that of isosarcophine by 1D and 2D NMR data (1H, 13C, COSY, HSQC and HMBC). Specific optical rotation measurements in chloroform (c 0.1 each substance) yielded [α]D20 values of +92.0 for 8 and −38.0 for 9. Due to the close similarity of

• –46.7, c 0.9 in chloroform) for the cembranoid bisepoxide isolated from the soft coral Sarcophyton sp., pointing towards the same structure for this secondary metabolite. However, no 2D NMR data or stereochemistry of this molecule was reported up to now. Here we include the results of 2D NMR (COSY, HMBC

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• solvent lines and it is more frequency selective than other techniques. In contrast, pre-saturation do not work well in flowing samples and it is slower in its recycle rate. WET has also been incorporated into all of the standard 2D NMR sequences [28]. As an example Figure 3 shows a NOESY pulse sequence

• including DEPT spectra, 2D-NMR spectroscopy, 19F NMR spectroscopy and monitoring of the stereoselectivity in Diels–Alder reactions and self-optimization of flow conditions using a modified version of the Nelder–Mead algorithm. For the NMR integral data for each experiment, the algorithm (Figure 15) selects

• possibilities of development and innovation. Further developments in microchip technology, microcoils (higher sensitivity, broadband and 2D NMR applications [52]) and improved sensitivity for benchtop NMR instruments, together with the development of new and improved software for product analysis and reaction

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• , to give 3-hydroxynaphtho[1,2-b]quinolizinium bromide (2) in 49% yield. The new compounds 2 and 5 were identified and characterized by 1D- und 2D-NMR spectroscopy, mass spectrometry and elemental analysis. Absorption and emission properties The absorption and emission properties of

Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones

• Vinicius R. Campos,
• Ana T. P. C. Gomes,
• Anna C. Cunha,
• Maria da Graça P. M. S. Neves,
• Vitor F. Ferreira and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2017, 13, 195–202, doi:10.3762/bjoc.13.22

• -vinylporphyrin derivatives 3a–c The structures of the new β-vinylporphyrin derivatives 3a–c were assigned on the basis of their 1H and 13C NMR spectra and their molecular formulae were confirmed by HRMS–ESI+. 2D NMR spectra [COSY, HMBC, HSQC] were also obtained to unequivocally identify proton and carbon

Synthesis of structurally diverse 3,4-dihydropyrimidin-2(1H)-ones via sequential Biginelli and Passerini reactions

• Andreas C. Boukis,
• Baptiste Monney and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2017, 13, 54–62, doi:10.3762/bjoc.13.7

• reactions, a large number of structurally diverse compounds could be synthesized. In addition, a one-pot Biginelli–Passerini tandem reaction was demonstrated. All products were carefully characterized via 1D and 2D NMR as well as IR and HRMS. Keywords: Biginelli reaction; molecular diversity

Multicomponent synthesis of spiropyrrolidine analogues derived from vinylindole/indazole by a 1,3-dipolar cycloaddition reaction

• Manjunatha Narayanarao,
• Lokesh Koodlur,
• Vijayakumar G. Revanasiddappa,
• Subramanya Gopal and
• Susmita Kamila

Beilstein J. Org. Chem. 2016, 12, 2893–2897, doi:10.3762/bjoc.12.288

• cyclic amino acid L-proline (6) which was reacted with 3 under the optimized reaction conditions. The corresponding stereo- and regiospecific isomers of spiropyrrolidines 8 were obtained in good yields (Table 1, entries 12–22). The stereochemical assignments for compounds 8 were supported by 2D NMR data

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

• Loïc Leclercq

Beilstein J. Org. Chem. 2016, 12, 2644–2662, doi:10.3762/bjoc.12.261

• sweet-taste profile. In this context, Thordarson et al. studied the interaction of α-CD with thaumatin [93]. The 1D and 2D NMR experiments revealed that α-CD binds to aromatic residues of thaumatin with a binding constant of 8.5 M−1. As the active binding site of the thaumatin protein is known, the

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

• and the substituent on the exocyclic nitrogen atom governs the ratio of these tautomers. Isomers with the alkyl group in the endocyclic position can be obtained from N-methyl(ethyl)thioureas. 2D NMR spectroscopy and DFT calculations rationalize experimental results. Keywords: maleimides

• interconverting E/Z-isomers at the exocyclic C=N bond (given in parentheses on Scheme 2) could be involved. Therefore we have thoroughly analyzed the spectroscopic data of thiazolidine 3a from 2D NMR experiments (NOESY, 13C,1H and 15N,1H-HSQC and HMBC) and made a full assignment of all signals. A large difference

• Supporting Information File 324: Experimental procedures, characterization data and copies of the 1H, 13C and 2D NMR spectra; X-ray analysis data for thiazolidine 3b. Acknowledgements The work was supported by a grant of the President of Russian Federation (no. MK-5965.2016.3). NMR, HRMS, and XRD analyses

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• . Incompletely substituted derivatives were in the majority in the product, as can be seen in the multiple anomeric proton peaks in the 1H NMR spectra and the CH2-halogen signals in the 2D NMR spectra. The larger excess of TU gave the complete substitution of the halogen (entries 3, 4, 9–11 in Table 1), but the

