Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids

• Maximilian Koy,
• Hagen J. Altmann,
• Benjamin Autenrieth,
• Wolfgang Frey and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178

• = mesitylene). Single crystal X-ray structure of Ru-2. Co-solvent and disordered triflates have been omitted for clarity. Monomers used for biphasic ROMP reactions. Improved synthesis of Ru-1 and quarternization with methyl trifluoromethanesulfonate to Ru-2. Recycling of Ru-2 for continuous ROMP reactions

Structure and conformational analysis of spiroketals from 6-O-methyl-9(E)-hydroxyiminoerythronolide A

• Ana Čikoš,
• Irena Ćaleta,
• Dinko Žiher,
• Mark B. Vine,
• Ivaylo J. Elenkov,
• Marko Dukši,
• Dubravka Gembarovski,
• Marina Ilijaš,
• Snježana Dragojević,
• Ivica Malnar and
• Sulejman Alihodžić

Beilstein J. Org. Chem. 2015, 11, 1447–1457, doi:10.3762/bjoc.11.157

• energy constraints to the X-ray structure followed by unconstrained minimization. Significant conformational changes were not expected due to the rigidity of the tricyclic system. A low energy conformation of 2 is presented in Figure 1. Analogous to pyranoside conformations, the highly substituted

• single crystal X-ray structure of erythronolide A anhydro derivative (CSDC refcode: ERYTHR [55]) and minimized with constraints of 1000 kcal on all atoms with known X-ray coordinates. The model of 3 was generated from the model of compound 2. The model of 4 was obtained by molecular modelling with NMR

Design and synthesis of fused polycycles via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Ongolu Ravikumar

Beilstein J. Org. Chem. 2015, 11, 1259–1264, doi:10.3762/bjoc.11.140

• with allylmagnesium bromide to produce 1,2-addition product 4. A molecular model of compound 3 reveals that its exo-face is more accessible for Grignard addition than the endo-face. Also, the X-ray structure of compound 5 indicates the stereostructure of 4. Further, the diol 4 was treated with four

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• hydrogenation conditions (Pt, 100 °C, acetic acid). We assume that the spatial shielding of the double bond, as indicated by the X-ray structure, is responsible for this. Furthermore, we were also unable to epoxidize or brominate 4. The next higher vinylog of 3, the triene 7, is much more easily hydrogenated

Trifluoromethyl-substituted tetrathiafulvalenes

• Olivier Jeannin,
• Frédéric Barrière and
• Marc Fourmigué

Beilstein J. Org. Chem. 2015, 11, 647–658, doi:10.3762/bjoc.11.73

• strong −I inductive effect. Among the nine possible combinations 1 and 2 described above (Scheme 2), the unsymmetrically disubstituted 2ab and 2ac have not been reported to date. We describe here the syntheses of 2ac from 2bc and the single-crystal X-ray structure determinations of both 2ac and 2bc

TTFs nonsymmetrically fused with alkylthiophenic moieties

• Rafaela A. L. Silva,
• Bruno J. C. Vieira,
• Marta M. Andrade,
• Isabel C. Santos,
• Sandra Rabaça,
• Dulce Belo and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 628–637, doi:10.3762/bjoc.11.71

• /AgCl, typical of TTF donors at E11/2 = 279 V and E21/2 = 680 V for 1 and E11/2 = 304 V and E21/2 = 716 V in the case of 2. The single-crystal X-ray structure of 1 and of a charge transfer salt of 2, (α-mtdt)[Au(mnt)2] (3), are reported. Keywords: cyclic voltammetry; single-crystal X-ray diffraction

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• ; this was confirmed by an X-ray structure for 2. These compounds also had a significantly higher solubility in organic solvents relative to the parent indigo starting material. Although indigo starting material also remained at the end of the reaction, it could be readily separated on the basis of

The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50

• ) displays no formal crystallographic inversion symmetry, but is approximately inversion-symmetric (rmsd 0.02 Å). Again, we have reported the structure of the corresponding pseudo-gem isomer [20]. A search of the Cambridge database [31] revealed, perhaps surprisingly, that there are only two other X-ray

• structure determinations of organic isocyanates with the NCO group bonded to a phenyl ring. The dimensions of the isocyanate group observed for 28 [Cring–N 1.408(2), 1.419(2), N–C 1.194(3), 1.192(3), C–O 1.173(2), 1.174(2) Å; Cring–N–O 140.0(2), 136.9(2), N–C–O 172.6(2), 172.5(2)°] are closely similar to

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

• by the usual spectroscopic methods was straightforward and the obtained spectra agreed with the reported data [28]. The assignment was corroborated by a single-crystal X-ray structure determination (Figure 6); single crystals were obtained by slow evaporation of a pentane solution. The molecule of 30

An unusually stable chlorophosphite: What makes BIFOP–Cl so robust against hydrolysis?

