Ring-opening polymerization of 1 -ethylbicyclo[2.2.1] hept-2-ene

1-Ethylbicyclo[2.2.1]hept-2-ene has been polymerized using a range of metathesis catalysts and the structure of the polymers determined by ¹³C n.m.r. spectroscopy. For a given catalyst the cis double bond content was lower and the head-tail bias greater than for polymers of the 1-methyl analogue. This is interpreted in terms of enhanced steric and polar effects brought about by the ethyl substituent.     

Metathesis ring opening polymerization of 5,6-dimethylenebicyclo[2.2.1]hept-2-ene

5,6-Dimethylenebicyclo[2.2.1]hept-2-ene ( I ) polymerizes in the presence of the two-component ring opening metathesis polymerization (ROMP) initiators WCl₆/(CH₃)4Sn and MoCl₅/(CH₃)4Sn. The product polymers were insoluble in all of many solvents investigated and are presumably cross-linked. The product polymers were investigated by IR and solid state ¹³C NMR spectroscopy, which established that the material consisted predominantly of poly(1,4-(2,3-dimethylene-cyclopentylene)vinylene) ( II ). A possible alternative route to II via thermal dehydrochlorination of poly(1,4-(2,3-bis(chloromethyl)cyclopentylene) vinylene) ( IV ) was also examined.     

Amphiphilic macromolecular nanostructure materials derived from 5-(octanoate methyl)bicyclo[2.2.1]hept-2-ene and 5-(phthalimide methyl)bicyclo[2.2.1]hept-2-ene via ring-opening metathesis copolymerization

Novel highly stable polynorbornenes with self-assembling amphiphilic architecture containing hydrophilic ammonium salt and hydrophobic alkyl ester group were obtained via ring-opening metathesis polymerization (ROMP) of 5-(octanoate methyl)bicyclo[2.2.1]hept-2-ene (NBMO) and 5-(phthalimide methyl)bicyclo[2.2.1]hept-2-ene (NBMPI), hydrogenation, hydrazinolysis, and subsequent quaternization. Polymeric micelles of such amphiphilic random and block polynorbornenes formed in solvents by varying the content of ammonium salts were investigated. Amphiphilic block copolymers exhibited perfect spherical morphology. Nanoscale polymeric micelles of random copolymers with 50-75 mol% of ammonium salts were roughly spherical in shape, while the morphologies of micelles transferred into network-like aggregates as hydrophilic contents of the random copolymers are higher than 80 mol%. The formation and fine structures of micelles were investigated by dynamic light scattering (DLS), TEM, and fluorescence technique using pyrene as fluorescence probe.     

13C N.m.r. Spectra of ring-opened polymers of 1-methylbicyclo[2.2.1]hept-2-ene and their hydrogenated products

The ¹³C n.m.r. spectra of the title polymers have been completely assigned for a comprehensive range of cis contents (σ_c = 0–1) and head-tail bias (HT/(HH + TT) = 1 −∞). In the unsaturated polymers (II), cis HH dyads are never found, so that all-cis polymers are also all-Ht, but cis TT dyads are formed in cis-trans polymers, equal to the difference between trans HH and trans TT. The olefinic region consists of seven triplets; two each from cis HT and trans HT, and one each from cis TT, trans TT and trans HH. In the case of trans each triplet consists of a main centre peak due to ttt and ctc sequences and two wing peaks due to ttc and ctt sequences, as defined in the text. The upfield peaks also show cc/ct or tt/tc splittings as well as HH/HT or TT/TH splittings in most cases. In the saturated polymers C⁶ is sensitive to m/r ring dyad sequences. A corrected assignment is given for the hydrogenated polymer of norbornene.     

13C n.m.r. spectra of polymers made by ring-opening polymerization of (±)- and (+)-exo-5-methylbicyclo [2.2.1] hept-2-ene using metathesis catalysts

A range of olefin metathesis catalysts has been used to prepare ring-opened polymers of (±)- and (+)-exo-5-methylbicyclo [2.2.1] hept-2-ene, (l), having cis double bond contents of 11–100%. The ¹³C n.m.r. spectra of these polymers are interpreted in terms of TH, TT, HH, HT and tt, tc, ct, cc structures (T = tail, H = head, referring to methyl groups; t = trans, c = cis, referring to double bonds). The all-cis polymer has a fully-syndiotactic ring sequence, but polymers with less than 55% cis double bonds have an atactic ring sequence. The substitution shift parameters indicate that the cyclopentane rings in the polymer chain adopt the puckered conformation which minimizes non-bonded repulsion between the cis-1,3-olefinic substituents.     

