- Bifunctional polymeric organocatalysts and their application in the cooperative catalysis of Morita-Baylis-Hillman reactions
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A series of soluble, noncross-linked polystyrene-supported tri-phenylphosphane and 4-dimethylaminopyridine reagents were prepared. Some of these polymeric reagents contained either alkyl alcohol or phenol groups on the polymer backbone. The use of these materials as organocatalysts in a range of Morita-Baylis-Hillman reactions indicated that hydroxyl groups could participate in the reactions and accelerate product formation. In the cases examined, phenol groups were more effective than alkyl alcohol groups for catalyzing the reactions. This article is one of the first reports of the synthesis and use of non-natural, bifunctional polymeric reagents for use in organic synthesis in which both functional groups can cooperatively participate in the catalysis of reactions.
- Kwong, Cathy Kar-Wing,Huang, Rui,Zhang, Minjuan,Shi, Min,Toy, Patrick H.
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- Mechanistic Study of Palladium-Catalyzed Hydroesterificative Copolymerization of Vinyl Benzyl Alcohol and CO
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The copolymerization of vinyl benzyl alcohol (VBA) and carbon monoxide (CO) to give a new polyester poly(VBA-CO) has been achieved via palladium-catalyzed hydroesterification. Reaction conditions involve moderate temperatures, moderate to low CO pressures, and low catalyst loadings to give a low molar mass (Mn 3-4 kg/mol) polymer as a 2:1 mixture of linear to branched repeat units. The polymer molar mass increase is consistent with a step-growth polymerization mechanism, and ester yields of >97% are achieved within 24 h. However, increases in Mn cease beyond 16 h. Control experiments indicate that the degree of polymerization is limited due to a combination of side reactions such as alcoholic end-group oxidation, hydroxycarbonylation, and alcohol acetylation, which lead to the degradation of monomeric and polymeric end groups. When a less promiscuous substrate is used such as 10-undecenol, higher molar masses (Mn 16 kg/mol) are achieved. This method has the potential to be a mild route to new polyester architectures with appropriate mitigation of side reactions.
- Yee, Gereon M.,Wang, Tong,Hillmyer, Marc A.,Tonks, Ian A.
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- Synthesis and application of polytetrahydrofuran-grafted polystyrene (PS-PTHF) resin supports for organic synthesis
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Cross-linked polystyrene (PS) with polytetrahydrofuran (PTHF) chains were prepared for use in solid phase organic synthesis (SPOS). The resins were prepared from styrene, styrene-PTHF macromonomers and cross-linkers 1,4-bis[4-vinylphenoxy]butane or divinylbenzene by suspension polymerization. The styrene-PTHF macromonomers were prepared by cationic polymerization of 4-vinylbenzyl bromide and 4-(4-vinylphenoxy)butyl iodide activated by silver hexafluoroantimonate and 4-(5-hydroxypentyl)styrene activated by triflic anhydride. Alternatively, polytetrahydrofuran-grafted polystyrene (PS-PTHF) resins could also be directly prepared from 5-hydroxypentyl JandaJel by cationic polymerization using triflic anhydride as the initiator. These PS-PTHF resins exhibited good swelling characteristics across a wide spectrum of polar and non-polar solvents. These resins were used in the synthesis of 3-methyl-1-phenyl-2-pyrazolin-5-one, which requires β-ketoester formation at low temperature (-78°C), resulting in good yield and product purity; whereas the same synthesis carried out on PEG-grafted PS (PS-PEG) resin resulted in incomplete synthesis.
- Shimomura, Osamu,Se Lee, Byoung,Meth, Sergio,Suzuki, Hiroki,Mahajan, Suresh,Nomura, Ryoki,Janda, Kim D.
