Fluorinated cyclohexanes: Synthesis of amine building blocks of the all-cis 2,3,5,6-tetrafluorocyclohexylamine motif

• Tetiana Bykova,
• Nawaf Al-Maharik,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2017, 13, 728–733, doi:10.3762/bjoc.13.72

• chromatography. Finally fluorination of 10b and 10c in separate reactions with Et3N·3HF at 120 °C furnished nitrile 11b (51% yield) and 11c (31% yield) respectively. The structure and stereochemistry of both products were unambiguously confirmed by X-ray structure analysis (Scheme 3). Reduction of 11b with

• nickel boride delivered amine 5b in 65% yield as a crystalline solid and an analogous reduction of 11c generated the racemic amine 5c as a colourless liquid. The structure of 11b was confirmed by X-ray structure analysis (Scheme 3). Amines 5a and 5b were reacted with terephthaloyl chloride as a means of

• . However suitable crystals were obtained from acetone/acetonitrile for X-ray structure analysis. The X-ray structures of 13, 14 and 15 are illustrated in Figure 2. It was assumed that the facial polarity of the tetrafluorocyclohexane rings would be apparent in the molecular ordering in the solid state

Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21–50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13C NMR data

Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• was possible by comparison of the experimental and DFT-calculated VCD spectra (Figure 5) with a satisfactory ESI value of 80%. Eventually, the absolute configuration of (S)-3 could be unambiguously determined by X-ray structure analysis of a single crystal, which was obtained by slow cooling of a hot

Synthesis, dynamic NMR characterization and XRD studies of novel N,N’-substituted piperazines for bioorthogonal labeling

• Constantin Mamat,
• Marc Pretze,
• Matthew Gott and
• Martin Köckerling

Beilstein J. Org. Chem. 2016, 12, 2478–2489, doi:10.3762/bjoc.12.242

• from coalescence temperatures Tc which were determined from dynamic 1H NMR measurements. The formation of conformers resulting from the partial double bond was additionally determined and verified using single crystal X-ray structure analysis. The second coalescence point is caused by the reduced

• showed a Tc of 248 K with a ΔG# of 11.1 kJ/mol [23] whereas piperidine shows a higher ΔG# of 42.3 and N-methylpiperidine a ΔG# = 49.8 kJ/mol [21][28]. X-ray structure analyses of 3a and 4b Single crystals of 3a and 4b were obtained and their molecular structures determined using single crystal X-ray

• structure analysis. Crystals of 3a have monoclinic symmetry of the space group C2/c. Crystals of 4b have monoclinic symmetry of the space group P21/n. The C14–C15 distance of 1.188(1) Å and the C13–C14–C15 angle of 178.2(1)° clearly indicate this group to be an alkyne residue, thus enabling the use of the

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

• configuration of compound 2 was unambiguously determined by X-ray structure analysis and ECD calculation. Moreover, the absolute configurations of compounds 3–5 were assigned by comparison of their ECD spectra with isocoumarins described in the literature. Asperisocoumarins C and D (3 and 4) were fully

Rapid regio- and multi-coupling reactivity of 2,3-dibromobenzofurans with atom-economic triarylbismuths under palladium catalysis

• Maddali L. N. Rao,
• Jalindar B. Talode and
• Venneti N. Murty

Beilstein J. Org. Chem. 2016, 12, 2065–2076, doi:10.3762/bjoc.12.195

• minor amounts. Evidently, this generalization of bis-coupling reactivity was proved to be operationally simple with high reactivity and yields involving 2 h short reaction time and with sub-stoichiometric loadings of the bismuth reagent. Incidentally, we could also obtain the X-ray structure analysis

Potent triazine-based dehydrocondensing reagents substituted by an amido group

• Munetaka Kunishima,
• Daiki Kato,
• Nobu Kimura,
• Masanori Kitamura,
• Kohei Yamada and
• Kazuhito Hioki

