A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• affording 2a after protonation and thus regenerating the catalyst intermediate 3. 1H NMR analysis using CD3CN showed high levels of HCCl3, which could be form after decarboxylation of the basic species. In an attempt to obtain a better understanding at this dimerization reaction and to give new insights

• . Reactions were carried out using 0.45 mmol of 1 and 0.14 mmol of salt. Diastereomer ratio measured by 1H NMR analysis of the crude reaction mixture. Sterically bulky azlactone enol derivatives. Reduction of 2c. Optimization reaction conditions of azlactones dimerization. Supporting Information Supporting

Consecutive hydrazino-Ugi-azide reactions: synthesis of acylhydrazines bearing 1,5-disubstituted tetrazoles

• Angélica de Fátima S. Barreto,
• Veronica Alves dos Santos and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2017, 13, 2596–2602, doi:10.3762/bjoc.13.256

• stage, only symmetrical ketones were used to facilitate the product characterization by NMR analysis. Indeed the 1H and 13C NMR spectra were in full agreement with the proposed structures. Of note are the characteristic C=N tetrazole resonances that are observed between 155–158 ppm in the 13C NMR

¹⁵N-Labelling and structure determination of adamantylated azolo-azines in solution

• Sergey L. Deev,
• Alexander S. Paramonov,
• Tatyana S. Shestakova,
• Igor A. Khalymbadzha,
• Oleg N. Chupakhin,
• Julia O. Subbotina,
• Oleg S. Eltsov,
• Pavel A. Slepukhin,
• Vladimir L. Rusinov,
• Alexander S. Arseniev and
• Zakhar O. Shenkarev

Beilstein J. Org. Chem. 2017, 13, 2535–2548, doi:10.3762/bjoc.13.250

• complicated the subsequent NMR analysis. Meanwhile, the application of [2,3-15N2]-5-aminotetrazole 7-15N2 provided the single double-labelled products in the tetrazolo[1,5-a]pyrimidine series [33]. Thus, in the current work, [2,3-15N2]-5-aminotetrazole 7-15N2 (98% enrichment for each of the labelled 15N atoms

• -labelled non-adamantylated precursor 13-15N2 (isotopic enrichment 98%) were refluxed for 2 h in TFA without the addition of 1-adamantanol (14, Scheme 4). NMR analysis of the resulting mixture revealed the compounds 13*-15N2, 15a*-15N2, and 15b*-15N2 in a 5:2:3 ratio. The observed equal 15N-isotopic

Synthesis of naturally-derived macromolecules through simplified electrochemically mediated ATRP

• Paweł Chmielarz,
• Tomasz Pacześniak,
• Katarzyna Rydel-Ciszek,
• Izabela Zaborniak,
• Paulina Biedka and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2017, 13, 2466–2472, doi:10.3762/bjoc.13.243

• , and 1H NMR prove the successful preparation of the star-shaped polymers. These new polymer materials create potential possibilities of using them as key elements of biologically active thin films in tissue engineering and as drug delivery systems. 1H NMR analysis of QC-Br5 (Mn = 1,050, Ð = 1.11) after

Synthesis, effect of substituents on the regiochemistry and equilibrium studies of tetrazolo[1,5-a]pyrimidine/2-azidopyrimidines

• Elisandra Scapin,
• Paulo R. S. Salbego,
• Caroline R. Bender,
• Alexandre R. Meyer,
• Anderson B. Pagliari,
• Tainára Orlando,
• Geórgia C. Zimmer,
• Clarissa P. Frizzo,
• Helio G. Bonacorso,
• Nilo Zanatta and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 2396–2407, doi:10.3762/bjoc.13.237

• the azide in both solvents evaluated. Unexpectedly, the tetrazole form is slightly more stable in CDCl3 when CX3 is bonded at the 7-position of the ring. Moreover, the 15N NMR analysis was carried out for compounds 6a and 6g. The spectra of the phenyl-substituted compound 6a, in CDCl3, showed a signal

