C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• copper-mediated electrophilic bromination as the reaction pathway [52][53]. In addition, the bromination experiment of cyclooctene 33 which yielded trans-1,2-dibromocyclooctane 34 also supported the fact that molecular bromine was generated under the catalytic conditions. On the other hand, the

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines

• Dimitra Kontokosta,
• Daniel S. Mueller,
• Dong-Liang Mo,
• Wiktoria H. Pace,
• Rachel A. Simpson and
• Laura L. Anderson

Beilstein J. Org. Chem. 2015, 11, 2097–2104, doi:10.3762/bjoc.11.226

• 10–14, the addition of 1.2 equiv of cyclooctadiene (COD), cyclooctene (COE), norbornadiene (NBD), 1-octene, and dibenzylideneacetone (dba) all improved the yield of the Chan–Lam reaction, but COD was most efficient. Having identified optimal conditions for the synthesis of N-cyclohexenylnitrone 8aa

Ru complexes of Hoveyda–Grubbs type immobilized on lamellar zeolites: activity in olefin metathesis reactions

• Hynek Balcar,
• Naděžda Žilková,
• Martin Kubů,
• Michal Mazur,
• Zdeněk Bastl and
• Jiří Čejka

Beilstein J. Org. Chem. 2015, 11, 2087–2096, doi:10.3762/bjoc.11.225

• ] and such zeolites offer the possibility of their modifications with organometallic moieties in a similar way as mesoporous molecular sieves. Limbach et al. [20] used MWW material as a support for Ru heterogeneous catalyst for cyclooctene oligomerization, however, its activity was rather low. In this

Hexacoordinate Ru-based olefin metathesis catalysts with pH-responsive N-heterocyclic carbene (NHC) and N-donor ligands for ROMP reactions in non-aqueous, aqueous and emulsion conditions

• Shawna L. Balof,
• K. Owen Nix,
• Matthew S. Olliff,
• Sarah E. Roessler,
• Arpita Saha,
• Kevin B. Müller,
• Ulrich Behrens,
• Edward J. Valente and
• Hans-Jörg Schanz

Beilstein J. Org. Chem. 2015, 11, 1960–1972, doi:10.3762/bjoc.11.212

• outstanding performance in the ROMP of dicyclopentadiene (DCPD) and mixtures of DCPD with cyclooctene (COE) in acidic aqueous microemulsion. With loadings as low as 180 ppm, the catalysts afforded mostly quantitative conversions of these monomers while maintaining the size and shape of the droplets throughout

• norbornene (NBE) at 80 °C in microemulsion (91% conversion) [54]. The same conditions failed to polymerize significant amounts of the far less reactive monomers cyclooctene (COE) or cyclooctadiene (COD) with yields below 10%. Later, Heroguez et al. synthesized the 1st generation Grubbs-type macroinitiator 3

• particular the sterically close N-donor ligand. This can also be seen in the cis C=Ru–N angle which is smaller by almost 2° allowing a closer proximity of these two moieties. Catalytic experiments We investigated the catalyst activity of novel complexes 9, 11 and 12 in the ROMP of cyclooctene (COE, [Ru

Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

• Yulia I. Denisova,
• Maria L. Gringolts,
• Alexander S. Peregudov,
• Liya B. Krentsel,
• Ekaterina A. Litmanovich,
• Arkadiy D. Litmanovich,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2015, 11, 1796–1808, doi:10.3762/bjoc.11.195

• achieve a random copolymer of norbornene and cyclooctene. Its rate is limited by the interaction of polyoctenamer-bound carbenes with polynorbornene units, which is hampered, presumably due to steric reasons. Polynorbornene-bound carbenes are detected in very low concentrations throughout the whole

• cis-cyclooctene because of their substantially different monomer reactivities. Keywords: cross-metathesis; 1st generation Grubbs’ catalyst; interchange reactions; kinetics; multiblock copolymer; Introduction A desired sequence of monomer units in a polymer chain can be achieved not only in the

• at the cross-metathesis stage [14]. In our previous communication [15] we reported the obtaining of a copolymer of norbornene (NB) and cis-cyclooctene (COE) by the cross-metathesis of polynorbornene (poly(1,3-cyclopentylenevinylene), PNB) with polyoctenamer (poly(1-octenylene), PCOE). It is

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

• unsubstituted norbornene (M1) and cis-cyclooctene (M6) but also with M4. However, in turn it allows for the synthesis of high molecular weight polymers. The most striking feature, however, is related to the Ru content of the resulting polymers, which were all obtained as white powders. Unlike in many other Ru

• as the organic solvent. While Ru-2 showed low RCM activity, it turned out to be active in ROMP reactions of strained cyclic olefins like norbornenes, 7-oxanorbornenes, norbornadiene and cis-cyclooctene allowing for the synthesis of the corresponding polymers with unprecedented low metal contamination