UNIFAC模型预测乙烯基环己烯-乙烯基降冰片烯气液相平衡数据

以乙烯基环己烯一乙烯基降冰片烯为体系,在低压下,将气相视为理想气体,液相为非理想溶液的情况下,用UNIFAC模型估算了液相活度系数,得到了在8．0kPa下此二元体系的气液平衡数据,并与文献值比较,拟合结果较好。结果表明在缺乏此体系的气液平衡数据时,可以用UNIFAC模型估算作为基础数据,以便顺利进行工程设计。     

1H n.m.r. spectra of ring-opened polymers of 1-methylbicyclo[2.2.1]hept-2-ene

¹H n.m.r. spectra of the title polymers containing 0%, 57% and 100% cis double bonds and having various degrees of head-tail (HT) bias have been analysed. The olefinic protons give distinct signals for HH, HT and TT trans dyads, also for HT and TT cis dyads, but HH cis dyads are not present in any polymer. The ring protons adjacent to the double bonds also give distinct cis and trans signals as do the methyl protons. The latter give four lines, assigned to cc, ct, tc and tt double bond pairs, and their intensities indicate a somewhat blocky cis/trans distribution for polymers having a high cis content. There is no fine structure which can be positively assigned to ring tacticity effects.     

N-(叔丁氧羰基)-2-氮杂双环[2.2.1]庚-5-烯-3-酮的手性拆分

(-)-(1R,4S)-N-(叔丁氧羰基)-2-氮杂双环[2.2.1]庚-5-烯-3-酮是抗艾滋病药物阿巴卡韦的重要中间体。今以2-氮杂双环[2.2.1]庚-5-烯-3-酮为原料,先与(Boc)2O反应生成外消旋体(±)-N-(叔丁氧羰基)-2-氮杂双环[2.2.1]庚-5-烯-3-酮,再以固定化脂肪酶作为拆分试剂选择性拆分制得。试验中分别使用了三种酶,三种酶均表现出较好的反应活性和较高的反应收率,其中固定化酶Lipozyme RM IM的反应活性最高,对其催化的酶促反应进行了优化,得到最佳的反应条件:以异丙醚为反应溶剂,酶与底物质量投料比为1.5/2.0,反应温度为30℃,收率46.5%,对映体过量大于99%。结构经1H-NMR确证。该方法成本低,酶的选择性、催化活性和反应收率高。     

Aqueous ring-opening metathesis polymerization of exo-7-oxabicyclo [2.2.1] hept-5-ene-2,3-dicarboximide

The aqueous ring-opening metathesis polymerization of the exo-Diels-Alder adduct of furan and maleimide was accomplished using an “activated Ruthenium” catalyst present in the supernatant of a RuCl₃-catalyzed aqueous polymerization of furan-dimethylacetylene dicarboxylate adduct. The polymer was characterized by solution ¹H? and ¹³C-NMR, IR, DSC, and viscometry. Characterization revealed an intact imide group and the possibility of high-temperature applications. © 1993 John Wiley & Sons, Inc.     

Differential biohydrogenation and isomerization of [U-13C]Oleic and [1-13C]Oleic acids by mixed ruminal microbes

The additional mass associated with ¹³C in metabolic tracers may interfere with their metabolism. The comparative isomerization and biohydrogenation of oleic, [1-¹³C]oleic, and [U-¹³C]oleic acids by mixed ruminal microbes was used to evaluate this effect. The percent of stearic, cis-14 and- 15, and trans-9 to-16 18∶1 originating from oleic acid was decreased for [U-¹³C]oleic acid compared with [1-¹³C]oleic acid. Conversely, microbial utilization of [U-¹³C]oleic acid resulted in more of the ¹³C label in cis-9 18∶1 compared with [1-¹³C]oleic acid (53.7 vs. 40.1%). The isomerization and biohydrogenation of oleic acid by ruminal microbes is affected by the mass of the labeled tracer.     

NMR spectroscopic characterisation of the microstructure of poly(dimethyl 7-oxabicyclo[2.2.1]hept-2-ene-exo,exo-5,6-dicarboxylate)

Summary Samples of title polymer have been prepared by ring-opening metathesis polymerisation of dimethyl 7-oxabicyclo[2.2.1]hept-2-ene-exo, exo-5,6-dicarboxylate I using a ruthenium catalyst. Comparison of the NMR spectra obtained from samples prepared in two different solvents enables the differences in polymer microstructure to be established. When tetrahydrofuran is used as solvent, a highly tactic polymer with high trans vinylene content is produced. In contrast, when ethanol/water is used as solvent, the polymer exhibits an atactic microstructure and contains approximately equal amounts of cis and trans vinylene bonds.     

Detection ofcis-vaccenic acid in palm oil by13C NMR spectroscopy

The NMR signals of the carbonyl and olefinic carbons of the oils of some species of palm show some relatively weak peaks at characteristic positions that have not been identified previously. These peaks are most intense in the oil of the speciesElaeis oleifera. On the basis of the chemical shift data of the carbonyl and olefinic carbons of several synthetic monoenic triacylglycerols and of the packed-column gas chromatogram of the methyl esters of the oil ofE. oleifera, the peaks in question are assigned tocis-vaccenic acid (18∶1,[cis]-11).¹³C NMR spectroscopy is an effective technique for the detection ofcis-vaccenic acid and other monounsaturated fatty acids in vegetable oils or fats.     