Beilstein J. Org. Chem. 2016, 12, 1897–1903, doi:10.3762/bjoc.12.179

• intermediate 7 (Scheme 2). Single-crystal X-ray structure analysis, two-dimensional NMR spectroscopy, or derivatization of I–VI was performed to unambiguously determine their structures, i.e., whether the N- or O-substituted derivative was prepared from the amido anion (Supporting Information File 1). To

• esterification of 3-phenylpropanoic acid (1a) in neat MeOH were studied (Figure 3). Although X was shown to exist as a dihydrate by elemental analysis and single-crystal X-ray structure analysis, the yield of methyl 3-phenylpropanoate was quantitative. The rate of esterification with X was faster than that with

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• heptafulvalene) as well as the very low N–C–N angle by X-ray structure analysis [41]. Weiss proposed this carbene to have a “built-in umpolung” [39] ability which means that there could be a participation of the dicationic bisylidene resonance form as it is usually described for carbodiphosphoranes [49] and

Dinuclear thiazolylidene copper complex as highly active catalyst for azid–alkyne cycloadditions

• Anne L. Schöffler,
• Ata Makarem,
• Frank Rominger and
• Bernd F. Straub

Beilstein J. Org. Chem. 2016, 12, 1566–1572, doi:10.3762/bjoc.12.151

• vacuo to give the colourless product 1b (1.50 g, 2.75 mmol, 76%). Single crystals of salt 1b that were suitable for an X-ray structure analysis were obtained from acetone/diethyl ether. 1H NMR (400.33 MHz, acetone-d6, 295.0 K) δ 9.88 (s, 2H, NCHS), 5.42 (s, 4H, CH2), 2.68 (s, 6H, NCCH3), 2.66 (s, 6H

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• : 37717). In addition, the structure was confirmed by the alternative synthesis of 2a through the heterocyclization of 2-nitrobenzoic acid [28][29] and X-ray structure analysis [33]. The authors observed that the yields of both 2a and 3a increased with increasing amount of water as nucleophilic solvent in

Selectively fluorinated cyclohexane building blocks: Derivatives of carbonylated all-cis-3-phenyl-1,2,4,5-tetrafluorocyclohexane

• Mohammed Salah Ayoup,
• David B. Cordes,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 2671–2676, doi:10.3762/bjoc.11.287

• ratio, respectively, which could be separated by column chromatography. The reaction is illustrated in Scheme 2. The structure of aldehyde 15 was confirmed by X-ray structure analysis and is shown in Figure 2. Transformations of benzaldehyde 15 were explored. For example McMurry coupling [12] of 15 gave

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• , absorption and fluorescence studies. The quantum chemical research (V. I. Minkin) was supported by the internal grant of the Southern Federal University (project No 213.01-2014/005ВГ). V. V. Tkachev and S. M. Aldoshin would like to acknowledge the financial support of X-ray structure analysis from Programs

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• refrigerator for longer periods of time without decomposition. Slow evaporation of the solvent of a chloroform solution provided single crystals of 13 that were suitable for X-ray structure analysis. The resulting structure is shown in Figure 1. Compound 13 crystallizes with two independent but closely similar

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• (2R,1'R,2'S)-26b were determined by a single crystal X-ray structure analysis (see Figure 3 and Supporting Information File 1) [28]. The isolated nickel complexes 26a–c were decomposed by treatment with refluxing aqueous methanolic hydrogen chloride to give, after ion-exchange chromatography, the

• by experimental tests [36]. The initially formed main product (R,R,R)-28 in the aldol reaction of acetaldehyde with 10 had the same configuration at C-2 as the proline unit in 10. The absolute configuration of this nickel(II) complex was determined by a single crystal X-ray structure analysis (see

The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

• Sarah Bay,
• Gamall Makhloufi,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 1006–1016, doi:10.3762/bjoc.10.100

• large distances. Based on the starting geometry from the X-ray structure analysis of S(O)-1 the frontier molecular orbitals (FMO) of 1 were calculated on the DFT level of theory with the B3LYP functional and the Pople basis set 6-311G* (Figure 4) [83][84][85][86]. It is noticeable that the coefficient

