The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes

• Yi Wang,
• Peer Kirsch,
• Tomas Lebl,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2012, 8, 1271–1278, doi:10.3762/bjoc.8.143

• by using a combination of 19F{1H} NMR spectroscopy, computational studies and, in the case of the threo isomer, X-ray structural analysis. In the lowest energy conformers for both diastereoisomers the vicinal C–F bonds are located corner/edge, rather than edge/edge. These structures avoid placing a C

Design of a novel tryptophan-rich membrane-active antimicrobial peptide from the membrane-proximal region of the HIV glycoprotein, gp41

• Evan F. Haney,
• Leonard T. Nguyen,
• David J. Schibli and
• Hans J. Vogel

Beilstein J. Org. Chem. 2012, 8, 1172–1184, doi:10.3762/bjoc.8.130

• resolved and not suitable for structural analysis (data not shown). Consequently, we chose to use a cosolvent mixture consisting of four parts deuterated chloroform, four parts deuterated methanol and one part water [19][20]. The 2D 1H NOESY spectra obtained in this solvent mixture were very well resolved

Synthesis of 2,6-disubstituted tetrahydroazulene derivatives

• Zakir Hussain,
• Henning Hopf,
• Khurshid Ayub and
• S. Holger Eichhorn

Beilstein J. Org. Chem. 2012, 8, 693–698, doi:10.3762/bjoc.8.77

• converted to 7 through thermal disrotatory electrocyclic ring opening and a base-catalyzed prototropic shift. The ester 7 underwent acid-catalyzed hydrolysis (formic acid) to afford 8 as a solid, which on recrystallization resulted in single crystals suitable for X-ray analysis (Scheme 2). The structural

• analysis of 8 revealed [22] an azulene framework that is partially hydrogenated to a cyclopentane subunit in places where molecules are slightly disordered in the lattice. These molecules represent the slightly torsionally distorted enantiomers of 8. At this stage we did not find any hydrogen atom at

Cyanoethylation of the glucans dextran and pullulan: Substitution pattern and formation of nanostructures and entrapment of magnetic nanoparticles

• Kathrin Fiege,
• Heinrich Lünsdorf,
• Sevil Atarijabarzadeh and
• Petra Mischnick

Beilstein J. Org. Chem. 2012, 8, 551–566, doi:10.3762/bjoc.8.63

• . Figure 3 shows the ATR–IR spectra for pullulan and the corresponding cyanoethyl ethers. 1H NMR spectroscopy is a versatile and fast method for qualitative and quantitative structural analysis. Figure 4 presents the 1H NMR spectra of cyanoethyldextrans CED-2 and CED-3 in comparison with the unmodified

Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes

• Henning Hopf,
• Vitaly Raev and
• Peter G. Jones

Beilstein J. Org. Chem. 2011, 7, 658–667, doi:10.3762/bjoc.7.78

• : paracyclophanes; photoadditions; photoisomerizations; proximity effects; topochemical reaction control; vinylcyclopropanes; X-ray structural analysis; Introduction Photodimerizations of crystalline aromatic or olefinic compounds are among the oldest known organic photoreactions. In this type of reaction the

• -conformation, which has been shown to be present as a conformer in the solid state by X-ray structural analysis does not photocyclize to 8. Moreover, syn,syn-7 is evidently too sterically hindered (by repulsion of the relevant hydrogen atoms as shown in Scheme 3) to be part of the conformational equilibrium

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

• Ryuji Hayashi,
• John B. Feltenberger,
• Andrew G. Lohse,
• Mary C. Walton and
• Richard P. Hsung

Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53

• . Supporting Information File 140: X-Ray structural analysis and information for compound 10b. Acknowledgements Authors thank NIH (GM066055) for financial support and Dr. Victor Young (University of Minnesota) for X-ray structural analysis.

Novel loop-like aromatic compounds: a further step on the road to nanobelts and nanotubes

• Venkataramana Rajuri,
• Dariush Ajami,
• Gaston R. Schaller,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2010, 6, No. 30, doi:10.3762/bjoc.6.30

• , hexafluorophosphate and hexafluoroantimonate, silver hexafluoroantimonate gave crystals with 2 on applying the diffusion method with dichloromethane/diethylether (Scheme 2). However, crystals of the corresponding silver complex with 3, suitable for X-ray structural analysis, could not be obtained. A number of

(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• inclusion complexes with aromatic guest molecules [54] and Cu(II) ion [56]. Additionally, van Well et al. have described a cyclization/cleavage strategy for solid phase synthesis of cyclic trimers and tetramers containing pyranoid δ-SAAs (Scheme 2) and reported their structural analysis from ROESY data in

The efficient synthesis of dibenzo[d,d′]benzo[1,2-b:4,3-b′]dithiophene and cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one

• Zhihua Wang,
• Sheng Zhu,
• Jianwu Shi and
• Hua Wang

Beilstein J. Org. Chem. 2009, 5, No. 55, doi:10.3762/bjoc.5.55

• of 1 from 3 is about 60%. When dilithiated 3 was treated with N,N-dimethylcarbamoyl chloride (DMC) at low temperature (−50 °C), a new helical ketone, cyclopenta[1,2-b:4,3-b′]bis(benzo[d]thiophen)-6-one (2), was obtained in 79% yield. X-ray structural analysis A single crystal of 1 was obtained by the

Structural studies on encapsulation of tetrahedral and octahedral anions by a protonated octaaminocryptand cage

• I. Ravikumar,
• P. S. Lakshminarayanan,
• E. Suresh and
• Pradyut Ghosh

Beilstein J. Org. Chem. 2009, 5, No. 41, doi:10.3762/bjoc.5.41

• encapsulation of one perchlorate, hydrogen sulfate and hexafluorosilicate, respectively inside the cage of L1 in their protonated states. Further, detailed structural analysis on complex 1 reveals that the hexaprotonated L1 encapsulates a perchlorate via two N–H···O and five O–H···O hydrogen bonds from

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• the reaction products is proposed and supported by DFT calculations. Keywords: consecutive reactions; intramolecular cyclization; molecular modelling; spiro compounds; X-ray structural analysis; Introduction Compounds for optoelectronic applications with electroluminescent (e.g. organic light

Molecular recognition. 1. Crystal structures of hexaazamacrocyclic amines containing p-xylylene spacers and their adducts with acids

• Teresa Borowiak,
• Grzegorz Dutkiewicz,
• Maciej Kubicki,
• Marek Pietraszkiewicz,
• Agnieszka Gil and
• Rainer Mattes

Beilstein J. Org. Chem. 2005, 1, No. 16, doi:10.1186/1860-5397-1-16

• supramolecular structure is similar to that of 2[8] although in the last one water molecules co-crystallize with the chair-like molecules of 2. Description of Supporting Information Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Centre, CCDC 279700