Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• acids (Ile or Val) are the most stabilizing amino acids in parallel packing arrangements, because they project the hydrocarbon side chain from the β-carbon atom directly into the helical interface, whereas perpendicular packing precludes β-branched residues from occupying these sites and Leu is favored

Gold-catalyzed intermolecular coupling of sulfonylacetylene with allyl ethers: [3,3]- and [1,3]-rearrangements

• Jungho Jun,
• Hyu-Suk Yeom,
• Jun-Hyun An and
• Seunghoon Shin

Beilstein J. Org. Chem. 2013, 9, 1724–1729, doi:10.3762/bjoc.9.198

• = di-t-butyl-o-biphenylphosphine, JohnPhos) formed in situ was used as catalyst, the reaction was more efficient in chlorinated solvents rather than polar aprotic or aromatic hydrocarbon solvents (Table 1, entries 1–7). Contrary to the previous [4 + 2] cycloaddition, formal enyne cross metathesis or [2

Aerobic radical multifunctionalization of alkenes using tert-butyl nitrite and water

• Daisuke Hirose and
• Tsuyoshi Taniguchi

Beilstein J. Org. Chem. 2013, 9, 1713–1717, doi:10.3762/bjoc.9.196

• treatment of the crude product with di-tert-butyl dicarbonate (Boc2O) (Scheme 2). This experiment emphasised the potential of the present multifunctionalization method because the simple unsaturated hydrocarbon 1 can be converted into the highly polar amino-1,4-diol compound in only two steps. The plausible

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• that has all the carbon atoms of the final [5]radialene (3) already in place is 1,2,3,4,5-pentamethylcyclopenta-1,3-diene (8). Formally this hydrocarbon merely has to be dehydrogenated three times to provide the target molecule. To accomplish this goal we first had to replace these hydrogen atoms by a

• to 32 is also summarized in Scheme 7. Since in all our bromination experiments we isolated small amounts of a hydrocarbon that, according to mass spectral analysis, has the formula C20H30, i.e. is a dimer of the starting material, we assume that the permethylcyclopentadienyl radical 33 plays an

• 32) that could lead to [5]radialene (3) in hand, a synthesis of this long missing hydrocarbon is now within sight. Structure of 19 in the crystal; ellipsoids represent 50% probability levels. Structure of 24 in the crystal; ellipsoids represent 30% probability levels. Structure of 26 in the crystal

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• species for the bromination. The generation of CHBr3 was confirmed by NMR spectroscopy and GC–MS spectrometry analysis, indicating that the present bromination involves the homolytic cleavage of a C–Br bond in CBr4 followed by radical abstraction of a hydrogen atom from a hydrocarbon. Keywords

• : bromination; free radical; hydrocarbon; light-emitting diode; photo irradiation; Introduction Bromination reactions of organic compounds are fundamental reactions for providing a wide variety of organic precursors for industrial materials [1][2][3][4][5][6][7][8]. Generally, the bromination of saturated

• the second bromination was not assigned at this point. Conclusion In conclusion, we have developed a method for the hydrocarbon bromination induced by LED irradiation using CBr4 as a bromine source. The present reaction system did not require any additives, catalysts, heating, or inert conditions, and

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

Interplay of ortho- with spiro-cyclisation during iminyl radical closures onto arenes and heteroarenes

• Roy T. McBurney and
• John C. Walton

Beilstein J. Org. Chem. 2013, 9, 1083–1092, doi:10.3762/bjoc.9.120

• saddle points by frequency calculations. The experimental kinetic and spectroscopic data was all obtained in the nonpolar hydrocarbon solvents t-BuPh or cyclopropane. Solvent effects, particularly differences in solvation between the neutral reactants and neutral transition states, were therefore

Intramolecular carbolithiation cascades as a route to a highly strained carbocyclic framework: competition between 5-exo-trig ring closure and proton transfer