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- Aromatic Nitrogen Mustard-Based Autofluorescent Amphiphilic Brush Copolymer as pH-Responsive Drug Delivery Vehicle
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Delivery of clinically approved nonfluorescent drugs is facing challenges because it is difficult to monitor the intracellular drug delivery without incorporating any integrated fluorescence moiety into the drug carrier. The present investigation reports the synthesis of a pH-responsive autofluorescent polymeric nanoscaffold for the administration of nonfluorescent aromatic nitrogen mustard chlorambucil (CBL) drug into the cancer cells. Copolymerization of poly(ethylene glycol) (PEG) appended styrene and CBL conjugated N-substituted maleimide monomers enables the formation of well-defined luminescent alternating copolymer. These amphiphilic brush copolymers self-organized in aqueous medium into 25-68 nm nanoparticles, where the CBL drug is enclosed into the core of the self-assembled nanoparticles. In vitro studies revealed ~70% drug was retained under physiological conditions at pH 7.4 and 37 °C. At endolysosomal pH 5.0, 90% of the CBL was released by the pH-induced cleavage of the aliphatic ester linkages connecting CBL to the maleimide unit. Although the nascent nanoparticle (without drug conjugation) is nontoxic, the drug conjugated nanoparticle showed higher toxicity and superior cell killing capability in cervical cancer (HeLa) cells rather than in normal cells. Interestingly, the copolymer without any conventional chromophore exhibited photoluminescence under UV light irradiation due to the presence of "through-space" π- π interaction between the C=O group of maleimide unit and the adjacent benzene ring of the styrenic monomer. This property helped us intracellular tracking of CBL conjugated autofluorescent nanocarriers through fluorescence microscope imaging. Finally, the 4-(4-nitrobenzyl)pyridine (NBP) colorimetric assay was executed to examine the ability of CBL-based polymeric nanomaterials toward alkylation of DNA.
- Saha, Biswajit,Choudhury, Neha,Seal, Soma,Ruidas, Bhuban,De, Priyadarsi
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- High refractive index transparent nanocomposites prepared by in situ polymerization
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High refractive index transparent nanocomposites have been developed by in situ polymerization of a precursor that contains functional monomers and surface modified anatase TiO2 nanoparticles for optoelectronic applications. The monomers are in the liquid form, so environmentally friendly solventless precursors can be prepared. The precursor can be processed into various shapes or thick films (>50 microns) of the nanocomposite. The relationships of the chemical structure of the organic matrix, nanoparticle content and dispersity with the refractive index, transparency, mechanical and thermal properties are systematically investigated. The refractive index, and mechanical and thermal properties of the nanocomposite are increased with increasing TiO2 content and aromatic structure in the organic matrix due to their rigid characteristics. The transparency of the nanocomposite is increased with increasing TiO2 content and dispersity. At the same loading of nanoparticles, the higher dispersity and the better transparency are due to the less extent of Rayleigh scattering. At 18 vol% (60 wt%) of TiO2, the acetic acid modified TiO2/poly(4-vinyl benzyl alcohol) nanocomposite has a refractive index of 1.73 and excellent transparency (>85% from 500 nm to 800 nm). The refractive index of the nanocomposite can be further increased to 1.77 by replacing aliphatic acetic acid modified TiO2 with aromatic phenyl acetic acid modified TiO2. The results of this work provide new knowledge and a new pathway to design a polymer based high refractive index material.
- Tsai, Chieh-Ming,Hsu, Sheng-Hao,Ho, Chun-Chih,Tu, Yu-Chieh,Tsai, Hsin-Chien,Wang, Chung-An,Su, Wei-Fang
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- The formation of core cross-linked star polymers containing cores cross-linked by dynamic covalent imine bonds
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Diblock copolymers possessing amino or aldehyde functions within one of their blocks were prepared using RAFT polymerization techniques. These polymers were shown to cross-link through dynamic imine bonds to form core cross-linked star polymers which display a size-dependency upon the concentration at which the cross-linking reactions are performed.
- Jackson, Alexander W.,Fulton, David A.
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- Optimization of polystyrene-supported triphenylphosphine catalysts for aza-Morita-Baylis-Hillman reactions
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A series of polar group functionalized polystyrene-supported phosphine reagents were examined as catalysts in the aza-Morita-Baylis-Hillman reactions of N-tosyl arylimines and a variety of Michael acceptors with the aim of identifying the optimal polymer/solvent combination. For these reactions JandaJel-PPh3 (1 mmol PPh3/g loading) resin containing methoxy groups (JJ-OMe-PPh3) on the polystyrene backbone in THF solvent provided the highest yield of all the catalyst/solvent combinations examined. The methyl ether groups were incorporated into JJ-OMe-PPh3 using commercially available 4-methoxystyrene, and thus such polar polystyrene resins are easily accessible and should find utility as nucleophilic catalyst supports.
- Zhao, Lin-Jing,Kwong, Cathy Kar-Wing,Shi, Min,Toy, Patrick H.
