Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• of the superoxide ion as a reagent in organic synthesis is still underexplored. A very few and scattered reports appeared in the literature for the conversion of bicyclic norbornene to substituted nortricyclenes (Scheme 1). In 1966 Kempter and co-workers [26] have synthesized nortricyclenes from

• nortricyclenes using palladium and zinc powder from norbornadiene. The bromination of norbornene [30][31][32] is another route to the nortricyclenes. Here, in this study we report an efficient method for the synthesis of aryl- and vinyl-substituted tetrachloromethylenenortricyclenes from the Diels–Alder (DA

Investigations of thiol-modified phenol derivatives for the use in thiol–ene photopolymerizations

• Sebastian Reinelt,
• Monir Tabatabai,
• Urs Karl Fischer,
• Norbert Moszner,
• Andreas Utterodt and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 1733–1740, doi:10.3762/bjoc.10.180

• ], adaptable thiol–ene networks [29], thiol–yne photopolymerizations [30][31][32], and thiol–norbornene materials [33] only to mention a few of them. However, the design of new monomers – both ene and thiol monomers – for thiol–ene polymerization is a sustained necessity in order to improve the mechanical

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• )PAuOTf was employed under microwave irradiation with a catalyst loading as low as 0.05 mol %, the condensation of TsNH2 to norbornene was realized in quantitative yield. In addition, the introduction of carbene ligands [44] allowed performing the intramolecular hydroamination of N-alkenyl ureas

• . 4.1 Alkylation of active methylene compounds Hydroalkylation of styrenes, indene and norbornene with 1,3-diketones was firstly reported in 2004 by using AuCl3 and AgOTf in 1:3 ratio as the catalyst (Scheme 15) [51]. The addition took place with Markovnikov selectivity in good yields, however optimal

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• substrate for desymmetrization with other reported organocatalysts, and the chlorohydrin 94 was obtained in 90% ee in the presence of 10 mol % of OC-98 in dichloromethane at −90 °C. Interestingly, the tricyclic exo-norbornene oxide afforded the syn-exo-chloroalcohol 123 as the major product in 53% yield 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

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• metathesis; triazole; Findings Polymers functionalized with carbohydrate side chains, also referred to as glycopolymers, constitute important synthetic probes for the study of carbohydrate recognition [1][2][3]. Glycopolymers prepared by ring-opening metathesis polymerization (ROMP) of norbornene and

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

• cyclization was not complete, as 23% of the quenched vinyllithium (4) remained (Table 1, entry 1). Warming reaction mixtures at room temperature for 3 h decreased the proportion of 4 (~6%); however, the yield of the norbornene product, 6, increased from 12% after 1 h to ~30% (Table 1, entries 2 and 3). Longer

• ring closure. Quenching of the reaction mixture then affords 5 and 6 in an approximate ratio of 2:1. In this connection, it should be noted that a 2-methylene-substituted bicyclo[2.2.1]heptane, such as product 5, is known to be more stable than the isomeric norbornene, such as 6 [21]. Clearly, the

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• ) alkoxycarbene. The complex could be generated stoichiometrically when norbornene was utilized as a hydrogen acceptor. The reaction was shown to be general for several methyl ethers and tetrahydrofuran, but other ethers were prone to 1,2-dehydrogenation or decarbonylation [88][89] The use of methyl amines as

• excess azide poisoned the catalyst (presumably by irreversible formation of iridium–azide adducts), the controlled addition of azide to an MTBE solution of (PNP)Ir and norbornene, illuminated by a 23 W halogen bulb, led to efficient catalytic oxidation of MTBE. The net C–H functionalization in this case

• multiple C–H activations, since the active catalysts must either be able to eliminate H2 without unproductive back reactions or must transfer H2 into a sacrificial acceptor (such as norbornene in the cycle described). All in all, these findings provide a framework both for the discovery of new reactions

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• palladium-catalyzed, norbornene-mediated C2-alkylation reaction with a broad spectrum of alkyl bromides [21]. Over the past few years, our group and others have explored C–H bond functionalization reactions using cobalt complexes as inexpensive transition-metal catalysts [22], which often feature mild

• 20% yield, although the product could not be separated in a pure form. Unfortunately, the present catalytic system was not very effective for C2-alkylation with simple olefins. The reaction of 1a with norbornene (2d) afforded the alkylation product 3ad in 30% yield (Scheme 3a). The reaction of 1