13C NMR spectroscopy of cationic copolymers of acrylamide

Summary Random copolymers of acrylamide and a quaternary ammonium acrylate monomer have been investigated by¹³C NMR spectroscopy in aqueous solution. Cleavage of the ester function has been shown to occur in mild alkaline media with a simultaneous intrachain reaction giving imide group formation. Sequential length distribution of the comonomers has been analyzed from triads composition and the experimental results lead to a nearly Bernouillian statistics although a more alternating distribution would be predicted from the reactivity ratios. This fact has been attribtued to the compositional heterogeneity of our copolymers which have been prepared at high degree of conversion.     

Authentication of marine oils using 13C NMR spectroscopy

NMR spectroscopy has been particularly valuable in the study of lipids, since it provides qualititative and quantitative information on chemically diverse compounds in a non‐destructive and non‐selective fashion. NMR gives a fingerprint of the sample analyzed and may be used as a rapid profiling technique. Combined with chemometrics and databases with relevant authentic samples, ¹³C NMR is a powerful tool for authentication of marine oils.     

Analytical13C NMR spectroscopy of fatty quaternary amines

Natural abundance¹³C nuclear magnetic resonance spectroscopy (CMR) has been used for the rapid, nondestructive analysis of fatty quaternary ammonium compounds. Quantitative analysis of mixtures of mono-, di-and tri-fatty ammonium chlorides can be accommpublished under conditions that do not involve heat or extremes of pH and that are independent of solvent present. In order to determine optimal conditions for quantitative studies, carbon spin lattice relaxation times (T₁) and nuclear Overhauser effects (NOE) were determined for each of the components. The method of internal standard addition was used to determine reproducibility and accuracy of the method for the measurement of mono-and tri-fatty quaternary components in material consisting predominantly (i.e., greater than 90%) of di-fatty-dimethyl ammonium chloride.     

Synthesis and lithographic characterization of poly[(dihydrocarveol)-co-(1,1-dimethylethyl bicyclo[2.2.1]hept-5-ene-2-carboxylate)-co-(maleic anhydride)]

A new ArF single-layer resist polymer, poly(dihydrocarveol-co-1,1-dimethylethyl bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-maleic anhydride) has been synthesized by radical polymerization. The molar composition of synthesized resist polymer was confirmed by elemental analysis. The obtained molar composition was 0.25:0.35:0.40. This resist polymer was found to be stable up to 230 °C, but above 250 °C it underwent rapid thermal deprotection of the tert-butyl groups by releasing carbon dioxide and 2-methylpropene. The deprotection temperature was established by DSC and TGA. Using the resist, 0.14 µm L/S pattern was obtained at 26 mJ/cm⁻² doses, using an ArF stepper and the developer of 2.38 wt% tetramethyl ammonium hydroxide aqueous solution. © 1999 Society of Chemical Industry     

Development of selective estrogen receptor modulator (SERM)-like activity through an indirect mechanism of estrogen receptor antagonism: defining the binding mode of 7-oxabicyclo[2.2.1]hept-5-ene scaffold core ligands

Previously, we discovered estrogen receptor (ER) ligands with a novel three-dimensional oxabicyclo[2.2.1]heptene core scaffold and good ER binding affinity act as partial agonists via small alkyl ester substitutions on the bicyclic core that indirectly modulate the critical switch helix in the ER ligand binding domain, helix 12, by interactions with helix 11. This contrasts with the mechanism of action of tamoxifen, which directly pushes helix 12 out of the conformation required for gene activation. We now report that a much larger substitution can be tolerated at this position of the bicyclic core scaffold, namely a phenyl sulfonate group, which defines a novel binding epitope for the estrogen receptor. We prepared an array of 14 oxabicycloheptene sulfonates, varying the phenyl sulfonate group. As with the parent compound, 5,6-bis-(4-hydroxyphenyl)-7-oxabicyclo[2.2.1]hept-5-ene-2-sulfonic acid phenyl ester (OBHS), these compounds showed preferential affinity for ERα, and the disposition and size of the phenyl substituents were important determinants of the binding affinity and selectivity of these compounds, with those having ortho substituents giving the highest, and para substituents the lowest affinities for ERα. A few analogues exhibit ERα binding affinities that are comparable to or, in the case of the ortho-chloro analogue, higher than that of OBHS itself. In cell-based studies, we found several compounds with activity profiles comparable to tamoxifen, but acting entirely as indirect antagonists, allosterically interfering with recruitment of coactivator proteins to the receptor. Thus, the OBHS binding epitope represents a novel approach to the development of estrogen receptor antagonists via an indirect mechanism of antagonism.