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- N-Doping of thermally polymerizable fullerenes as an electron transporting layer for inverted polymer solar cells
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A novel [6,6]-phenyl-C61-butyric acid methyl styryl ester (PCBM-S) was synthesized and employed as an electron transporting interfacial layer for bulk heterojunction polymer solar cells with an inverted device configuration. After the deposition of PCBM-S film from solution, the styryl groups of PCBM-S were polymerized by post-thermal treatment to form a robust film which is resistive to common organic solvents. This allows the solution processing of upper bulk heterojunction film without eroding the PCBM-S layer. Additionally, the PCBM-S was n-doped with decamethylcobaltocene (DMC) to increase the conductivity of the film, which resulted in a significantly improved power conversion efficiency from 1.24% to 2.33%. The improved device performance is due to the decrease of series resistance and improved electron extraction property of the n-doped PCBM-S film.
- Cho, Namchul,Yip, Hin-Lap,Hau, Steven K.,Chen, Kung-Shih,Kim, Tae-Wook,Davies, Joshua A.,Zeigler, David F.,Jen, Alex K.-Y.
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- A method of synthesis of alcohols
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The present invention belongs to the field of organic synthesis technology, specifically a synthesis method of an alcohol; the present invention is under the catalytic action of tert-butanol lithium, with ester compounds and pinacol borane as raw materials, tetrahydrofuran as a solvent, reacted at 100 ° C for 24h, followed by adding 2mol / LNaOH / MeOH solution, stirred at room temperature overnight to obtain alcohol compounds; the raw materials of the present invention are of extensive sources or easy to prepare, the reaction conditions are relatively mild and do not require a large number of / cumbersome additives, in addition to the tert-butanol lithium catalyst is simple, And the prepared alcohol compounds are of high quality and high separation yield.
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Paragraph 0079-0084
(2022/01/10)
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- Photoinduced Hydrocarboxylation via Thiol-Catalyzed Delivery of Formate across Activated Alkenes
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Herein we disclose a new photochemical process to prepare carboxylic acids from formate salts and alkenes. This redox-neutral hydrocarboxylation proceeds in high yields across diverse functionalized alkene substrates with excellent regioselectivity. This operationally simple procedure can be readily scaled in batch at low photocatalyst loading (0.01% photocatalyst). Furthermore, this new reaction can leverage commercially available formate carbon isotologues to enable the direct synthesis of isotopically labeled carboxylic acids. Mechanistic studies support the working model involving a thiol-catalyzed radical chain process wherein the atoms from formate are delivered across the alkene substrate via CO2?- as a key reactive intermediate.
- Alektiar, Sara N.,Wickens, Zachary K.
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supporting information
p. 13022 - 13028
(2021/09/03)
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- In-situ facile synthesis novel N-doped thin graphene layer encapsulated Pd@N/C catalyst for semi-hydrogenation of alkynes
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Transition metal-catalyzed semi-hydrogenation of alkynes has become one of the most popular methods for alkene synthesis. Specifically, the noble metal Pd, Rh, and Ru-based heterogeneous catalysts have been widely studied and utilized in both academia and industry. But the supported noble metal catalysts are generally suffering from leaching or aggregation during harsh reaction conditions, which resulting low catalytic reactivity and stability. Herein, we reported the facile synthesis of nitrogen doped graphene encapsulated Pd catalyst and its application in the chemo-selective semi-hydrogenation of alkynes. The graphene layer served as “bulletproof” over the active Pd Nano metal species, which was confirmed by X-ray and TEM analysis, enhanced the catalytic stability during the reaction conditions. The optimized prepared Pd@N/C catalyst showed excellent efficiency in semi-hydrogenation of phenylacetylene and other types of alkynes with un-functionalized or functionalized substituents, including the hydrogenation sensitive functional groups (NO2, ester, and halogen).
- Lin, Shanshan,Liu, Jianguo,Ma, Longlong,Sun, Jiangming
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- Controlling Multiple Active Sites on Pd?CeO2 for Sequential C?C Cross-coupling and Alcohol Oxidation in One Reaction System
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Ceria (CeO2)-supported metal catalysts have been widely utilized for various single-step chemical transformations. However, using such catalysts for a multistep organic reaction in one reaction system has rarely been achieved. Here, we investigate multiple active sites on Pd?CeO2 catalysts and optimize them for a multistep reaction of C?C cross-coupling and alcohol oxidation. Atomic-level imaging and spectroscopic studies reveal that metallic Pd0 and Pd?CeO2 interface are active sites on Pd?CeO2 for C?C cross-coupling and oxidation, respectively. These active sites are controlled under the structural evolution of Pd?CeO2 during reductive heat-treatments. Accordingly, we found that optimally reduced Pd?CeO2 catalysts containing ~1.5 nm-sized Pd nanoclusters with both sites in balance are ideal for multistep chemical transformations in one reaction system. Our strategy to design supported metal catalysts leads to one-pot sequential synthetic protocols for pharmaceutical building blocks.
