39589-98-5Relevant academic research and scientific papers
Steric and electronic factors influencing recognition by a simple, charge neutral norbornene based anion receptor
Lowe, Adam J.,Dyson, Gail A.,Pfeffer, Frederick M.
, p. 1343 - 1346 (2007)
Based on 1H NMR studies, subtle electronic factors rather than pre-organisation dictate the binding stoichiometry of the new, norbornene based, anion hosts 1 and 2 with acetate, however, the binding of dihydrogenphosphate appears to be based so
The synthesis of fluorinated endcaps: Part 1. the effect of C-7 fluorination on the base-catalyzed monohydrolysis of 5-norbornenyl-2,3-diesters
Rajsfus, David E.,Alter-Zilberfarb, Sari,Frimer, Aryeh A.
, p. 49 - 58 (2013)
In an attempt to improve the thermo-oxidative stability of aerospace polyimides, we have explored the preparation of 7-fluorinated nadic endcaps. The latter are 5-norbonenyl acid esters in a 2-endo,3-endo configuration, which is required for imidization. The most obvious precursor is the corresponding diester and, hence, we carried out a preliminary study of the saponification of the symmetric dimethyl esters of various 7-mono- and 7,7-disubstituted nadic acids (5-norbornenyl-2-endo,3-endo-dicarboxylic acids). These included the 7-fluoro (7c) and 7,7-difluoro (7e) derivatives, as well as the 7,7-diprotio (7a), 7-hydroxy (7b) and 7-oxo (7d) analogs for the purpose of comparison. Contrary to previous reports, and depending on the substitution pattern and the basic conditions used, various amounts of hydrolysis and configuration inversion were observed giving various yields of 2-endo,3-endo monoacid monoesters 8, 2-endo,3-exo monoacids monoester 13, 2-endo,3-endo diacids 6, and/or 2-endo,3-exo diacids 15. Interestingly, the inversion in configuration always occurred at C3-i.e., on the carbon α to the remaining ester-and the 2-exo,3-endo acid ester 14 was not observed. Overall, the order of increasing configuration inversion is dependant on the C7- substituent(s) with H2 2 7-substituent(s), which contribute(s) to the stability of the enolate formed at C3. These results require a novel synthetic approach to 7-fluorinated nadic endcaps.
TETRACARBOXYLIC DIANHYDRIDE, CARBONYL COMPOUND, POLYIMIDE PRECURSOR RESIN, AND POLYIMIDE
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Paragraph 0086-0087, (2021/04/30)
A tetracarboxylic dianhydride which is a compound represented by the following general formula (1): [in the formula (1), A represents one selected from the group consisting of optionally substituted divalent aromatic groups in each of which the number of carbon atoms forming an aromatic ring is 6 to 30, and Ras each independently represent a hydrogen atom or the like], wherein 60% by mass or more of a stereoisomer contained in the compound is an exo/exo type stereoisomer represented by a specific general formula.
Oxathiaborolium-Catalyzed Enantioselective [4 + 2] Cycloaddition and Its Application in Lewis Acid Coordinated and Chiral Lewis Acid Catalyzed [4 + 2] Cycloaddition
Boobalan, Ramalingam,Chein, Rong-Jie
supporting information, p. 6760 - 6764 (2021/09/11)
The nascency of second-generation sulfur-stabilized borenium cations by halophilic Lewis acid SnCl4 leads to highly active chiral Lewis acids that are very effective catalysts for [4 + 2] cycloaddition. Oxathiaborolium pentachlorostannate (5-10 mol %) successfully catalyzed cycloaddition of various dienes and dienophiles to afford cycloadducts with excellent enantioselectivity (20 examples, up to 99% ee). This super Lewis acid also exhibited good enantioselectivity for the first Lewis acid coordinated and chiral Lewis acid catalyzed [4 + 2] cycloaddition to α,β-unsaturated mixed ester amide.