Fluorination of some highly functionalized cycloalkanes: chemoselectivity and substrate dependence

• Attila Márió Remete,
• Melinda Nonn,
• Santos Fustero,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2017, 13, 2364–2371, doi:10.3762/bjoc.13.233

• treatment of dihydroxylated amino acid ester (±)-1 with 1.5 equiv of Deoxofluor after 70 min afforded through intramolecular cyclization a compound which was identified on the basis of 2D NMR analysis as oxazoline derivative (±)-2 as the sole product in 71% yield. When the same reaction was carried out in

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

• ketones [31]. However, 1H NMR and 19F NMR analysis of the crude reaction mixture revealed that the only identifiable product was the undesired gem-difluorinated compound 25 (Scheme 2), which was obtained along with a significant amount of unreacted starting material 21a (see Supporting Information File 1

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• ) to avoid the formation of complex product mixtures. Based on the 1H NMR analysis, only one product, identical in reactions with E- and with Z-1b, was formed [47]. Also bis(dimethylamino)-substituted 1,3-dienes including bicyclic representatives were used for reactions with E- and Z-1b [48][49

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• perbenzoylated donor 83, the α-glycosyl triflate 84 was formed as the major intermediate [56][58][59]. When the more electron-rich donor 85 was preactivated, the dioxalenium ion 86 via the participation of the 2-benzoyl (Bz) group was found as the dominating species from NMR analysis (Figure 3) [57

Remarkable functions of sn-3 hydroxy and phosphocholine groups in 1,2-diacyl-sn-glycerolipids to induce clockwise (+)-helicity around the 1,2-diacyl moiety: Evidence from conformation analysis by ¹H NMR spectroscopy

• Yoshihiro Nishida,
• Mengfei Yuan,
• Kazuo Fukuda,
• Kaito Fujisawa,
• Hirofumi Dohi and
• Hirotaka Uzawa

Beilstein J. Org. Chem. 2017, 13, 1999–2009, doi:10.3762/bjoc.13.196

• phosphates). The 1H NMR analysis indicated that the helical property around the 1,2-diacyl moiety is considerably affected by these sn-3 substituents. The sn-3 hydroxy group induced a unique helical property, which was considerably dependent on the solvents used. In CDCl3 solution, three staggered conformers

• used. From the 1H NMR analysis, the helical conformational properties around the 1,2-diacyl moiety conformed to a simple empirical rule, which permitted the proposal of a conformational diagram for 1,2-dipalmitoyl-sn-glycerols in the solution states. Keywords: cell membrane; chirality; conformation

• (C/M = 2:1), the solvation by methanol-d4 might be partly replaced with D2O. Hamilton et al. [30] employed 13C NMR spectroscopy to examine the dynamic molecular behavior of 1,2-dilauroyl-sn-glycerol located in liposomes mixed with glycerophospholipids. Their 13C NMR analysis revealed that the

Solid-state mechanochemical ω-functionalization of poly(ethylene glycol)

• Michael Y. Malca,
• Pierre-Olivier Ferko,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2017, 13, 1963–1968, doi:10.3762/bjoc.13.191

• determined by integration of peaks attributed to the methylene hydrogens geminal to the ω-functionality of mPEG, namely hydroxy, for the starting material, and the functionality introduced in the reaction explained below, for the products. p-Xylene was used as an internal standard for 1H NMR analysis, and

A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

• Grzegorz Mlostoń,
• Paulina Pipiak,
• Róża Hamera-Fałdyga and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185

• the reagents in a ratio of 3:1. Under these conditions, 1,3-dithiolane 6a was formed almost exclusively with only traces of 1,4-dithiane 7 as revealed by 1H NMR analysis of the crude reaction mixture. Desilylation of 6a occurred quantitatively and the known tetraphenylethylene (9a) [26] was obtained

