Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• laboratory of the department using a Eurovektor Hekatech EA-3000 elemental analyzer. Melting points were measured on a Wagner and Munz Poly Therm A system and are not corrected. X-ray crystallography Crystallographic data for compound 3 were collected on Bruker D8 VENTURE Kappa Duo PHOTON200 by IμS micro

An air-stable bisboron complex: a practical bidentate Lewis acid catalyst

• Longcheng Hong,
• Sebastian Ahles,
• Andreas H. Heindl,
• Gastelle Tiétcha,
• Andrey Petrov,
• Zhenpin Lu,
• Christian Logemann and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 618–625, doi:10.3762/bjoc.14.48

• experimental procedures, copies of 1H and 13C NMR spectra, UV–vis spectra as well as the X-ray crystallography. Supporting Information File 32: CIF of bisborane complex B. Acknowledgements Funding by the BMEL (Federal Ministry of Food and Agriculture) within the project FOREST (22403116) and by the CMBlu AG

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• ] starting from 7-diethylaminocoumarin-3-aldehyde (26) and 5-aminopyrazole derivatives 16 (Scheme 4). The structure of the synthesized compounds was confirmed by X-ray crystallography, 1H and 13C NMR and HRMS studies. The relationships between the structures and chemical properties of these compounds were

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• was characterized by X-ray crystallography. Aryl iodides, which contained nitrile, ketone, aldehyde, ester, methyl, phenyl groups, etc., were successfully reacted with this trifluoromethylation reagent to give the corresponding products in moderate to high yields. Also, a broad spectrum of heteroaryl

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• led to the development of a large number of techniques for such investigations. Among the most significant ones are NMR [1] and X-ray crystallography [2]. Both techniques offer a high structure resolution and NMR can also provide information on dynamics. However, there are occasions where NMR and X

• -ray crystallography suffer from drawbacks: the sample amount requirement and biomolecular size restriction for NMR and the difficulties in obtaining crystals and the obvious lack of solution dynamics for X-ray crystallography. An important method for biomolecular structure and dynamics investigations

• Å, respectively [25]. This is in contrast to previously reported values showing slight increases in helical twist and rise measured, for example, by sedimentation [77], gel electrophoresis [78][79], X-ray crystallography [74] and magnetic tweezers [75]. In our investigation we modeled the general

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• stereochemistry of 12 was confirmed by X-ray crystallography of the 4-bromophenyl ester derivative 13. Alcohol 12 was activated as the tosyl ester at −20 °C, and then immediately displaced by LiAlD4 [17], inverting the stereocenter to afford the (S)-diarylmethane 10 isotopomer in 18% ee. 2H{1H} NMR in a PBLG

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• and ethyl esters were determined by X-ray crystallography [19]. The X-ray structure of the Pt(II) chelate of tetramethyl 2,6,9-trioxabicyclo[3.3.1]nona-3,7-diene obtained from tris-acetylacetonato platinum(II) was determined previously [22][23], and the separation of the enantiomers of the free ligand

• was achieved by fractional crystallization [24]. Chirality of the bisdioxine dicarbaldehyde, 2,6,9-trioxabicyclo[3.3.l]nona-3,7-diene-4,8-dicarbaldehyde, obtained by extrusion of water from triformylmethane, has also been demonstrated [25], and X-ray crystallography confirmed the structure of this

• , urethanes and isocyanates point inward (Scheme 9). This observation was confirmed by X-ray crystallography as well as calculations at the B3LYP/6-31G** level [38][39]. The tert-butyl groups provide steric protection to the exo sides of the molecules, making the diisocyanate stable at ordinary temperatures

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• reactions. The scope of the reaction was successfully expanded to include primary, secondary, and tertiary alcohol nucleophiles. Through X-ray crystallography, the stereochemistry of the product was determined which confirmed an SN2-like mechanism to form the ring-opened product. Keywords: acid catalysis

• most cases, the starting material was completely consumed, the yields of these ring-opening reactions were only moderate (26–61%). This may be due to the decomposition or polymerization of the cyclopropanated 3-aza-2-oxabicyclic alkene under the reaction conditions. Through X-ray crystallography [20

• of the reaction was successfully expanded to include primary, secondary, and tertiary alcohol nucleophiles. Through X-ray crystallography, the stereochemistry of the product was determined which confirmed an SN2-like mechanism to form the ring-opened product. Further investigation of the ring-opening

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• photoaddition products 3a and 3b were unambiguously confirmed by X-ray crystallography (Figure 2). In the solid state, molecules of both compounds undergo hydrogen bonding between the newly formed hydroxy group and the intact carbonyl group, resulting in a one-dimensional network (see Supporting Information