• -alkenylation of N-pyrimidylindole, (b) ortho-alkylation of aryl imine, and (c) C2-alkylation of N-pyrimidylindole. Addition of N-pyrimidylindoles to vinylsilanes. Addition of N-pyrimidylindole to norbornene (a) and 1-octene (b). Gram-scale reaction and deprotection of N-pyrimidyl group. Screening of ligands.a

High chemoselectivity in the phenol synthesis

• Matthias Rudolph,
• Melissa Q. McCreery,
• Wolfgang Frey and
• A. Stephen K. Hashmi

Beilstein J. Org. Chem. 2011, 7, 794–801, doi:10.3762/bjoc.7.90

• Intermolecular olefinic trapping reagents We started with the simplest experiments, namely the intermolecular trapping of the gold carbenoid intermediates. When 3 was reacted in the presence of an activated olefin, such as norbornene or styrene, phenol 4 was formed exclusively in essentially quantitative yield

Olefin metathesis in nano-sized systems

• Didier Astruc,
• Abdou K. Diallo,
• Sylvain Gatard,
• Liyuan Liang,
• Cátia Ornelas,
• Victor Martinez,
• Denise Méry and
• Jaime Ruiz

Beilstein J. Org. Chem. 2011, 7, 94–103, doi:10.3762/bjoc.7.13

• ][25]. The three first generations of metallodendrimers 2 and the model complex do not catalyze RCM reactions, but they were efficient catalysts for the ROMP of norbornene under ambient conditions, giving dendrimer-cored stars (Scheme 1 and Scheme 2) [24][25]. Analysis of the molecular weights by size

• exclusion chromatography gave data that were close to the theoretical values, which indicated that all the branches were efficiently polymerized. Dendritic-cored stars with an average of about 100 norbornene units on each dendritic branch were synthesized from the three first generations of ruthenium

• , and these were slightly more reactive ROMP catalysts for the polymerization of norbornene than those carrying cyclohexyl substituents [25]. These new dendritic ligands, in particular those of low generation (with up to 8 branches), also proved very efficient in palladium catalysis [26][27][28][29][30

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• emulsion and miniemulsion [69]. Water-soluble ruthenium alkylidene was used for emulsion polymerization of norbornene, whilst an oil-soluble catalyst was employed for the miniemulsion polymerization of norbornene, 1,5-cyclooctadiene, cyclooctene. Similar to the polymerization of ethylene, which is

• described above, an organic solution of the catalyst was first miniemulsified in water and then the monomer was added to the miniemulsion. The monomer conversion was found to be moderate for the two latter monomers, and relatively high (97%) in the case of norbornene with an obtained particle size of 250 nm

• . Another group compared the dispersion, miniemulsion, and suspension polymerization for the ROMP of norbornene or cyclooctadiene [70]. For the miniemulsions, two approaches were followed, i.e., the addition of a catalyst solution to a miniemulsion of the monomer and the addition of monomer to miniemulsion

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

Beilstein J. Org. Chem. 2010, 6, 1106–1119, doi:10.3762/bjoc.6.127

• from norbornene and oxanorbornene derivatives had high molecular weights (Mw > 150 kDa) and also high monomodal polydispersities (Mw/Mn > 2.3). Polymerisation was also found to occur if the monomer was added after irradiation of the complex. In addition, the initial rate of polymerisation was found to

• species. Osmium precatalysts 11a–f did not polymerise norbornene under standard conditions. However, 5 min irradiation of a toluene solution of the complex with a 200 W Hg lamp led to active catalysts. The more active catalysts were those possessing more sterically hindered phosphane ligands. Thus

• , complexes with larger cone angles θ, such as 11b (θ = 160°) and 11c (θ = 170°) showed strong metathetic activity for PROMP of norbornene and dicylopentadiene in toluene solution or even in aqueous dispersions; by contrast, complexes 11a,d,e,f (θ = 130°, 145°, 120°, 150°) showed slow no reaction even after

Halide exchanged Hoveyda-type complexes in olefin metathesis

• Julia Wappel,
• César A. Urbina-Blanco,
• Mudassar Abbas,
• Jörg H. Albering,
• Robert Saf,
• Steven P. Nolan and
• Christian Slugovc

Beilstein J. Org. Chem. 2010, 6, 1091–1098, doi:10.3762/bjoc.6.125

• norbornene derivatives. Another example of selectivity was observed during the cross metathesis of an internal olefin with an electron deficient alkene, where in the case of 3 no side reaction (i.e., homodimerisation of the electron-deficient olefin) occurred. Thus 3 might prove in the future an interesting