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• systems which are found in streptorubin B and metacycloprodigiosin [148][149][150]. In this context, the cyclooctene 164 was reacted with the intermediate formed in situ from chloramine-T and elemental selenium [151] and yielded the allylic amine derivative 165 (75%). An N-alkylation with propargyl

Intermolecular addition reactions of N-alkyl-N-chlorosulfonamides to unsaturated compounds

• Gerold Heuger and
• Richard Göttlich

Beilstein J. Org. Chem. 2015, 11, 1226–1234, doi:10.3762/bjoc.11.136

• , sterically not hindered alkene like 1-decene (Table 3, entry 1) still gave reasonable yields of the addition product. The yield is lower in addition to norbornene and cyclooctene, both of which are more sterically hindered and do not allow any mesomeric stabilization of the intermediate radical (Table 3

Novel stereocontrolled syntheses of tashiromine and epitashiromine

• Loránd Kiss,
• Enikő Forró and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2015, 11, 596–603, doi:10.3762/bjoc.11.66

• stereocontrolled approach has been developed for the syntheses of tashiromine and epitashiromine alkaloids from cyclooctene β-amino acids. The synthetic concept is based on the azetidinone opening of a bicyclic β-lactam, followed by oxidative ring opening through ring C–C double bond and reductive ring-closure

• reactions of the cis- or trans-cyclooctene β-amino acids. Keywords: alkaloids; amino acids; ring closure; ring opening; stereocontrolled synthesis; Introduction Indolizidine alkaloids are an important class of naturally occurring compounds which have received considerable attention as a result of their

• (Z-Cl) afforded protected amino ester (±)-3 in 78% yield. In agreement with our earlier observations [40][41][42] C–C double bond functionalization of the cyclooctene β-amino ester via dihydroxylation with N-methyl morpholine N-oxide (NMO) in the presence of OsO4 afforded the corresponding all-cis

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

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

• , entry 13) and cyclooctene (Table 1, entry 15) have furnished DA adducts in excellent yields and good diastereoselectivity ~4:1 (anti:syn) in 6–15 h. Some dienophiles such as p-nitrostyrene (Table 1, entry 5), 4-vinylpyridine (Table 1, entry 10), chlorinated styrene (Table 1, entry 12) and acrylonitrile

Microflow photochemistry: UVC-induced [2 + 2]-photoadditions to furanone in a microcapillary reactor

• Sylvestre Bachollet,
• Kimitada Terao,
• Shin Aida,
• Yasuhiro Nishiyama,
• Kiyomi Kakiuchi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2013, 9, 2015–2021, doi:10.3762/bjoc.9.237

• . However, higher cycloalkenes (cyclohexene and cis-cyclooctene) gave stereoisomeric mixtures even under these direct irradiation conditions. Microflow photochemical syntheses with UVC light are rare. Jamison and coworkers have recently used custom-made quartz coils [32][33], however, these are difficult to

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

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

• colleagues (Figure 17). These chiral bipyridine N,N’-dioxides were utilized in the enantioselective desymmetrization of cis-stilbene oxide and cyclooctene epoxide with SiCl4. Some showed high catalytic activities but with low to moderate enantioselectivities. Among them, chiral bipyridine N,N’-dioxide OC-87

• , the corresponding chlorohydrin was obtained in nearly racemic form. The greater the ring sizes of the cyclic oxides, the higher the enantioselectivities. It was found that the catalyst OC-98 is unique for the desymmetrization of meso-cyclooctene oxide, which was proved to be a very challenging

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• the reductive dexanthylation of adduct 102 derived from 2-allylcyclohexanone, does not undergo an intramolecular HWE condensation to give a cyclooctene derivative upon treatment with sodium hydride. The formation of the cyclooctene ring is not very favourable and cannot compete with the simple aldol

Cyclodextrin nanosponge-sensitized enantiodifferentiating photoisomerization of cyclooctene and 1,3-cyclooctadiene

• Wenting Liang,
• Cheng Yang,
• Masaki Nishijima,
• Gaku Fukuhara,
• Tadashi Mori,
• Andrea Mele,
• Franca Castiglione,
• Fabrizio Caldera,
• Francesco Trotta and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2012, 8, 1305–1311, doi:10.3762/bjoc.8.149

• )-cyclooctene and (Z,Z)-1,3-cyclooctadiene were performed by using the pyromellitate-linked cyclodextrin network polymer, termed “cyclodextrin nanosponge (CDNS)”, as a supramolecular sensitizing host. The photochirogenic behavior of the nanosponges incorporating β- or γ-cyclodextrin was significantly different

• from that reported for the conventional sensitizer-appended monomeric cyclodextrins, affording chiral (E)-cyclooctene and (E,Z)-cyclooctadiene in enantiomeric excesses critically dependent on the solution pH and solvent composition employed, revealing the active roles of chiral void spaces of CDNS in

• the photochirogenic reaction. Keywords: cyclodextrins; 1,3-cyclooctadiene; cyclooctene; nanosponge; photochirogenesis; photoisomerization; Introduction The precise control of chiral photoreactions, or photochirogenesis, is one of the most challenging topics in current photochemistry [1][2][3]. Weak