• William F. Bailey and
• Justin D. Fair

Beilstein J. Org. Chem. 2013, 9, 537–543, doi:10.3762/bjoc.9.59

• significant that the penultimate olefinic alkyllithium 7 generated in the cascade appears to be resistant to rearrangement by proton transfer in the absence of a catalytic quantity of the hydrocarbon formed upon quenching of 7. In short, 5-exo-trig carbolithiations are robust processes that are much more

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

Caryolene-forming carbocation rearrangements

• Quynh Nhu N. Nguyen and
• Dean J. Tantillo

Beilstein J. Org. Chem. 2013, 9, 323–331, doi:10.3762/bjoc.9.37

• positioned on opposite sides of the hydrocarbon substrate due to the steric congestion at its core (note the position of NH3 throughout Figure 7), a scenario that could be probed by deuterium labeling of farnesyl diphosphate if a suitable caryolene synthase were isolated. The energetics for both pathways

Inter- and intramolecular enantioselective carbolithiation reactions

• Asier Gómez-SanJuan,
• Nuria Sotomayor and
• Esther Lete

Beilstein J. Org. Chem. 2013, 9, 313–322, doi:10.3762/bjoc.9.36

• enantioselectivity, favoring the coordination of the ligand with lithium. While solvent systems composed of hydrocarbon/diethyl ether are effective, the use of THF resulted in almost complete loss of enantioselectivity. The cyclization of amine 37b under identical conditions was less enantioselective than the

Towards a biocompatible artificial lung: Covalent functionalization of poly(4-methylpent-1-ene) (TPX) with cRGD pentapeptide

• Lena Möller,
• Christian Hess,
• Jiří Paleček,
• Yi Su,
• Axel Haverich,
• Andreas Kirschning and
• Gerald Dräger

Beilstein J. Org. Chem. 2013, 9, 270–277, doi:10.3762/bjoc.9.33

• peptides have successfully been used to generate biocompatible materials [10][11]. Conceptually, we planned to first functionalize the hydrocarbon TPX 2 via UV-mediated nitrene insertion to form polymer derivative 4 (Scheme 1) [12][13][14]. Therefore, nitrene precursor 3 was modified with an oligo(ethylene

• plasma treatment with nitrene insertion is a protocol of general importance for the functionalization of biomedical materials based on hydrocarbon-derived polymers. The importance of developing strategies for this kind of copper-free surface functionalization reported here was recently also demonstrated

A chemist and biologist talk to each other about caged neurotransmitters

• Graham C.R. Ellis-Davies

Beilstein J. Org. Chem. 2013, 9, 64–73, doi:10.3762/bjoc.9.8

• "? Chemist: It is well known in the pharmaceutical industry that water solubility is one of the true challenges for drug development. Often drugs are built up around rigid hydrocarbon scaffolds, such substances are inherently hydrophobic. The same issue applies to caged compounds, as in these we add aromatic

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• reactions of the bisallenes would lead to functionalized derivatives that could be useful for other preparative investigations, just as in the pericyclic case [2][3][4][5][6]. The results of these initial studies are presented here. Since the parent hydrocarbon 1 (biallenyl) is rather unstable [7], we

• decided to use the tetramethyl derivative 2 (2,7-dimethylocta-2,3,5,6-tetraene) as a symmetric substrate and the tert-butyl derivative 3 (7,7-dimethylocta-1,2,4,5-tetraene) as an asymmetric starting material for our polar reactions (Scheme 1). Hydrocarbon 2, prepared by Skattebøl in the early 1960s [3][8

• ][9], is a crystalline solid at room temperature and stable for very long times. Bisallene 3, first prepared by Ruitenberg, Kleijn, Westmijze, Meijer and Vermeer [10] is decidedly more stable than the parent hydrocarbon 1: in solution the colorless oil can be kept for weeks at room temperature before

Chemical modification allows phallotoxins and amatoxins to be used as tools in cell biology