- Antink, Wytse Hooch,Bok, Jinsol,Cho, Sung-Pyo,Choi, Hyunwoo,Hyeon, Taeghwan,Jung, Yoon,Kim, Do Heui,Kim, Jiheon,Kim, Jongchan,Kim, Ju Hee,Kim, Sumin,Kim, Young Gyu,Ko, Wonjae,Kwak, Minjoon,Lee, Byoung-Hoon,Lee, Chan Woo,Lee, Eunwon,Lee, Kug-Seung,Lee, Seong Chan,Yim, Guk Hee,Yoo, Dongwon
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- Nickel(II) Catalyzed Hydroboration: A Route to Selective Reduction of Aldehydes and N-Allylimines
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A cationic [(iminophosphine)nickel(allyl)]+ complex was found to be sufficiently electrophilic to activate aldehydes and N-allylimines to undergo hydroboration with pinacolborane (HBpin) under mild reaction conditions. The catalyst displayed excellent selectivity toward aldehydes in the presence of ketones. A wide variety of functional groups were tolerated, including halogens, NO2, CN, OMe, and alkenes for both aldehydes and imines. Electron-rich substrates were found to be significantly more reactive than their electron poor counterparts, a feature that was correlated to their enhanced ability to coordinate to the Lewis acidic nickel center.
- Hossain, Istiak,Schmidt, Joseph A. R.
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p. 1877 - 1884
(2020/05/25)
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- Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
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Reversible catalytic reactions operate under thermodynamic control, and thus, establishing a selective catalytic system poses a considerable challenge. Herein, we report a reversible transfer hydrocyanation protocol that exhibits high selectivity for the thermodynamically less favorable branched isomer. Selectivity is achieved by exploiting the lower barrier for C-CN oxidative addition and reductive elimination at benzylic positions in the absence of a cocatalytic Lewis acid. Through the design of a novel type of HCN donor, a practical, branched-selective, HCN-free transfer hydrocyanation was realized. The synthetically useful resolution of a mixture of branched and linear nitrile isomers was also demonstrated to underline the value of reversible and selective transfer reactions. In a broader context, this work demonstrates that high kinetic selectivity can be achieved in reversible transfer reactions, thus opening new horizons for their synthetic applications.
- Bhawal, Benjamin N.,Ehinger, Christian,Morandi, Bill,Reisenbauer, Julia C.
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supporting information
p. 10914 - 10920
(2020/07/13)
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- Nickel-Catalyzed Stereodivergent Synthesis of E- and Z-Alkenes by Hydrogenation of Alkynes
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A convenient protocol for stereodivergent hydrogenation of alkynes to E- and Z-alkenes by using nickel catalysts was developed. Simple Ni(NO3)2?6 H2O as a catalyst precursor formed active nanoparticles, which were effective for the semihydrogenation of several alkynes with high selectivity for the Z-alkene (Z/E>99:1). Upon addition of specific multidentate ligands (triphos, tetraphos), the resulting molecular catalysts were highly selective for the E-alkene products (E/Z>99:1). Mechanistic studies revealed that the Z-alkene-selective catalyst was heterogeneous whereas the E-alkene-selective catalyst was homogeneous. In the latter case, the alkyne was first hydrogenated to a Z-alkene, which was subsequently isomerized to the E-alkene. This proposal was supported by density functional theory calculations. This synthetic methodology was shown to be generally applicable in >40 examples and scalable to multigram-scale experiments.
- Murugesan, Kathiravan,Bheeter, Charles Beromeo,Linnebank, Pim R.,Spannenberg, Anke,Reek, Joost N. H.,Jagadeesh, Rajenahally V.,Beller, Matthias
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p. 3363 - 3369
(2019/06/28)
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- Storing redox equivalent in the phenalenyl backbone towards catalytic multi-electron reduction
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Storing and transferring electrons for multi-electron reduction processes are considered to be the key steps in various important chemical and biological transformations. In this work, we accomplished multi-electron reduction of a carboxylic acid via a hydrosilylation pathway where a redox-active phenalenyl backbone in Co(PLY-O,O)2(THF)2, stores electrons and plays a preponderant role in the entire process. This reduction proceeds by single electron transfer (SET) from the mono-reduced ligand backbone leading to the cleavage of the Si-H bond. Several important intermediates along the catalytic reduction reaction have been isolated and well characterized to prove that the redox equivalent is stored in the form of a C-H bond in the PLY backbone via a ligand dearomatization process. The ligand's extensive participation in storing a hydride equivalent has been conclusively elucidated via a deuterium labelling experiment. This is a rare example where the ligand orchestrates the multielectron reduction process leaving only the metal to maintain the conformational requirements and fine tunes the electronics of the catalyst.