Norbornane-based cationic antimicrobial peptidomimetics targeting the bacterial membrane
Hickey, Shane M.,Ashton, Trent D.,Boer, Gareth,Bader, Christie A.,Thomas, Michael,Elliott, Alysha G.,Schmuck, Carsten,Yu, Heidi Y.,Li, Jian,Nation, Roger L.,Cooper, Matthew A.,Plush, Sally E.,Brooks, Douglas A.,Pfeffer, Frederick M.
supporting information, p. 9 - 22 (2018/10/20)
The design, synthesis and evaluation of a small series of potent amphiphilic norbornane antibacterial agents has been performed (compound 10 MIC = 0.25 μg/mL against MRSA). Molecular modelling indicates rapid aggregation of this class of antibacterial agent prior to membrane association and insertion. Two fluorescent analogues (compound 29 with 4-amino-naphthalimide and 34 with 4-nitrobenz-2-oxa-1,3-diazole fluorophores) with good activity (MIC = 0.5 μg/mL against MRSA) were also constructed and confocal microscopy studies indicate that the primary site of interaction for this family of compounds is the bacterial membrane.
Epimerization of Tertiary Carbon Centers via Reversible Radical Cleavage of Unactivated C(sp3)-H Bonds
Wang, Yaxin,Hu, Xiafei,Morales-Rivera, Cristian A.,Li, Guo-Xing,Huang, Xin,He, Gang,Liu, Peng,Chen, Gong
supporting information, p. 9678 - 9684 (2018/07/21)
Reversible cleavage of C(sp3)-H bonds can enable racemization or epimerization, offering a valuable tool to edit the stereochemistry of organic compounds. While epimerization reactions operating via cleavage of acidic C(sp3)-H bonds, such as the Cα-H of carbonyl compounds, have been widely used in organic synthesis and enzyme-catalyzed biosynthesis, epimerization of tertiary carbons bearing a nonacidic C(sp3)-H bond is much more challenging with few practical methods available. Herein, we report the first synthetically useful protocol for the epimerization of tertiary carbons via reversible radical cleavage of unactivated C(sp3)-H bonds with hypervalent iodine reagent benziodoxole azide and H2O under mild conditions. These reactions exhibit excellent reactivity and selectivity for unactivated 3° C-H bonds of various cycloalkanes and offer a powerful strategy for editing the stereochemical configurations of carbon scaffolds intractable to conventional methods. Mechanistic study suggests that the unique ability of N3? to serve as a catalytic H atom shuttle is critical to reversibly break and reform 3° C-H bonds with high efficiency and selectivity.
Design, Synthesis, and Self-Assembly of Polymers with Tailored Graft Distributions
Chang, Alice B.,Lin, Tzu-Pin,Thompson, Niklas B.,Luo, Shao-Xiong,Liberman-Martin, Allegra L.,Chen, Hsiang-Yun,Lee, Byeongdu,Grubbs, Robert H.
supporting information, p. 17683 - 17693 (2017/12/15)
Grafting density and graft distribution impact the chain dimensions and physical properties of polymers. However, achieving precise control over these structural parameters presents long-standing synthetic challenges. In this report, we introduce a versatile strategy to synthesize polymers with tailored architectures via grafting-through ring-opening metathesis polymerization (ROMP). One-pot copolymerization of an ω-norbornenyl macromonomer and a discrete norbornenyl comonomer (diluent) provides opportunities to control the backbone sequence and therefore the side chain distribution. Toward sequence control, the homopolymerization kinetics of 23 diluents were studied, representing diverse variations in the stereochemistry, anchor groups, and substituents. These modifications tuned the homopolymerization rate constants over 2 orders of magnitude (0.36 M-1 s-1 homo -1 s-1). Rate trends were identified and elucidated by complementary mechanistic and density functional theory (DFT) studies. Building on this foundation, complex architectures were achieved through copolymerizations of selected diluents with a poly(d,l-lactide) (PLA), polydimethylsiloxane (PDMS), or polystyrene (PS) macromonomer. The cross-propagation rate constants were obtained by nonlinear least-squares fitting of the instantaneous comonomer concentrations according to the Mayo-Lewis terminal model. In-depth kinetic analyses indicate a wide range of accessible macromonomer/diluent reactivity ratios (0.08 1/r2 20), corresponding to blocky, gradient, or random backbone sequences. We further demonstrated the versatility of this copolymerization approach by synthesizing AB graft diblock polymers with tapered, uniform, and inverse-tapered molecular "shapes." Small-angle X-ray scattering analysis of the self-assembled structures illustrates effects of the graft distribution on the domain spacing and backbone conformation. Collectively, the insights provided herein into the ROMP mechanism, monomer design, and homo- and copolymerization rate trends offer a general strategy for the design and synthesis of graft polymers with arbitrary architectures. Controlled copolymerization therefore expands the parameter space for molecular and materials design.