• spectra of 8 and 10 unambiguously supports the structural assignment and that isomeric mixtures due to restricted amide-bond rotation can be excluded. Besides mass spectrometry and combustion analysis the structure of phenothiazine–anthraquinone dyads 8a–d was additionally supported by an X-ray structure

• analysis of the partially oxidized derivative of compound S(O)-1 (Figure 2) [75]. The phenothiazine and anthraquinone moieties are aligned by intramolecular π-stacking with an average distance of ~3.9 Å [76][77]. In the unit cell the R- and S-enantiomers of a single diastereomer (S-oxide) are arranged in

Use of activated enol ethers in the synthesis of pyrazoles: reactions with hydrazine and a study of pyrazole tautomerism

• Denisa Tarabová,
• Stanislava Šoralová,
• Martin Breza,
• Marek Fronc,
• Wolfgang Holzer and
• Viktor Milata

Beilstein J. Org. Chem. 2014, 10, 752–760, doi:10.3762/bjoc.10.70

• ). The structure of 6a was confirmed by spectroscopic analysis, elemental analysis, and X-ray structure analysis (Figure 5). A sample of compound 6a was recrystallized by slow evaporation from chloroform. X-ray diffraction data (Supporting Information File 1, Tables S1–S5) were collected on an Oxford

Self-assembly of metallosupramolecular rhombi from chiral concave 9,9’-spirobifluorene-derived bis(pyridine) ligands

• Rainer Hovorka,
• Sophie Hytteballe,
• Torsten Piehler,
• Georg Meyer-Eppler,
• Filip Topić,
• Kari Rissanen,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2014, 10, 432–441, doi:10.3762/bjoc.10.40

• , in CD2Cl2 at 298 K). ESI mass spectrum (positive mode) of an 1:1:2 mixture of (R)-3, (S)-6, and [(dppp)Pt(OTf)2] in acetonitrile. Single crystal X-ray structure analysis of [(dppp)2Pd2{(R)-3}2][(dppp)2Pd2{(S)-3}2](OTf)8 obtained from a 1:1 mixture of (rac)-3 and [(dppp)Pd(OTf)2]. (Counterions and

Intermediates in monensin biosynthesis: A late step in biosynthesis of the polyether ionophore monensin is crucial for the integrity of cation binding

• Wolfgang Hüttel,
• Jonathan B. Spencer and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 361–368, doi:10.3762/bjoc.10.34

• monensin derivatives in excellent yields (ΔmonD: 1.13 g L−1 dehydroxymonensin; ΔmonE: 0.50 g L−1 demethylmonensin; and double mutant ΔmonDΔmonE: 0.34 g L−1 dehydroxydemethylmonensin). Single crystals were obtained from purified fractions of dehydroxymonensin and demethylmonensin. X-ray structure analysis

The regioselective synthesis of spirooxindolo pyrrolidines and pyrrolizidines via three-component reactions of acrylamides and aroylacrylic acids with isatins and α-amino acids

• Tatyana L. Pavlovskaya,
• Fedor G. Yaremenko,
• Victoria V. Lipson,
• Svetlana V. Shishkina,
• Oleg V. Shishkin,
• Vladimir I. Musatov and
• Alexander S. Karpenko

Beilstein J. Org. Chem. 2014, 10, 117–126, doi:10.3762/bjoc.10.8

• obtained by the above method were characterized by mass spectrometry, 1H and 13C NMR, and elemental analyses. The regiochemical outcome of the cycloaddition was unambiguously confirmed by NOE experiments in 1H NMR as well as later by a single crystal X-ray structure analysis of the cycloadduct 4a. The 1H

The difluoromethylene (CF₂) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF₂ groups

• Yi Wang,
• Ricardo Callejo,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2014, 10, 18–25, doi:10.3762/bjoc.10.4

• °C) with a melting point very similar to nonadecane (32–35 °C). A suitable crystal was subject to X-ray structure analysis and the resultant structure is shown in Figure 7. It is clear that the alkyl chain of 27 is extended in a similar conformation to that found in palmitic acid 6c and we conclude