- Bhunia, Mrinal,Sahoo, Sumeet Ranjan,Shaw, Bikash Kumar,Vaidya, Shefali,Pariyar, Anand,Vijaykumar, Gonela,Adhikari, Debashis,Mandal, Swadhin K.
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p. 7433 - 7441
(2019/08/15)
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- Manganese-Catalyzed N-Alkylation of Sulfonamides Using Alcohols
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An efficient manganese-catalyzed N-alkylation of sulfonamides has been developed. This borrowing hydrogen approach employs a well-defined and bench-stable Mn(I) PNP pincer precatalyst, allowing benzylic and simple primary aliphatic alcohols to be employed as alkylating agents. A diverse range of aryl and alkyl sulfonamides undergoes mono-N-alkylation in excellent isolated yields (32 examples, 85% average yield).
- Reed-Berendt, Benjamin G.,Morrill, Louis C.
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p. 3715 - 3724
(2019/03/30)
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- Homogeneous Hydrogenation with a Cobalt/Tetraphosphine Catalyst: A Superior Hydride Donor for Polar Double Bonds and N-Heteroarenes
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The development of catalysts based on earth abundant metals in place of noble metals is becoming a central topic of catalysis. We herein report a cobalt/tetraphosphine complex-catalyzed homogeneous hydrogenation of polar unsaturated compounds using an air- and moisture-stable and scalable precatalyst. By activation with potassium hydroxide, this cobalt system shows both high efficiency (up to 24 000 TON and 12 000 h-1 TOF) and excellent chemoselectivities with various aldehydes, ketones, imines, and even N-heteroarenes. The preference for 1,2-reduction over 1,4-reduction makes this method an efficient way to prepare allylic alcohols and amines. Meanwhile, efficient hydrogenation of the challenging N-heteroarenes is also furnished with excellent functional group tolerance. Mechanistic studies and control experiments demonstrated that a CoIH complex functions as a strong hydride donor in the catalytic cycle. Each cobalt intermediate on the catalytic cycle was characterized, and a plausible outer-sphere mechanism was proposed. Noteworthy, external inorganic base plays multiple roles in this reaction and functions in almost every step of the catalytic cycle.
- Duan, Ya-Nan,Du, Xiaoyong,Cui, Zhikai,Zeng, Yiqun,Liu, Yufeng,Yang, Tilong,Wen, Jialin,Zhang, Xumu
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supporting information
p. 20424 - 20433
(2019/12/27)
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- Metal-Organic Capsules with NADH Mimics as Switchable Selectivity Regulators for Photocatalytic Transfer Hydrogenation
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Switchable selective hydrogenation among the groups in multifunctional compounds is challenging because selective hydrogenation is of great interest in the synthesis of fine chemicals and pharmaceuticals as a result of the importance of key intermediates. Herein, we report a new approach to highly selectively (>99%) reducing C=X (X = O, N) over the thermodynamically more favorable nitro groups locating the substrate in a metal-organic capsule containing NADH active sites. Within the capsule, the NADH active sites reduce the double bonds via a typical 2e- hydride transfer hydrogenation, and the formed excited-state NAD+ mimics oxidize the reductant via two consecutive 1e- processes to regenerate the NADH active sites under illumination. Outside the capsule, nitro groups are highly selectively reduced through a typical 1e- hydrogenation. By combining photoinduced 1e- transfer regeneration outside the cage, both 1e- and 2e- hydrogenation can be switched controllably by varying the concentrations of the substrates and the redox potential of electron donors. This promising alternative approach, which could proceed under mild reaction conditions and use easy-to-handle hydrogen donors with enhanced high selectivity toward different groups, is based on the localization and differentiation of the 2e- and 1e- hydrogenation pathways inside and outside the capsules, provides a deep comprehension of photocatalytic microscopic reaction processes, and will allow the design and optimization of catalysts. We demonstrate the advantage of this method over typical hydrogenation that involves specific activation via well-modified catalytic sites and present results on the high, well-controlled, and switchable selectivity for the hydrogenation of a variety of substituted and bifunctional aldehydes, ketones, and imines.
