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

• (+), 133.6 (+), 129.0 (+), 50.3 (+), 41.7 (+), 37.0 (−), 33.2 (−), 13.5 (+), 5.2 (−), 4.1 (−) ppm; MS (EI, 70 eV) m/z (%): 340 (15), 171 (21), 170 (21), 169 (100), 155 (27), 142 (11), 141(19), 129 (44), 128 (20), 115 (10). X-ray structure determination Numerical details are presented in Table 1. Data

Stereogenic boron in 2-amino-1,1-diphenylethanol-based boronate–imine and amine complexes

• Sebastian Schlecht,
• Walter Frank and
• Manfred Braun

Beilstein J. Org. Chem. 2011, 7, 615–621, doi:10.3762/bjoc.7.72

• the nitrogen from sp2 to sp3. The structure determination 10·CH3OH reveals a hydrogen bridge of the amine hydrogen atom directed to the oxygen atom of the alcohol. The fact that the NH group functions as the hydrogen-bond donor is attributed to an enhanced acidity that is caused by the coordinate bond

• ]+ 511.15954, found, 511.15935. Crystal structure determination Crystals of compounds 8 and 10·CH3OH suitable for X-ray analysis were selected by means of a polarization microscope and investigated with a STOE imaging plate diffraction system using graphite monochromatic MoKα radiation (λ = 0.71073 Å). To

A surprising new route to 4-nitro-3-phenylisoxazole

• Henning Hopf,
• Aboul-fetouh E. Mourad and
• Peter G. Jones

Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68

• acetate); lit. mp 114.5 °C [17]; 1H NMR: δ = 9.36 (s, 1H, H-5), 7.70–7.67 (m, 2H, Ar-H), 7.59–7.49 (m, 3H, Ar-H); 13C NMR: δ = 160.6 (C-5), 156.5 (C-3), 133.9 (C-4), 131.1, 129.5, 128.6, 124.7 (Ph). X-Ray structure determination of 4: Crystal data: C9H6N2O3, Mr = 190.16, monoclinic, P21/c, T = −173 °C, a

Synthesis of spiroannulated and 3-arylated 1,2,4-trioxanes from mesitylol and methyl 4-hydroxytiglate by photooxygenation and peroxyacetalization

• Axel G. Griesbeck,
• Lars-Oliver Höinck and
• Jörg M. Neudörfl

Beilstein J. Org. Chem. 2010, 6, No. 61, doi:10.3762/bjoc.6.61

• spectroscopic methods and by X-ray structure determination. Experimental Synthesis of the 4-fluorophenyl derivative 10b: A solution of 290 mg (2.0 mmol) of the hydroperoxide 4 (prepared from methyl 4-hydroxytiglate (3) by the method described in [10]) and 220 mg (2.0 mmol) of 4-fluorobenzaldehyde in 40 ml of

Preparation, structures and preliminary host–guest studies of fluorinated syn-bis-quinoxaline molecular tweezers

• Markus Etzkorn,
• Jacob C. Timmerman,
• Matthew D. Brooker,
• Xin Yu and
• Michael Gerken

Beilstein J. Org. Chem. 2010, 6, No. 39, doi:10.3762/bjoc.6.39

• -frequency shift of the bridgehead proton resonances of the anti-adduct (Δδ = 0.20 ppm). The X-ray structure determination of target compound 16c confirmed indirectly the correct assignment of isomers 9b and 9b′ (vide infra). Oxidation of 9b with Khan’s original protocol [21][22][23] and condensation of the

• solutions suitable for X-ray structure determination (Table 1, Figure 1). In each case, the crystals contained residual ethyl acetate from the purification step, indicating strong binding of the ethyl acetate molecule inside the binding cleft of 16c. Compound 16c crystallizes, with an ethyl acetate solvent

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

• unambiguously identified from NMR spectral data and crystal structure determination (Figure 3). The X-ray structure analysis of compound 5 confirms that of the two conceivable isomers with C2 5a and CS symmetry 5b, the latter was formed as the main product. On applying the Diels–Alder reaction to compounds 1

Reversible intramolecular photocycloaddition of a bis(9-anthrylbutadienyl)paracyclophane – an inverse photochromic system. (Photoactive cyclophanes 5)

• Henning Hopf,
• Christian Beck,
• Jean-Pierre Desvergne,
• Henri Bouas-Laurent,
• Peter G. Jones and
• Ludger Ernst