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

• pure compounds, while the heterogeneity observed at 45 °C was connected to the presence of different rotameric states. To confirm the determined positions of the N-adamantane substitutions, compounds 15a and 15b were studied by X-ray crystallography. Suitable crystals of 15a and 15b were obtained by

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

• Information File 1. Similar to our study, Sirakanyan et al. [46] presented the synthesis and structure of condensed triazolo- and tetrazolopyrimidines, wherein, in DMSO-d6, tetrazolo-azidopyrimidines were in equilibrium. However, the structure confirmed by X-ray crystallography was the tetrazole form, which

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• of axial ligand substituted subphthalocyanine hybrid dyes. Energy transfer between subphthalocyanine units. Structure of phthalocyanine and subphthalocyanine benzene-fused homodimers. X-ray crystallography of Pc-subPc (left) and UV–vis spectra of benzene-fused dimers. Synthesis of trifluoroethoxy

Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• (sharp singlet) could be assigned to BF4− as the most common hydrolysis byproduct by comparison with HBF4 in DMSO-d6. X-ray crystallography Compounds 2f, 2g and 2h were also characterized by X-ray diffraction methods. Crystals suitable for analysis were grown by slow diffusion of n-hexane into CH2Cl2

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

• ][74] and chromocenes [75], to form one-to-one charge-transfer salts 100 (Scheme 31), which are molecular magnets. Their physical properties depend on the size of the alkyl groups of the ester function [73]. Some chromocene complexes with E-1a,b were studied by means of X-ray crystallography [74][76

Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• diastereomers (see Scheme 3 for atom numbering). This configuration was unambiguously confirmed by a single crystal X-ray crystallography of compound 12ab (CCDC 1546062) shown in Figure 1. Puzzled by this unexpected reactivity, we reasoned that the enolate moiety can be activated towards the desired

• , which ultimately could help us to redirect the course of the reaction towards formation of spirolactones of type 20. To evaluate this idea, we prepared ketazinones 22 (crystal structure of ketazinone 22a was confirmed by X-ray crystallography (CCDC 1546065, Figure 3)), derived from benzophenone and

Preparation of imidazo[1,2-a]-N-heterocyclic derivatives with gem-difluorinated side chains

• Layal Hariss,
• Kamal Bou Hadir,
• Mirvat El-Masri,
• Thierry Roisnel,
• René Grée and
• Ali Hachem

Beilstein J. Org. Chem. 2017, 13, 2115–2121, doi:10.3762/bjoc.13.208

• 7e by X-ray crystallography analysis. Retrosynthetic scheme for the preparation of our target molecules A. Synthesis of enones 6 with a gem-difluoroalkyl side chain. Synthesis of 7a. One-pot synthesis of 7a. Synthesis of enones 6a–e. Preparation of different imidazo[1,2-a]-N-heterocyclic derivatives

Complexation of molecular clips containing fragments of diphenylglycoluril and benzocrown ethers with paraquat and its derivatives

• Leonid S. Kikot',
• Catherine Yu. Kulygina,
• Alexander Yu. Lyapunov,
• Svetlana V. Shishkina,
• Roman I. Zubatyuk,
• Tatiana Yu. Bogaschenko and
• Tatiana I. Kirichenko

Beilstein J. Org. Chem. 2017, 13, 2056–2067, doi:10.3762/bjoc.13.203

• chain – to that of the complexes of the clips 3–5 with paraquat (7). The data obtained show that the clips 4 and 5 are maximum pre-organized to form a 1:1 complex with paraquat compared to other clips with benzocrown ether moieties. X-ray crystallography The structures of the complexes of clips 2, 3 and

• 5 with paraquat (7) have been studied by X-ray crystallography. All these clips form inclusion complexes with a 1:1 ratio where the paraquat molecule is located within the pseudo-cavity formed by two crown ether fragments (Figure 6). The complexes are stabilized by π–π intermolecular stacking

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

• (+) and gg(−) conformations around the 1,2-diacyl moiety (Figure 1). From X-ray crystallography data, a common structure in which the 1,2-diacyl chains are aligned in parallel is observed, which adopts either the gt(+) or gg(−) conformer [7][10][12]. An analogous conformation has been reportedly observed

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

• -regulation of Bim. Furthermore, the suggested interaction of mycolactone A/B with FKBP12 is supported by the protective effects of an excess of FK506 against mycolactone-induced apoptosis. However, further experimental validation of the mycolactone-FKBP12 interaction, e.g., by SPR, NMR or X-ray