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• nitrobenzene [178] or di-tert-butylnitroxide [169] inhibits the reaction. The addition of olefins such as norbornene or styrene [188] has a similar effect and perfluoroalkyl derivatives of these olefins have been identified in the reaction products. The formation of radicals in the reaction of PhSeNa with

Synthesis and crossover reaction of TEMPO containing block copolymer via ROMP

• Olubummo Adekunle,
• Susanne Tanner and
• Wolfgang H. Binder

Beilstein J. Org. Chem. 2010, 6, No. 59, doi:10.3762/bjoc.6.59

• structurally different norbornene monomers (±)-endo,exo-bicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic acid dimethylester (7), and (±)-endo,exo-bicyclo[2.2.1]-hept-5-ene-2,3-dicarboxylic acid bis(1-oxyl-2,2,6,6-tetramethyl-piperidin-4-yl) ester (9) using ruthenium based Grubbs’ type initiators [(PCy3)2Cl2Ru

• synthesis of norbornene monomers 7 and 9 were obtained from Sigma-Aldrich Chemical Co. (Germany) and used as received without further purification unless otherwise indicated. Bicyclopentadiene (100%), fumaric acid (99+%), thionyl chloride (99+%, Fluka), pyridine (99.8%), methanol and 4-hydroxy-2,2,6,6

• the optimal salt for obtaining the highest S/N ratio. Monomer synthesis 5-Norbornene-endo,exo-2,3-dicarboxylic acid dimethylester, monomer A 7 was synthesised according to reference [11], 5-norbornene-endo, exo-2,3-dicarboxylic acid bis(1-oxyl-2,2,6,6-tetramethyl-piperidin-4-yl) ester, monomer T 9

Synthesis and Diels–Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers

• Bilal Nişancı,
• Erdin Dalkılıç,
• Murat Güney and
• Arif Daştan

Beilstein J. Org. Chem. 2009, 5, No. 39, doi:10.3762/bjoc.5.39

• products 11, 12, 18 and 19, there are two possibilities: exo adduct or endo adduct (Figure 1). The coupling constants between the relevant protons in the norbornene unit are very informative to assign the correct configuration of the substituents [9][10]. The high value of J34 and J3′4′ (2.5–3.5 Hz) in the

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

• norbornene [12][13]. The final product distribution in these systems is found to be heavily dependent on the reactant concentrations as well as on the structure of the substrate. In synthetic applications it is therefore important to be able to bias the rearrangement in favour of the desired product, which

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• Huan Liang Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada 10.3762/bjoc.4.31 Abstract The sordarin family of compounds, characterized by a unique tetracyclic diterpene core including a norbornene system, inhibits protein synthesis in

• sordarin [17] in 2004 and 2006, respectively. Both Kato’s and Mander’s syntheses employed intramolecular Diels-Alder cyclizations to construct the norbornene-like framework, while an intramolecular Pd catalyzed Tsuji-Trost reaction was utilized by the Narasaka group to build the diterpene core. Kato’s

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

• in a larger amount (8–10%). Treatment of 5-norbornene-2-carboxylic acid (7) (3:1 mixture of endo and exo isomers) gave the expected bromolactone 8 along with four byproducts (Scheme 4). GC analysis showed the four byproducts as two pairs of closely spaced peaks (retention times of 8.1 and 8.3 min for

• one pair and 12.5 and 12.6 min for the other pair). Furthermore, GC-MS analysis indicated that the byproducts were the corresponding dibromo compounds. They were tentatively assigned structures 9–12. It was expected that one pair of the dibromo compounds (11 and 12) would form as exo-5-norbornene-2

• -carboxylic acid cannot cyclize and, indeed, a pair of dibromo compounds formed in the amount that approximately corresponded to the amount of the starting exo-5-norbornene carboxylic acid. Another pair of dibromo compounds (assumed to have structures 9 and 10) formed in a combined yield of ~10% (according to

Conformational rigidity of silicon- stereogenic silanes in asymmetric catalysis: A comparative study

• Sebastian Rendler and
• Martin Oestreich

Beilstein J. Org. Chem. 2007, 3, No. 9, doi:10.1186/1860-5397-3-9

• -catalyzed kinetic resolution of donor-functionalized alcohols capable of two-point binding. The reagent-controlled hydrosilylation of norbornene derivative 2 with silane 1a proceeds with a perfect chirality transfer (rac-1a → rac-3a, Scheme 1). [8] Mechanistic investigation of the nature of the