• Roberto Blanco Trillo,
• Jörg M. Neudörfl and
• Bernd Goldfuss

Beilstein J. Org. Chem. 2015, 11, 313–322, doi:10.3762/bjoc.11.36

• backbones provoke different reactivities due to tighter encapsulation of the P–Cl unit by the fenchane moieties in BIFOP–Cl (1) relative to O–BIFOP–Cl (3). Geometries bases on the X-ray structure of BIFOP–Cla and O–BIFOP–Cl. Computed relative energies (Erel, kcal/mol) for the reaction of 2, 4 or 8 with

Synthesis of dinucleoside acylphosphonites by phosphonodiamidite chemistry and investigation of phosphorus epimerization

• William H. Hersh

Beilstein J. Org. Chem. 2015, 11, 184–191, doi:10.3762/bjoc.11.19

• barriers. Supporting Information Supporting Information contains the experimental procedures, characterization of new compounds, copies of 1H, 13C and 31P NMR spectra, IR spectra, details of the X-ray structure determination, and details of the DFT calculations. Supporting Information File 189

Molecular cleft or tweezer compounds derived from trioxabicyclo[3.3.1]nonadiene diisocyanate and diacid dichloride

• Gert Kollenz,
• Ralf Smounig,
• Ferdinand Belaj,
• David Kvaskoff and
• Curt Wentrup

Beilstein J. Org. Chem. 2015, 11, 1–8, doi:10.3762/bjoc.11.1

• for 7b (11–15%) compared to 6b (3–9%). Conclusion X-ray structure determinations confirmed the endo,endo structures of the bisurea 4 and biscarbamate 5, which in turn confirm the endo,endo structure of the diisocyanate 1. Bis-crown ether diamide derivatives 7 also feature endo,endo structures as

Inclusion of trans-resveratrol in methylated cyclodextrins: synthesis and solid-state structures

• Lee Trollope,
• Dyanne L. Cruickshank,
• Terence Noonan,
• Susan A. Bourne,
• Milena Sorrenti,
• Laura Catenacci and
• Mino R. Caira

Beilstein J. Org. Chem. 2014, 10, 3136–3151, doi:10.3762/bjoc.10.331

• inclusion complexes [15], the one to which this complex belongs has relatively few members. The third complex whose X-ray structure is described here has the formula DMB·RSV·4.0H2O, the host molecule DMB being 2,6-dimethylated β-CD and consequently having properties that are intermediate between those of

(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

Phosphinocyclodextrins as confining units for catalytic metal centres. Applications to carbon–carbon bond forming reactions

• Matthieu Jouffroy,
• Rafael Gramage-Doria,
• David Sémeril,
• Dominique Armspach,
• Dominique Matt,
• Werner Oberhauser and
• Loïc Toupet

Beilstein J. Org. Chem. 2014, 10, 2388–2405, doi:10.3762/bjoc.10.249

• Table 3 and Table 4 correspond to the mean value from two catalytic tests. CD-based mono- and diphosphines with inward-pointing phosphorus atoms. X-ray structure of aqua palladium complex 5 [44] (top: side view; bottom: view from the primary face). The cavity contains two non-coordinated water molecules

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• X-ray structure determination and Prof. A. C. Filippou for providing X-ray infrastructure.

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210

• were obtained by recrystallization from pentane/chloroform to allow their X-ray structure determination in the solid state. The results are shown in Figure 2. The molecule displays crystallographic inversion symmetry (which precludes the use of standard cyclophane numbering to some extent). It shows

Structure/affinity studies in the bicyclo-DNA series: Synthesis and properties of oligonucleotides containing bc^en-T and iso-tricyclo-T nucleosides

• Branislav Dugovic,
• Michael Wagner and
• Christian J. Leumann

Beilstein J. Org. Chem. 2014, 10, 1840–1847, doi:10.3762/bjoc.10.194

• the context of nucleic acid duplex conformation. Quite interestingly, the original tc-T nucleoside [34], for which we solved the X-ray structure here for the first time (Figure 2), shows considerable conformational variability in the furanose part. The asymmetric unit contains two independent

• . Chemical structures and carbon numbering scheme of tricyclo(tc)-DNA (top, left), bicyclo(bc)-DNA (top, right) and the newly synthesized iso-tricyclo(iso-tc)-DNA (bottom, left) and bicyclo-en(bcen)-DNA (bottom, right). X-ray structure of top row: nucleosides 8β (left), 11β (center) and overlay of both

An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism

• Carla I. Nieto,
• Pilar Cabildo,
• M. Ángeles García,
• Rosa M. Claramunt,
• Ibon Alkorta and
• José Elguero