• Jan Anderl,
• Hartmut Echner and
• Heinz Faulstich

Beilstein J. Org. Chem. 2012, 8, 2072–2084, doi:10.3762/bjoc.8.233

• hydrocarbon chain instead of the disulfide group. DSP or DSS (248 µmol) were dissolved in 1.0 mL of N,N-dimethylformamide and added to 63 µmol dried aminophalloidin. The reaction was started with 2 µL triethylamine and allowed to proceed under magnetic stirring for 16 h at rt. The reaction was stopped with 10

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• reported by Marvel and co-workers in the 1930s [7][8]; it is the highly substituted and hence stabilized hydrocarbon 3, a hexa-substituted derivative of 2 (Figure 2). Twenty-five years later, Kuhn and Fischer presented the preparation of 1,1,6,6-tetraphenyl-1,2,4,5-hexatetraene (4) as the first conjugated

• bisallene with unsubstituted allene carbon atoms [9]. And finally, also in the 1960s, Jacobs and Prempree reported on the synthesis of the first hexa-alkylated bisallene, hydrocarbon 5 [10][11]. We shall return to the preparation of these three compounds later. The upsurge in interest in allene chemistry is

• the tetramethylbutadiene 22 is first dibromocyclopropanated to the tetrabromide 23, which, on treatment with an organolithium reagent, is debrominated/rearranged to the target hydrocarbon 24. Hydrocarbon 24 is a stable colorless solid that can be worked with under normal laboratory conditions without

Laterally substituted symmetric and nonsymmetric salicylideneimine-based bent-core mesogens

• Sonja Findeisen-Tandel,
• Wolfgang Weissflog,
• Ute Baumeister,
• Gerhard Pelzl,
• H. N. Shreenivasa Murthy and
• Channabasaveshwar V. Yelamaggad

Beilstein J. Org. Chem. 2012, 8, 129–154, doi:10.3762/bjoc.8.15

• , corresponding compounds without hydroxy groups were additionally prepared. In order to focus the study on the effect of lateral substituents, the hydrocarbon chains at both terminal phenyl rings were fixed with dodecyloxy groups. Results and Discussion Monosalicylideneaniline compounds OH 1 bearing the

On the control of secondary carbanion structure utilising ligand effects during directed metallation

• Andrew E. H. Wheatley,
• Jonathan Clayden,
• Ian H. Hillier,
• Alison Campbell Smith,
• Mark A. Vincent,
• Laurence J. Taylor and
• Joanna Haywood

Beilstein J. Org. Chem. 2012, 8, 50–60, doi:10.3762/bjoc.8.5

• solvent or additives to influence the chemoselectivity of lithiation, 6-H was treated at −78 °C with t-BuLi in a hydrocarbon medium to which 1 equiv of PMDTA had been added. The resulting dark purple solution was transferred directly to a freezer (−30 °C) whereupon storage afforded a product that X-ray

• presence of different Lewis bases. In contrast to previous work on carbanion formation in the presence of an aromatic N+O directing group, 6-Lil·L dissolves in hydrocarbon media to reveal two structures in solution. Based on previous work and new DFT studies, we ascribe these as being cis (minor) and trans

Planar-bilayer activities of linear oligoester bolaamphiphiles

• Jonathan K. W. Chui,
• Thomas M. Fyles and
• Horace Luong

Beilstein J. Org. Chem. 2011, 7, 1562–1569, doi:10.3762/bjoc.7.184

• Information File 1, from which it is clear that we could have made similar representations as Figure 1 and Figure 2 with any other pair of compounds. Erratic behaviors may be aesthetically unappealing but should come as no surprise: The hydrocarbon chains that are present in every compound have significant

• -molecule structure–activity relationships for compounds 1–8. Grids are given in the following sequence in each case: Square-top (green); flicker (yellow); multiple-opening (blue); spike (red); erratic (purple). Yellow arrows indicate hydrocarbon homologs; green arrows indicate expansion of aromatic units

One-pot four-component synthesis of pyrimidyl and pyrazolyl substituted azulenes by glyoxylation–decarbonylative alkynylation–cyclocondensation sequences

• Charlotte F. Gers,
• Julia Rosellen,
• Eugen Merkul and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2011, 7, 1173–1181, doi:10.3762/bjoc.7.136