• after ca. 15 min (TLC, petroleum ether/CH2Cl2 8:2). Then, a solution of TBAF (1 M in THF, 1 mL, 1 mmol) was added. After complete reaction (TLC, petroleum ether/CH2Cl2 8:2), the solvent was removed under vacuum, and the residue was subjected to 1H NMR analysis in CDCl3 solution. The crude products 9a–f

• removal of the solvent under vacuum, the residue was subjected to 1H NMR analysis in CDCl3 solution. The crude products were purified by column chromatography. 2,2’-[(9H-Fluoren-9-ylidene)methylene]dithiophene (9i): Yield: 132 mg (77%); chromatographic purification (petroleum ether/CHCl3 7:3). Orange

Iodoarene-catalyzed cyclizations of N-propargylamides and β-amidoketones: synthesis of 2-oxazolines

• Somaia Kamouka and
• Wesley J. Moran

Beilstein J. Org. Chem. 2017, 13, 1823–1827, doi:10.3762/bjoc.13.177

• precatalyst in the presence of p-toluenesulfonic acid and m-chloroperbenzoic acid in acetonitrile, 4a cyclized to 6a in 92% yield as determined by 1H NMR analysis of the crude reaction mixture (Table 1, entry 1). In line with our previous findings with N-alkenylamides, the use of iodobenzene in place of 2

An efficient Pd–NHC catalyst system in situ generated from Na₂PdCl₄ and PEG-functionalized imidazolium salts for Mizoroki–Heck reactions in water

• Nan Sun,
• Meng Chen,
• Liqun Jin,
• Wei Zhao,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 1735–1744, doi:10.3762/bjoc.13.168

• NMR spectrum, which is similar to the reported 13C NMR analysis for Pd–NHC species [66]. It is strongly suggested that a Pd–NHC complex was formed from deprotonation of L1 under the reaction conditions. However, the exact structure of this complex is not clear yet. With the preliminary reaction

Synthesis and metal binding properties of N-alkylcarboxyspiropyrans

• Alexis Perry and
• Christina J. Kousseff

Beilstein J. Org. Chem. 2017, 13, 1542–1550, doi:10.3762/bjoc.13.154

• complexes absorb strongly in the visible range (often 450–600 nm), giving rapid access to clear, quantitative data at low concentrations and without interference from paramagnetic transition metal cations (a feature which causes significant problems with NMR analysis). Conversely, use of bound merocyanine

• of divalent metal cation; (ii) ε decreases slightly with increasing chain length. Unexpectedly, 1H NMR analysis of C3SP in the presence of Zn2+ and Mg2+ produced complex and intractable spectra and it would appear that these metal salts are able to promote degradation of this compound. Irrespective

Phenylsilane as an effective desulfinylation reagent

• Wanda H. Midura,
• Aneta Rzewnicka and
• Jerzy A. Krysiak

Beilstein J. Org. Chem. 2017, 13, 1513–1517, doi:10.3762/bjoc.13.150

• , in the absence of an α-proton at the sulfinyl group which was conclusive in our former studies, we benefited from 13C NMR analysis. The small value of coupling constant 3JP-C = 4 Hz indicated a trans relationship between the carboxylate and the phosphoryl substituent. Desulfinylation of cyclopropane

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• borylated product 3a. In addition to the 1H NMR analysis in solution, this result was confirmed by immediate ex situ analysis using IR spectroscopy of the solid reaction mixture, which revealed only the presence of both starting materials. Thereby, excluding a direct thermal [20][21] or photolysis pathway

• heating. NMR analysis of the molten 1d revealed the presence of 1-fluoro-4-iodobenzene (for details, see Supporting Information File 1). Therefore, the difference in melting point temperatures of the substrates and their thermal stability could have a direct correlation with the observed reactivity in the

Photocatalyzed synthesis of isochromanones and isobenzofuranones under batch and flow conditions