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• products possibly deriving by polycondensations or eliminations after the aldol condensation. The structure and stereochemistry of inososes 5–8, 11, and 12 were confirmed by 1H, 13C and 2D NMR experiments. For example, the conformation of inosose 6 was established by the similar value of the vicinal proton

• good agreement with what has been reported before on similar compounds [45]. The structure and stereochemistry of inositols 13–19 were confirmed by 1H, 13C and 2D NMR experiments directly or after per-acetylation of the reduction product and/or through comparison with previously reported compounds

New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242

• Ze’en Xiao,
• Senhua Chen,
• Runlin Cai,
• Shao’e Lin,
• Kui Hong and
• Zhigang She

Beilstein J. Org. Chem. 2016, 12, 2077–2085, doi:10.3762/bjoc.12.196

• -DECA mass spectrometer and HRESIMS spectra were determined on a Shimadzu LCMS-IT-TOF mass spectrometer. 1D and 2D NMR spectra were carried out on Bruker Avance 400 spectrometer (1H 400 MHz, 13C 100 MHz). Chemical shifts (δ) are given in ppm with reference to the solvent signal (δC 77.1/δH 7.26 for

• : 1D and 2D NMR, HREIMS, and HRESIMS spectra of the new compounds. Acknowledgements We thank the National Natural Science Foundation of China (21472251, 41276146), the Science & Technology Plan Project of Guangdong Province of China (2013B021100011), the Key project of Natural Science Foundation of

Varioloid A, a new indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291

• Peng Zhang,
• Xiao-Ming Li,
• Xin-Xin Mao,
• Attila Mándi,
• Tibor Kurtán and
• Bin-Gui Wang

Beilstein J. Org. Chem. 2016, 12, 2012–2018, doi:10.3762/bjoc.12.188

• indolyl-6,10b-dihydro-5aH-[1]benzofuro[2,3-b]indole derivative, varioloid A (1), was isolated from the marine alga-derived endophytic fungus Paecilomyces variotii EN-291. Its structure was elucidated on the basis of extensive analysis of 1D and 2D NMR data and the absolute configuration was determined by

• , measured in CDCl3). Supporting Information Supporting Information File 444: Selected 1D and 2D NMR spectra of compounds 1 and 2, and computed solvent model ECD spectrum of compound 1. Acknowledgments Financial support from the Natural Science Foundation of China (31330009) and from the Scientific and

Synthesis and NMR studies of malonyl-linked glycoconjugates of N-(2-aminoethyl)glycine. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger,
• Sven Hafner and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 1939–1948, doi:10.3762/bjoc.12.183

• and 1b (see 2D NMR investigations below). The 1H NMR spectrum of the dimeric PNA glycoconjugate 4 in CDCl3 showed the presence of four different rotameric structures (see also Figure 3). This was evident from eight distinct doublet signals for the anomeric amide protons (Figure 6). Here, no

• unambiguous assignment of the observed doublets to respective cis/trans rotameric forms could be achieved by 2D NMR spectroscopy. Since deuterochloroform is not suitable for temperature-dependent 1H NMR experiments at higher temperatures which, in turn, are necessary for determining the coalescence

• –368 K). Figure 11 finally shows the temperature-dependent 1H NMR spectra (9.10–7.80 ppm are only) of 4 in the range between 25 and 100 °C. In this case, the corresponding coalescence temperature (Tc) could also be determined at 90–95 °C (363–368 K). 2D-NMR investigation In order to unambiguously

Unusual reactions of diazocarbonyl compounds with α,β-unsaturated δ-amino esters: Rh(II)-catalyzed Wolff rearrangement and oxidative cleavage of N–H-insertion products

• Valerij A. Nikolaev,
• Jury J. Medvedev,
• Olesia S. Galkina,
• Ksenia V. Azarova and
• Christoph Schneider

Beilstein J. Org. Chem. 2016, 12, 1904–1910, doi:10.3762/bjoc.12.180

• in the yields of up to 50% (Table 2, entries 5–9) in parallel with the Wolff rearrangement product 6с (18–79%; Table 2, entries 4–7). The structures of these compounds were established by 1H and 13C NMR, 2D NMR (H,H-COSY, HMBC, HSQC) spectra, as well as by comparison with the literature data in the

Beta-hydroxyphosphonate ribonucleoside analogues derived from 4-substituted-1,2,3-triazoles as IMP/GMP mimics: synthesis and biological evaluation

• Tai Nguyen Van,
• Audrey Hospital,
• Corinne Lionne,
• Lars P. Jordheim,
• Charles Dumontet,
• Christian Périgaud,
• Laurent Chaloin and
• Suzanne Peyrottes

Beilstein J. Org. Chem. 2016, 12, 1476–1486, doi:10.3762/bjoc.12.144

• Information File 1). NMR studies To establish the stereochemistry and/or regiochemistry of the azidation and CuAAC steps, homo- or heteronuclear 2D NMR experiments (see Supporting Information File 2) were performed on compounds 2 and 3a (Figure 2). In addition, we synthesized compound 5 (resulting from an 1,5