• a long time [16][17]. This prominent appearance results from the electronic transition between the S0 and S1 state [18], as a consequence of low energy frontier molecular orbital transitions [19]. The bicyclic structure of this nonbenzoid hydrocarbon results from a five–seven ring annulation with a

• by our smooth glyoxylation–alkynylation sequences with a variety of unfunctionalized π-nucleophiles, such as pyrazoles, thiophenes, furans, and even the hydrocarbon azulene (1a) [53], we decided to perform optimization studies of the glyoxylation–decarbonylative alkynylation with guaiazulene (1b), a

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• generally mild reaction conditions using straightforward preparative procedures [1][2][3][4][5][6][7][8][9]. Many such processes also incorporate a rearrangement of the hydrocarbon skeleton present in the starting material, which can lead to unexpected and synthetically interesting outcomes [10][11]. One of

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

• prepare the biscyclopropane analog of 11, the bisvinylcyclopropane 19 (or one of its cis-isomers) and subject this presumably strained hydrocarbon to our photocyclization conditions. Of course, this system also has various options to react, among them the photoisomerization to a mono- or all-cis

• (Figure 3), no reaction takes place from this orientation on irradiation in solution. Since we have already demonstrated that a comparable situation prevails for the simplest compound studied in this series, hydrocarbon 7 (Scheme 3), we conclude that reaction from this anti,anti-conformation is the

• ) gave 2.60 g (10 mmol, 100%) of pure hydrocarbon 7. 1H NMR (200 MHz, CDCl3) δ 6.81 (dd, 2H, J1 = 10.9, J2 = 17.4 Hz), 6.60–6.40 (m, 6H), 5.36 (dd, 2H, J1 = 1.5, J2 = 17.4 Hz), 5.08 (dd, 2H, J1 = 1.5 , J2 = 10.9 Hz), 3.60–3.40 (m, 2H), 3.05–2.86 (m, 6H) ppm; 13C NMR (50.3 MHz, CDCl3) δ 139.3, 138.0

Tribenzotriquinacenes bearing three peripheral or bridgehead urea groups stretched into the 3-D space

• Jörg Tellenbröker and
• Dietmar Kuck

Beilstein J. Org. Chem. 2011, 7, 329–337, doi:10.3762/bjoc.7.43

• derivatives; Introduction In the course of our extended research on polyfunctionalized derivatives of tribenzotriquinacene (TBTQ, 1) and some hydrocarbon congeners 2–4, which provide a great variety of convex–concave molecular building blocks [1][2][3][4][5][6][7], we focused our attention on the synthesis

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• reciprocal polyhedra. The vertices in the closo-boranes correspond to faces in its polycyclic hydrocarbon counterpart and vice versa. The different bonding patterns in the two series are described. Several of these hydrocarbons (cubane, pentagonal dodecahedrane and the trigonal and pentagonal prismanes) are

• − 1–8, and CnHn hydrocarbons (n = 6, 8, 10 … 20; 9–16), the point groups and V, E, F values of the complementary CnHn molecules are collected in Table 1. Bonding comparisons The inverse geometric structures of the closo-boranes and their cage hydrocarbon complementary counterparts are the result of

• , or their corresponding anions [BxHx]2−, where x = 5 through 12, suggests that their complementary hydrocarbon cages CnHn, where n represents the even numbers 4 through 20, should also all be viable, as discussed herein. Synthetic routes to highly symmetrical polycyclic hydrocarbons As already noted

Ene–yne cross-metathesis with ruthenium carbene catalysts

• Cédric Fischmeister and
• Christian Bruneau

Beilstein J. Org. Chem. 2011, 7, 156–166, doi:10.3762/bjoc.7.22

• with acyclic internal olefins up to now. This would allow the introduction of a conjugated diene system into an aliphatic hydrocarbon chain. However, the production of terminal olefins upon ethenolysis of unsaturated fatty acid esters followed by cross-metathesis with an alkyne in one pot has recently