Beilstein J. Org. Chem. 2014, 10, 1620–1629, doi:10.3762/bjoc.10.168

• remaining protons; iii) a series of 2D experiments assign the CH carbons (HMQC) as well as the quaternary carbons C3a and C7a (HMBC). In the case of 3 all signals are considerably split in the solid state (Figure 4). The X-ray structure of compound 3 is known and reported in the Cambridge Structural

• . 1) to 0.80 (eq. 2). The use of the monomer or the central part of the trimer has no influence. The worse point is H7 of 4 that appears at 7.40 ppm and fitted with eq. 2 has a value of 7.14 ppm. The origin of this discrepancy is that the theoretical conformation corresponding to the X-ray structure

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones

• Jubi John,
• Eliza Târcoveanu,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150

• the usual spectroscopic methods (see Supporting Information File 1) and also by X-ray structure determination [43] for furanones 7 (product formed by the reaction of 1b with 2b) and 10 (product formed by the reaction of 1d with 2a) (Figure 3). We believe that the mechanism of the present furanone

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

• Friedrich Malberg,
• Jan Gerit Brandenburg,
• Werner Reckien,
• Oldamur Hollóczki,
• Stefan Grimme and
• Barbara Kirchner

Beilstein J. Org. Chem. 2014, 10, 1299–1307, doi:10.3762/bjoc.10.131

• experimental X-ray structure, see Table 1. The unit cell volume (Vol) is smaller than the experimental value by only 1.7%. Typical thermal cell expansions (from calculated 0 K to measured 100 K) are 2–3%. A recent study showed that PBE-D3 (with a large basis set) overestimates molecular sizes by approximately

• angles differ by less than 0.3° from the X-ray structure. Because the molecular structure is rather flexible, we observe interesting crystal packing effects. We compared the highlighted intramolecular distances and angles from experiment and theory in Figure 2. As a result, we exemplified the influence

• the Hammett σ parameters. The values are given in Table 1. Black curves: DB and red curves: SB. The solid lines are fits to all energies of the para-substitution only, the dotted lines are linear regressions to all interaction energies. Comparison of the X-ray structure of the rotaxane with the

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

• Gadi Ranjith Kumar,
• Yalla Kiran Kumar,
• Ruchir Kant and
• Maddi Sridhar Reddy

Beilstein J. Org. Chem. 2014, 10, 1255–1260, doi:10.3762/bjoc.10.125

• the tentative intermediate 6. As expected, the reaction on 2a proceeded through a 6-membered cyclization to form 7 which underwent aromatization via elimination of acetic acid to produce 8. Product 8 exists in tautomerized form of 9 (vide infra, X-ray structure of 9j). In fact, an elegant synthesis of

• extracts were dried over Na2SO4, filtered and concentrated. The crude solid product was purified by column chromatography (silicagel, 20–30% EtOAc in hexanes) to get the pure product 9 (180 mg, 62% yield). X-ray Structure of 9j (CCDC number 971729). Synthesis of unsaturated amides via ketenimine formation

• : Analytical data. Supporting Information File 92: X-ray structure. Acknowledgements GRK and YKK thank CSIR for the PhD fellowships. We thank SAIF division CSIR-CDRI for the analytical support. We thank Dr. Tejender S. Thakur of Molecular and Structural Biology Division, CSIR-Central Drug Research Institute

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

• these novel donor–acceptor dyads. In addition, the X-ray structure of a phenothiazinyl–anthraquinone dyad supports short donor–acceptor distances by an intramolecular π-stacking conformation, an important assumption also implied in the calculations of the Gibbs energies according to the Weller

• 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

• 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

Allenylphosphine oxides as simple scaffolds for phosphinoylindoles and phosphinoylisocoumarins

• G. Gangadhararao,
• Ramesh Kotikalapudi,
• M. Nagarjuna Reddy and
• K. C. Kumara Swamy

Beilstein J. Org. Chem. 2014, 10, 996–1005, doi:10.3762/bjoc.10.99

• at δ ~ 4.78 (2J(P–H) = 18.0 Hz, PCH) which is absent in the latter set; the difference in the value of 1J(P–C) in the two sets is also consistent with the hybridization at the corresponding α-carbon (to phosphorus). Finally, the X-ray structure was determined for 20 (Figure 4). The above reaction is

• allenes 4b–d and 4h–j. We have also determined the X-ray structure of compound 33 (Figure 5) for final confirmation. It is possible that isocoumarins 30–35 are formed via the intermediates VIII–IX (Scheme 10) [40]. The phosphorus moiety of IX may then be cleaved as Ph2POOH to form the phosphorus-free

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• surpasses that in fullerene C60 (POAV angle = 11.6°, Figure 4). Moreover, the X-ray structure of circumtrindene (6) reveals that the carbon–carbon bonds around the 6-membered ring at the top of the dome are not equivalent. The bond lengths vary depending on their location (Figure 5), as is also observed in