• and 5 demonstrates that cycloaddition of terminal alkynes catalysed by Cu(I) were highly regioselective and led to 4-substituted-1,2,3-triazoles in the β-hydroxyphosphonate series. Then, on the basis of the study reported by Hudson et al., we performed extensive 2D-NMR experiments on compounds 3h and

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• C21H19NFe2. A tiny peak cluster at m/z = 693, assignable to the loss of CO from W(CO)5(E-2), and peaks at higher m/z ratios, assignable to tungsten clusters, are also observed when traces of oxygen/water were present. Using 1H and 13C NMR spectroscopy as well as 2D NMR (1H,1H COSY, 1H,1H NOESY, 13C,1H HSQC

Marine-derived myxobacteria of the suborder Nannocystineae: An underexplored source of structurally intriguing and biologically active metabolites

• Antonio Dávila-Céspedes,
• Peter Hufendiek,
• Max Crüsemann,
• Till F. Schäberle and
• Gabriele M. König

Beilstein J. Org. Chem. 2016, 12, 969–984, doi:10.3762/bjoc.12.96

• ]. The complete structure was elucidated via 2D NMR techniques, while NOESY correlations were used to study the configuration of the double bonds. However, the configuration at the epoxide bearing carbon atoms could not be resolved at that time. In further work, Kundim et al. [53] published three new

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• resonances in the 1H and 13C NMR spectra including endo and exo atoms of the methylene groups (CH2) was accomplished by combining 1H, 13C, DEPT and 2D NMR data (HSQC, HMBC and NOESY). In the 1H NMR spectrum (Figure 3) two sets of two signals of equal intensity in the range of 1.2 to 0.80 ppm are consistent

• isomer. The optimized structure of the (S)-3A isomer is displayed in Figure 5. Assuming that to observe NOE effects in the 2D NMR spectra a distance lower than ca. 3 Å between the hydrogen atoms is required, the calculated structures indicate that H3A should show a strong NOE to H10A (one of the methyl

Three new trixane glycosides obtained from the leaves of Jungia sellowii Less. using centrifugal partition chromatography

• Luíse Azevedo,
• Larissa Faqueti,
• Marina Kritsanida,
• Antonia Efstathiou,
• Despina Smirlis,
• Gilberto C. Franchi Jr,
• Grégory Genta-Jouve,
• Sylvie Michel,
• Louis P. Sandjo,
• Raphaël Grougnet and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2016, 12, 674–683, doi:10.3762/bjoc.12.68

• spraying with sulfuric vanillin solution at 30% and heating. The mobile phase used to monitor the method development and the fractions was composed by EtOAc/CH2O2/AcOH/H2O (60:0.6:0.6:20). The 1D and 2D NMR experiments were recorded with Bruker AC-300 and Bruker Avance-400 spectrometers at 400 MHz for 1H

• and 2D NMR and at 75 MHz for 13C NMR. The spectra were recorded using deuterated solvents CDCl3 and CD3OD. Chemical shifts (δ) are expressed in ppm with reference to the TMS signal (δH/δC 0.0) and coupling constants are reported in Hz. The 2D NMR experiments (COSY, HSQC, HMBC, and NOESY) were

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• designated as the syn and anti isomers in which, for example, the high-priority substituents at Р-1 and С-3 are proximate in the syn isomer. Using the homo- and heteronuclear 2D NMR spectroscopy (H,H-COSY, HSQC, HMBC), parameters of the NMR spectra of some compounds 2 were determined and proved to agree with

Supramolecular structures based on regioisomers of cinnamyl-α-cyclodextrins – new media for capillary separation techniques

• Gabor Benkovics,
• Ondrej Hodek,
• Martina Havlikova,
• Zuzana Bosakova,
• Pavel Coufal,
• Milo Malanga,
• Eva Fenyvesi,
• Andras Darcsi,
• Szabolcs Beni and
• Jindrich Jindrich

Beilstein J. Org. Chem. 2016, 12, 97–109, doi:10.3762/bjoc.12.11

• the aggregation behavior of Cin-α-CDs, we further investigated its interaction with both regioisomers using 1D and 2D NMR experiments to get a deeper insight into the disaggregation process. ROESY and 1H NMR spectra of isomer 2 or isomer 3 were recorded in the presence of CioOK (5-fold molar excess

• characterization of two regioisomers of monocinnamyl-α-CD, which allowed their gram-scale preparation and their application as background electrolyte additives in capillary electrophoresis. A set of 2D NMR experiments were used to elucidate the structures of the prepared derivatives, thus to distinguish the two

• elucidation of 2D NMR spectra of 2-O-Cin-α-CD. 2D ROESY spectrum of 2-O-Cin-α-CD in D2O at 25 °C at 24 mM concentration. Expansion of the 2D ROESY spectrum of 2-O-Cin-α-CD indicating the geometric arrangement. 1H NMR spectra of 2-O-Cin-α-CD in D2O at 25 °C at different concentrations. 1H NMR spectra of 3-O