Palladium(0)-Catalyzed Methylcyclopropanation of Norbornenes with Vinyl Bromides and Mechanism Study
Mao, Jiangang,Xie, Hujun,Bao, Weiliang
supporting information, p. 3678 - 3681 (2015/08/18)
An unusual methylcyclopropanation from [2 + 1] cycloadditions of vinyl bromides to norbornenes catalyzed by Pd(OAc)2/PPh3 in the presence of CH3ONa and CH3OH has been established. A methylcyclopropane subunit was installed by a 3-fold domino procedure involving a key protonation course. Preliminary deuterium-labeling studies revealed that the proton came from methyl of CH3OH and also exposed an additional hydrogen/deuterium exchange process. These two proton-concerned reactions were fully chemoselective.
Synthesis and evaluation of cationic norbornanes as peptidomimetic antibacterial agents
Hickey, Shane M.,Ashton, Trent D.,Khosa, Simren K.,Robson, Ryan N.,White, Jonathan M.,Li, Jian,Nation, Roger L.,Yu, Heidi Y.,Elliott, Alysha G.,Butler, Mark S.,Huang, Johnny X.,Cooper, Matthew A.,Pfeffer, Frederick M.
supporting information, p. 6225 - 6241 (2015/06/08)
A series of structurally amphiphilic biscationic norbornanes have been synthesised as rigidified, low molecular weight peptidomimetics of cationic antimicrobial peptides. A variety of charged hydrophilic functionalities were attached to the norbornane scaffold including aminium, guanidinium, imidazolium and pyridinium moieties. Additionally, a range of hydrophobic groups of differing sizes were incorporated through an acetal linkage. The compounds were evaluated for antibacterial activity against both Gram-negative and Gram-positive bacteria. Activity was observed across the series; the most potent of which exhibited an MIC's ≤ 1 μg mL-1 against Streptococcus pneumoniae, Enterococcus faecalis and several strains of Staphylococcus aureus, including multi-resistant methicillin resistant (mMRSA), glycopeptide-intermediate (GISA) and vancomycin-intermediate (VISA) S. aureus.
Polyethylene as a Cosolvent and Catalyst Support in Ring-Opening Metathesis Polymerization
Suriboot, Jakkrit,Hobbs, Christopher E.,Guzman, William,Bazzi, Hassan S.,Bergbreiter, David E.
, p. 5511 - 5516 (2015/09/02)
Polyethylene oligomers (PEOlig) can be used as cosolvents and sometimes soluble catalyst supports in ring-opening metathesis polymerization (ROMP) reactions. As a catalyst support, this polyolefin serves as an N-heterocyclic carbene ligand for a ROMP catalyst, making it soluble at 70 °C and insoluble at room temperature. As a cosolvent, unfunctionalized PE oligomers facilitate quantitative separation of PEOlig-bound Ru-catalyst residues from polymer products. In these cases, the insolubility of the unfunctionalized polyethylene (Polywax) and its entrapment of the PEOlig-supported Ru residue in the product phase at room temperature afford ROMP products with Ru contamination lower than other procedures that use soluble catalysts. These separations require only physical processes to separate the product and catalyst residues - no additional solvents are necessary. Control experiments suggest that most (ca. 90%) of the Ru leaching that is seen results from Ru byproducts formed in the vinyl ether quenching step and not from the polymerization processes involving the PEOlig-supported Ru complex. (Chemical Equation Presented).