- Wei, Jianwei,Zhao, Liang,He, Cheng,Zheng, Sijia,Reek, Joost N. H.,Duan, Chunying
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p. 12707 - 12716
(2019/09/04)
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- Monodisperse nickel-nanoparticles for stereo- and chemoselective hydrogenation of alkynes to alkenes
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Here, we report the use of monosaccharides for the preparation of novel nickel nanoparticles (NP), which constitute selective hydrogenation catalysts. For example, immobilization of fructose and Ni(OAc)2 on silica and subsequent pyrolysis under inert atmosphere produced graphitic shells encapsulated Ni-NP with uniform size and distribution. Interestingly, fructose acts as structure controlling compound to generate specific graphitic layers and the formation of monodisperse NP. The resulting stable and reusable catalysts allow for stereo- and chemoselective semihydrogenation of functionalized and structurally diverse alkynes in high yields and selectivity.
- Murugesan, Kathiravan,Alshammari, Ahmad S.,Sohail, Manzar,Beller, Matthias,Jagadeesh, Rajenahally V.
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p. 372 - 377
(2019/01/26)
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- Photoredox generation of the trifluoromethyl radical from borate complexes: Via single electron reduction
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A method for the generation of the CF3 radical from CF3-substituted borate complexes bearing a pyridine-N-oxide ligand is described. Cleavage of the C-B bond occurs via single electron reduction by a Cu(i) photocatalyst activated by visible light.
- Smirnov, Vladimir O.,Maslov, Anton S.,Kokorekin, Vladimir A.,Korlyukov, Alexander A.,Dilman, Alexander D.
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p. 2236 - 2239
(2018/03/06)
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- Direct β-Selective Hydrocarboxylation of Styrenes with CO2 Enabled by Continuous Flow Photoredox Catalysis
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The direct β-selective hydrocarboxylation of styrenes under atmospheric pressure of CO2 has been developed using photoredox catalysis in continuous flow. The scope of this methodology was demonstrated with a range of functionalized terminal styrenes, as well as α-substituted and β-substituted styrenes.
- Seo, Hyowon,Liu, Aofei,Jamison, Timothy F.
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supporting information
p. 13969 - 13972
(2017/10/17)
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- ELECTRORESPONSIVE TECHNOLOGY
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A styrene based water soluble polymer containing pendant sulfonated calix[4]arene groups has been synthesized by using free radical polymerization combined with post-polymerization sulfonation chemistry. The monomer 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene was prepared in 3 steps: (1) reduction of 4-vinyl benzoic acid to the respective alcohol (2) formation of the bromide by the Appel reaction and (3) synthesis of the respective ether by Williamson O-alkylation reaction with calix[4]arene. Polymerization was accomplished by azobisisobutyronitrile (AIBN) initiated free radical polymerization technique. Electro-responsive properties of the sulfonated polymer were studied wherein a response to electrochemical stimulus is observed when guest molecules of methyl viologen are incorporated with polymerized 25-(4-vinylbenzy1)-26, 27, 28-hydroxy-calix[4]arene.
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Page/Page column 10-11
(2015/06/03)
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- Organoborane-Catalyzed Hydrogenation of Unactivated Aldehydes with a Hantzsch Ester as a Synthetic NAD(P)H Analogue
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We have developed a method for the hydrogenation of unactivated aldehydes, using a Hantzsch ester as a NAD(P)H analogue in the presence of an electron-deficient triarylborane as a Lewis acid catalyst. Thus, tris[3,5-bis(trifluoromethyl)phenyl]borane efficiently catalyzes the hydrogenation of aliphatic aldehydes with a Hantzsch ester in 1,4-dioxane at 100 °C to give the corresponding aliphatic primary alcohols in up to 97% yield. Aromatic aldehydes also undergo the hydrogenation, even at 25 °C, to furnish the corresponding aromatic primary alcohols in up to 100% yield.