• crystallography, would be highly appreciable. Finally, we also demonstrated the key role of mycolactone-triggered Bim-mediated apoptosis in vivo. To this end, the food pads of wild-type (WT) and homozygous Bim and Fas knockout mice (Bim−/− and Fas−/−) were infected with M. ulcerans. Intriguingly, WT and Fas

Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

• Spyros D. Chatziefthimiou,
• Mario Inclán,
• Petros Giastas,
• Athanasios Papakyriakou,
• Konstantina Yannakopoulou and
• Irene M. Mavridis

Beilstein J. Org. Chem. 2017, 13, 1572–1582, doi:10.3762/bjoc.13.157

• constants, K, of the L- to the D-enantiomer) shows an increasing order (1.04, 1.1 and 1.34, respectively). X-ray crystallography, on the other hand, can improve our understanding of chiral recognition by CDs at the atomic level by providing insight into the interactions and the fit of the guest in the

• diagrams [15], NMR spectroscopy [16] and electrochemical methods [17], as well as by X-ray crystallography [18]. Detailed structures of β-CD with L- and D-N-acetylphenylalanine (NAcPhe) grown separately [18] has shown that although the two complexes are isomorphous (same space group, very similar unit cell

• percentage cannot be excluded. X-ray crystallography studies In the crystalline state, the structure of the inclusion complex of L-NAcTrp in β-CD comprises dimers. The asymmetric unit of the complex contains two crystallographically independent β-CD hosts (A and B) forming a dimer (Figure 2), in which two

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• [1][28] but never isolated) was characterized by means of 1H and 13C NMR spectroscopy as well as X-ray crystallography. The isolation, for the first time, of the Mannich-type adduct 13 between HPA and an imine clearly attests to the viability of mechanistic pathway (b) shown in Scheme 3. When left at

• spectrometry and X-ray crystallography and certain regularities in the NMR behavior have been established, leading a set of rules for stereochemical assignment based on the NMR data. A Mannich-type adduct between HPA and an imine (previously only postulated as a crucial intermediate en route to CCR products

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• nature of the target product and concomitant impurities. In addition to the data of 1H and 13C NMR and elemental analysis, the structure of nitro-substituted ICZs 9 and 10 has been confirmed unequivocally by X-ray crystallography analysis of derivatives 9b and 10b (Figure 4). Taking into account that

• performed by using the Suzuki–Miyaura cross-coupling reaction with phenylboronic acid under Pd catalysis (Scheme 5). The location of the formyl group and bromine atoms in ICZ derivatives 12 and 13 has been established by X-ray crystallography analysis, performed for single crystals of 12b and 13b (Figure 5

• desired product in 88% yield. At the same time, in the experiment with fuming nitric acid (5 equiv), used instead of acetyl nitrate (Table 1, entry 5), we have obtained a mixture of compound 2a and byproducts again. The molecular structure of compound 2a has been proved unequivocally by X-ray

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

• , anticancer, anti-HIV, antithrombotic, analgesic and antidiabetic [1][2][3]. Substitution on C(3) of quinoxalin-2(1H)-ones 1 by substituents that possess a carbonyl group in a β side chain position 2, 3 significantly alters their chemical properties as suggested by 1H NMR, IR spectra and X-ray crystallography

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• hydrolases; glycosyl transferases; kinetic crystallography; lectins; polysaccharides; powder diffraction; small-angle X-ray scattering; starch; synchrotron radiation; transporters; X-ray crystallography; Introduction Over the last decade, glycoscience has greatly benefited from the development of structural

• recognition with the elucidation of glycosyl hydrolases mechanism by X-ray crystallography, but the scope of applications in glycobiology is much broader: it encompasses the range of glycan containing (macro)-molecules and their conjugates. The present article reviews the application of synchrotron radiation

• thrombin and antithrombin at 2.5 Å resolution. For the time being, this is one of the largest oligosaccharide structures ever established throughout macromolecular X-ray crystallography (Figure 12) [59]. Transporters: Soluble sugars serve many purposes in complex organisms. Their cellular exchange relies

G-Protein coupled receptors: answers from simulations

• Timothy Clark

Beilstein J. Org. Chem. 2017, 13, 1071–1078, doi:10.3762/bjoc.13.106

• , so that the low number of structures being published represents the output of a major worldwide research effort to obtain structures for receptors that unfortunately require considerable ingenuity (and luck) to obtain suitable crystals for X-ray crystallography [6]. Not only has the paucity of