Beilstein J. Org. Chem. 2009, 5, No. 20, doi:10.3762/bjoc.5.20

• ). 9-(anthrylmethyl)triphenylphosphonium bromide was easily obtained from triphenylphosphine and 9-bromomethylanthracene. 2 X-ray structure analysis Single crystals suitable for X-ray structure determination were grown by slow evaporation of a solution of 2 (150 mg) in dichloromethane (10 mL) by

• ppm (CH2). The mass spectrum was found to be identical to that of compound 2. 3. X-Ray structure determination of 2·1/2CH2Cl2 Crystal data: C52.5H41Cl, Mr = 707.30, monoclinic, P21/c, T = −100 °C, a = 17.716(3), b = 10.236(2), c = 21.811(3) Å, β = 110.523(8)°, U = 3704.1 Å3, Z = 4, F(000) = 1492, λ

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48

• , total synthesis is a key tool for the complete structure determination of ACGs, since several absolute configurations of stereogenic centres are rather difficult to determine without comparison of the spectroscopic data, and/or the chromatographic properties of several stereoisomers. This review of

Phaeochromycins F–H, three new polyketide metabolites from Streptomyces sp. DSS-18

• Jian Li,
• Chun-Hua Lu,
• Bao-Bing Zhao,
• Zhong-Hui Zheng and
• Yue-Mao Shen

Beilstein J. Org. Chem. 2008, 4, No. 46, doi:10.3762/bjoc.4.46

• ; structure determination; Introduction Marine microorganisms are widely recognized as rich sources of novel natural products [1][2]. In recent years, numerous novel compounds discovered from marine actinomycetes have been reported [3][4][5]. During the course of our search for biologically active substances

• from marine derived actinomycetes, a strain of the genus Streptomyces was isolated from deep sediment collected from the west Pacific. Herein, we report the isolation and structure determination and biological properties of three new polyketides, namely phaeochromycins F (1), G (2) and H (3), from

Radical cascades using enantioenriched 7-azabenzonorbornenes and their applications in synthesis

• David M. Hodgson and
• Leonard H. Winning

Beilstein J. Org. Chem. 2008, 4, No. 38, doi:10.3762/bjoc.4.38

• Information File 92: Full preparative details of all compounds prepared are reported, together with their spectroscopic data. Acknowledgements We thank the EPSRC for funding and Eli Lilly for a scholarship. We also thank Dr. B. Odell (Oxford) for assistance with structure determination using NMR and the

Phase- vanishing halolactonization of neat substrates

• Nicole Windmon and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2008, 4, No. 29, doi:10.3762/bjoc.4.29

• and structure determination [5][6]. Traditionally, a halolactonization is done in a mixture of aqueous solvent and an organic co-solvent in the presence of a base, such as sodium bicarbonate [7][8]. Reagents commonly used in halolactonization are I2/NaHCO3 [9], Br2 [10], IBr [11]and ICl [12]. We

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• adduct in 63% yield following conventional work-up and chromatography. Although an X-ray structure determination was not carried out, the tlc and spectral characteristics provided strong evidence that adduct 6e had the same C4/5 stereochemistry as 6a, b. For example, the coupling constant between H-5/H-6

A hydrogen- bonded channel structure formed by a complex of uracil and melamine

• Reji Thomas and
• G. U. Kulkarni

Beilstein J. Org. Chem. 2007, 3, No. 17, doi:10.1186/1860-5397-3-17

• (see Table 1 and Supporting Information File 1). The intermolecular interactions were analyzed using PLATON package [10] and are listed in Table 2. The crystal structure determination gave the asymmetric unit as shown in Figure 1a. The molecular complex crystallizes in C2/c space group with single

The oxanorbornene approach to 3-hydroxy, 3,4-dihydroxy and 3,4,5-trihydroxy derivatives of 2-aminocyclohexanecarboxylic acid

• Ishmael B. Masesane,
• Andrei S. Batsanov,
• Judith A. K. Howard,
• Raju Mondal and
• Patrick G. Steel

Beilstein J. Org. Chem. 2006, 2, No. 9, doi:10.1186/1860-5397-2-9

• reduction with Zn/HCl followed by addition of (Boc)2O and a large excess of iPr2NEt. At this stage, confirmation of the correct assignment of the relative stereochemistry for each isomer was realised by an X-ray crystallographic structure determination of the endo carbamate 2b (see Supporting Information