• Manuel Anselmo,
• Lisa Moni,
• Hossny Ismail,
• Davide Comoretto,
• Renata Riva and
• Andrea Basso

Beilstein J. Org. Chem. 2017, 13, 1456–1462, doi:10.3762/bjoc.13.143

• decomposed during 13C NMR analysis). The interest of both academia and industry in flow chemistry has recently increased. In particular, photochemical reactions performed under continuous flow have been proven particularly effective [6], as the reduced size of the reaction channels allows for a more

A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

• Marcel Reimann,
• Louis P. Sandjo,
• Luis Antelo,
• Eckhard Thines,
• Isabella Siepe and
• Till Opatz

Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140

• aged DMF was used for this purpose. In fresh DMF, hydrogenolysis smoothly produced amine 7 instead. When the crude peptide was coupled to the GHPD side chain unit 3, HPLC showed only a single peak with the correct m/z ratio. This compound 24 was isolated by preparative HPLC and NMR analysis showed a

Construction of highly enantioenriched spirocyclopentaneoxindoles containing four consecutive stereocenters via thiourea-catalyzed asymmetric Michael–Henry cascade reactions

• Yonglei Du,
• Jian Li,
• Kerong Chen,
• Chenglin Wu,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2017, 13, 1342–1349, doi:10.3762/bjoc.13.131

• chiral HPLC analysis of major diastereomer. The dr values were determined by 1H NMR analysis. Method A: with 10 mol % of d as a catalyst, −20 °C, 12 h. Method B: with 10 mol % of d as a catalyst, −10 °C, 24 h. A plausible mechanism. Optimization for the reaction conditionsa. Supporting Information

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• reaction compared to when the compound was synthesized via the two-step process (Table 4). Lastly, the macrocycle 4m was acetylated in pyridine using acetyl chloride and a catalytic amount of DMAP to furnish diacetate 5. The 1H NMR analysis of 5 clearly showed presence of two singlets at δ 2.08 and 2.06

Synthesis and enzymatic ketonization of the 5-(halo)-2-hydroxymuconates and 5-(halo)-2-hydroxy-2,4-pentadienoates

• Tyler M. M. Stack,
• William H. Johnson Jr. and
• Christian P. Whitman

Beilstein J. Org. Chem. 2017, 13, 1022–1031, doi:10.3762/bjoc.13.101

• NMR analysis indicated that the product formed was ethyl 2,3-dibromobutyrate. Subsequently, ethyl 2,3-dibromobutyrate was converted to ethyl 2-bromocrotonate following the procedure used to convert ethyl 2,3-dichlorobutyrate to ethyl 2-chlorocrotonate [11]. Syntheses of 5-(halo)-2-hydroxymuconate (3c

Use of costic acid, a natural extract from Dittrichia viscosa, for the control of Varroa destructor, a parasite of the European honey bee

• Kalliopi Sofou,
• Demosthenis Isaakidis,
• Apostolos Spyros,
• Anita Büttner,
• Athanassios Giannis and
• Haralambos E. Katerinopoulos

Beilstein J. Org. Chem. 2017, 13, 952–959, doi:10.3762/bjoc.13.96

• . It has been previously isolated from D. viscosa and its structure was confirmed via NMR analysis [36][37][38]. Moreover, D. viscosa is not the only species containing costic acid as a metabolite. It has been reported in the literature as a component in other plants such as Nectandra cissiflora, Nees

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

• ionization like matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI). Liquid chromatography (LC) separation with evaporative light scattering detection (ELSD) and NMR analysis were employed in order to elucidate the structural profiles of the obtained mixtures. The results

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

• yielding 11 fractions. 1H NMR analysis of these indicated the presence of chemically diverse secondary metabolites in the major fractions 3–8, whereas the hydrophilic fractions 1 and 2 merely contained sugars and the lipophilic ones, i.e., 9–11 simple lipids. Detailed UPLC–HRMS investigation was thus