- Hamasaka, Go,Tsuji, Hiroaki,Uozumi, Yasuhiro
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supporting information
p. 2037 - 2041
(2015/09/01)
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- Electrochemical responsive arrays of sulfonatocalixarene groups prepared by free radical polymerization
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A styrene based water soluble polymer containing pendant sulfonated calix[4]arene groups has been synthesized by using free radical polymerization combined with post-polymerization sulfonation chemistry. The monomer 25-(4-vinylbenzyl)-26, 27, 28-hydroxy-calix[4]arene (VBC4A) was prepared in 3 steps: (1) reduction of 4-vinyl benzoic acid to the respective alcohol (2) formation of the bromide by the Appel reaction and (3) synthesis of the respective ether by Williamson O-alkylation reaction with calix[4]arene. Polymerization was accomplished by azobisisobutyronitrile (AIBN) initiated free radical polymerization technique to afford P(VBC4A) with Mn value of 7090 g/mol and moderate polydispersity. The resulting P(VBC4A) was subsequently reacted with acetyl sulfate to afforded the sulfonated polymer. The reaction was followed by nuclear magnetic resonance and infrared spectroscopy, and the results suggest that the sulfonation reaction lead to nearly quantitative functionalization of the calixarene functional polymer. Elemental analysis by X-ray photoelectron spectroscopy confirmed these findings on the degree of sulfonated functionalization. Electro-responsive properties of the sulfonated polymer were studied by cyclic voltammetry and isothermal titration calorimetry in phosphate buffer saline solution. A response to electrochemical stimulus is observed where guest molecules of methyl viologen incorporate and dissociate with P(VBSC4A).
- Balami, Uddhav,Taylor, Darlene K.
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- Redox-selective generation of aldehydes and H2 from alcohols under visible light
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Photosynthetic dehydrogenation: Potential usefulness of visible-light-induced dehydrogenation of alcohols in organic synthesis was demonstrated, in which aldehydes and H2 were afforded by using Ru/SrTiO3:Rh and water (see scheme). Water was essential for the reaction. High efficiency (TON: up to 15 400 based on Rh; H2 and aldehyde evenly generated) and high selectivity were achieved. Copyright
- Liu, Zijun,Caner, Joaquim,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 9452 - 9456
(2013/07/26)
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- Isoxazolines as Therapeutic Agents
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The present invention provides compound of Formula (I) biologically active metabolites, pro-drugs, isomers, stereoisomers, solvates, hydrates and pharmaceutically acceptable salts thereof wherein the variables are defined herein. The compounds of the invention are useful for treating immunological conditions.
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Paragraph 0909
(2013/03/26)
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- Flow Chemistry Syntheses of Styrenes, Unsymmetrical Stilbenes and Branched Aldehydes
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Two tandem flow chemistry processes have been developed. A single palladium-catalysed Heck reaction with ethylene gas provides an efficient synthesis for functionalised styrenes. Through further elaboration the catalyst becomes multi-functional and performs a second Heck reaction providing a single continuous process for the synthesis of unsymmetrical stilbenes. In addition, the continuous, rhodium-catalysed, hydroformylation of styrene derivatives with syngas affords branched aldehydes with good selectivity. Incorporation of an in-line aqueous wash and liquid-liquid separation allowed for the ethylene Heck reaction to be telescoped into the hydroformylation step such that a single flow synthesis of branched aldehydes directly from aryl iodides was achieved. The tube-in-tube semi-permeable membrane-based gas reactor and liquid-liquid separator both play an essential role in enabling these telescoped flow processes.
- Bourne, Samuel L.,O'Brien, Matthew,Kasinathan, Sivarajan,Koos, Peter,Tolstoy, Paeivi,Hu, Dennis X.,Bates, Roderick W.,Martin, Benjamin,Schenkel, Berthold,Ley, Steven V.
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p. 159 - 172
(2013/03/13)
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- Nitroxide-mediated controlled radical polymerizations of styrene derivatives
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Several (protected) amine and alcohol functionalized styrene monomers were synthesized via readily accessible synthetic routes. The controlled radical copolymerization of these functionalized styrene monomers with styrene was performed using two alkoxyamines, namely N-(2-methylpropyl)-N-(1- diethylphosphono-2,2-dimethylpropyl)-O-(2-carboxylprop-2-yl) hydroxylamine (MAMA-SG1) and N-tert-butyl-N-(2-methyl-1-phenylpropyl)-O-(1-phenylethyl) hydroxylamine. The copolymers obtained showed low polydispersities, controlled molecular weights, and a random topology. The thermal properties of the polymers were determined with differential scanning calorimetry. All polymers were amorphous and showed glass transition temperatures between 40 and 111 °C. Deprotection of the copolymers afforded amine or alcohol pendant polystyrenes which were readily functionalized with isocyanates.
- Stals, Patrick J. M.,Phan, Trang N. T.,Gigmes, Didier,Paffen, Tim F. E.,Meijer,Palmans, Anja R. A.