Crystal design using multipolar electrostatic interactions: A concept study for organic electronics

• Peer Kirsch,
• Qiong Tong and
• Harald Untenecker

Beilstein J. Org. Chem. 2013, 9, 2367–2373, doi:10.3762/bjoc.9.272

• solubility of 1 in all usual organic solvents, small crystals suitable for X-ray structure analysis were obtained by very slow room temperature crystallization from THF. The quality of the crystals was borderline poor, but it was possible to gather data for a sufficiently accurate picture of the packing

• 412.0358798; found, 412.03517; Single crystals for the X-ray structure analysis were obtained by slow crystallization from THF. Crystal structure data for 1 (C22H8F4O4): crystal size 0.0909 × 0.045 × 0.0297 mm, triclinic, P−1, a = 6.0570(9) Å, b = 7.6382(12) Å, c = 8.829(3) Å, α = 94.98(2)°, β = 97.72(2)°, γ

Synthesis and characterization of novel bioactive 1,2,4-oxadiazole natural product analogs bearing the N-phenylmaleimide and N-phenylsuccinimide moieties

• Catalin V. Maftei,
• Elena Fodor,
• Peter G. Jones,
• M. Heiko Franz,
• Gerhard Kelter,
• Heiner Fiebig and
• Ion Neda

Beilstein J. Org. Chem. 2013, 9, 2202–2215, doi:10.3762/bjoc.9.259

• compounds 4 and 5 were also confirmed by X-ray structure analysis (Figure 7, Figure 8 and Figure 9). In compound 4 the oxazoline and phenyl rings are approximately coplanar (6°), but the pyrrolidine ring is rotated by 52° with respect to the phenyl ring. The main packing interaction is an offset stacking

• compound 6 was also confirmed by X-ray structure analysis (Figure 10 and Figure 11). In compound 6 the interplanar angle is 11°; the intramolecular hydrogen bond is almost symmetrical (O4–H04 1.03(3), H04···O2 1.47(3)) Å. The molecules are linked to form layers perpendicular to the hexagonal c axis by one

• NMR) and good to high yields (75–96%). The structural assignments were corroborated by X-ray structure analysis. Experimental General All reagents were purchased from commercial sources (Sigma-Aldrich or Acros) and used without further purification. Solvents were of analytical grade. 1H and 13C NMR

Isolation and X-ray characterization of palladium–N complexes in the guanylation of aromatic amines. Mechanistic implications

• Abdessamad Grirrane,
• Hermenegildo Garcia and
• Eleuterio Álvarez

Beilstein J. Org. Chem. 2013, 9, 1455–1462, doi:10.3762/bjoc.9.165

• and GC–MS spectra for new compounds. Supporting Information File 380: X-Ray structure analysis data for 4a (CCDC-931786, 4b (CCDC-931787), 4c (CCDC-931788) and 5a (CCDC-931789) are given. These data can also be obtained free of charge from The Cambridge Crystallographic Data Centre via http

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• additional charge at physiological pH. Thus, the parent methylidynetrisphosphonic acid and its fluoro- and chloro-substituted derivatives have at least one more negative charge than pyrophosphate at pH 7 (Table 1) [7][27]. X-ray structure analysis of trisphosphonic salt [FC(PO3H)3]3− 3Na+ supported its

Design and synthesis of a photoswitchable guanidine catalyst

• Philipp Viehmann and
• Stefan Hecht

Beilstein J. Org. Chem. 2012, 8, 1825–1830, doi:10.3762/bjoc.8.209

• 2E. The therefore necessary urea 4 can be obtained from the addition of pyrrolidine to phenylisocyanate (3). The structure of guanidine 2E was proven by NMR spectroscopy, HRMS, as well as by single-crystal X-ray structure analysis (Figure 1). To our knowledge, this is the first example of an X-ray

• catalytic inactivity of guanidine 2E is indeed caused by the guanidine core itself. Besides the previously mentioned basicity issue, a possible reason for this behavior may be discerned from the single-crystal X-ray structure analysis of guanidine 2E. It can be seen that, in contrast to the supposed