Hoveyda–Grubbs type metathesis catalyst immobilized on mesoporous molecular sieves MCM-41 and SBA-15

• Hynek Balcar,
• Tushar Shinde,
• Naděžda Žilková and
• Zdeněk Bastl

Beilstein J. Org. Chem. 2011, 7, 22–28, doi:10.3762/bjoc.7.4

• metathesis polymerization (ROMP) of cyclooctene, ring-closing metathesis (RCM) of diallylsilanes and several types of cross-metathesis reactions. High stability of catalysts, reusability and low Ru leaching were also reported. However, the mode of attachment of the Ru species on the silica surface was

• , respectively. The catalytic activity was tested in the RCM of 1,7-octadiene (Scheme 1, entry 1) and diethyl diallylmalonate (DEDAM) (Scheme 1, entry 2), in the metathesis of methyl oleate (Scheme 1, entry 3) and methyl 10-undecenoate (Scheme 1, entry 4), and in the ROMP of cyclooctene (Scheme 1, entry 5

• reactions with 3/MCM-41 and 3/SBA-15. Selectivity near 100% was achieved in all cases. The ROMP reactions were carried out for cyclooctene with both 3/MCM-41 and 3/SBA-15 (cyclooctene/Ru molar ratio = 500, c0cyclooctene = 0.6 mol/L, T = 30 °C). High molecular weight polymers (Mw = 250 000, Mn = 110 000

ROMP-Derived cyclooctene-based monolithic polymeric materials reinforced with inorganic nanoparticles for applications in tissue engineering

• Franziska Weichelt,
• Solvig Lenz,
• Stefanie Tiede,
• Ingrid Reinhardt,
• Bernhard Frerich and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2010, 6, 1199–1205, doi:10.3762/bjoc.6.137

• /bjoc.6.137 Abstract Porous monolithic inorganic/polymeric hybrid materials have been prepared via ring-opening metathesis copolymerization starting from a highly polar monomer, i.e., cis-5-cyclooctene-trans-1,2-diol and a 7-oxanorborn-2-ene-derived cross-linker in the presence of porogenic solvents and

• osteoinductive and provide mechanical support when needed [15]. As an alternative to poly(NBE)-based monoliths, we investigated the preparation of monolithic structures from a highly polar cyclooctene derivative. So far, ROMP-derived monolithic materials have successfully been applied to separation science as

• well as heterogeneous catalysis [16][17][18]. Generally, cyclooctene-derived monoliths differ from their NBE-based counterparts in that they are less prone to oxidation and display higher elastic moduli. With the aim to synthesize organic-inorganic monolithic hybrid materials for application as

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

Light-induced olefin metathesis

• Yuval Vidavsky and
• N. Gabriel Lemcoff

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

• ruthenium cymene complexes (Figure 8) either by replacing the phosphane ligand in complex 12 by NHC ligands or via direct synthesis from 13. Complexes 15 and 16 were tested as photoactivated ROMP catalysts. In all cases cyclooctene was used as a standard cyclic olefin monomer for the polymerisation studies

• . Illuminating 15 or 16 with intense visible light, or even with regular laboratory lighting, revealed a dramatic improvement in their ROMP activity. Results of PROMP by complex 16g (Mes ligand) and cyclooctene are summarised in Table 2. The large difference in polymer molecular weight between the dark and light

• reactions was not explained, even though it is slightly counterintuitive. In order to improve the understanding of the photoactivation mechanism, complex 16g was irradiated by visible light both in the presence and absence of cyclooctene. NMR and UV spectra confirmed the release of p-cymene from the complex

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

• aliphatic protons correlate well with the data for 1,6-dihydro-1,6-methanobenzo[d]cyclooctene, a compound with a similar carbon framework described by Banciu and co-workers [7]. Compound 13 was characterised by NMR spectroscopy, mass spectrometry and by single crystal X-ray crystallography (see below). The

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• new eight-membered carbasugars (Figure 2, A = OH) and related aminocyclitols (A = NHR) from C2-symmetrical L-ido- or D-manno- cyclooctene, easily available by ring closing metathesis of 1,9-diene derived from L-ido- or D-manno-bis-epoxide [33]. Thus, synthetic potentialities of the newly created

• cyclic double bond were explored to reach hexa-substituted C8-glycomimetics. Results and discussion From the C2-symmetrical L-ido- or D-manno- cyclooctene, 1 or 2, to obtain the C8 hexa-substitued carbasugars a straightfoward approach seemed to be a dihydroxylation, whereas to obtain the corresponding

• aminocyclitols it could be an epoxidation followed by the nucleophilic opening of the epoxide moiety by a primary amine or another nitrogen nucleophile. Accordingly (Scheme 1), treatment of the fully O-protected L-ido-cyclooctene 1 with a 5 mol% aqueous solution of osmium(IV) tetroxide [34] in acetone in the