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experimental part
p. 780 - 791
(2012/05/19)
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- Palladium-catalyzed heck-type reactions of alkyl iodides
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A palladium-catalyzed Heck-type reaction of unactivated alkyl iodides is described. This process displays broad substrate scope with respect to both alkene and alkyl iodide components and provides efficient access to a variety of cyclic products. The reaction is proposed to proceed via a hybrid organometallic-radical mechanism, facilitating the Heck-type process with alkyl halide coupling partners. Initial intermolecular studies are also reported, demonstrating the potentially wide applicability of this approach in synthesis.
- Bloome, Kayla S.,McMahen, Rebecca L.,Alexanian, Erik J.
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supporting information; experimental part
p. 20146 - 20148
(2012/02/01)
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- Synthesis and characterization of cross-linkable ruthenium dye with ion coordinating property for dye-sensitized solar cells
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Crosslinkable ruthenium complex dye, Ru(2,2′-bipyridine-4,4′- bicarboxylic acid)(4,4′-bis((4-vinyl benzyloxy)methyl)-2,2′- bipyridine)(NCS)2 (denoted as Ru-S dye), was synthesized and characterized using 1H-NMR, 13C-NMR, Fourier transform infrared (FTIR) and UV/vis spectroscopies.The power conversion efficiency of dye-sentitized solar cell (DSSC) using Ru-S and liquid electrolyte containing lithium iodide (LiI) reached 7.53% under standard global AM 1.5 full sunlight, which is partly attributed to Li+ being coordinated by Ru-S as verified by ATR-FTIR spectroscopy. As Ru-S was further crosslinked with glycerol propoxylate triacrylate (GPTA), not only 89% of dye retained on TiO2 mesoporous surface after rinsed by 0.1 N NaOH aqueous solution, the power efficiency was also increased to 7.88%. As poly(methyl acrylate) was used to gel the electrolyte system, the power efficiency of DSSC with Ru-S dye was 6.96% but increased to 7.57% after crosslinking with GPTA. Notably, both DSSCs showed a good long-term stability after one month storage.
- Liu, Ken-Yen,Ko, Chih-Yang,Ho, Kuo-Chuan,Lin, King-Fu
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scheme or table
p. 3318 - 3324
(2012/05/31)
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- The continuous-flow synthesis of styrenes using ethylene in a palladium-catalysed heck cross-coupling reaction
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We report a palladium-catalysed ethylene Heck reaction for the vinylation of aryl iodides using a tube-in-tube gas-liquid reactor. The flow process afforded various styrenes in short reaction times, employing moderate ethylene pressure. Georg Thieme Verlag Stuttgart · New York.
- Bourne, Samuel L.,Koos, Peter,Obrien, Matthew,Martin, Benjamin,Schenkel, Berthold,Baxendale, Ian R.,Ley, Steven V.
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scheme or table
p. 2643 - 2647
(2011/12/04)
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- Polyhedral oligomeric silsesquioxane-based fluoroether-containing terpolymers: Synthesis, characterization and their water and oil repellency evaluation for cotton fabric
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A series of polyhedral oligomeric silsesquioxane (POSS) based hybrid copolymers poly(POSS-co-methyl methacrylate -co- 4-vinylbenzyl fluoroether carboxylate) (P(POSS-MMA-VBFC)) were prepared via radical polymerization and characterized by nuclear magnetic resonance, fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, gel permeation chromatography, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. The thermal properties of these polymers (Td > 250 °C) were improved by the introduction of POSS cage. The cotton fabrics coated with the polymers possessed excellent water and oil repellency. The water and salad oil contact angle could be achieved from 133° to 159° and from 127° to 141° respectively as the content of POSS in the polymer increased from 0 to 7.1 wt %. Moreover, the cotton fabric coated with the terpolymer was less flammable than the uncoated one.
- Gao, Yu,He, Chuanglong,Qing, Feng-Ling
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experimental part
p. 5152 - 5161
(2012/07/14)
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- Revisiting the Meerwein-Ponndorf-Verley reduction: A sustainable protocol for transfer hydrogenation of aldehydes and ketones
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An economical and sustainable transfer hydrogenation for aldehydes and ketones is described. The general protocol is mild, chemo-selective and, importantly, uses neither precious nor non-precious metals and even no ligands. The Royal Society of Chemistry 2009.
- Polshettiwar, Vivek,Varma, Rajender S.
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experimental part
p. 1313 - 1316
(2010/05/02)
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- Palladium-catalyzed markovnikov terminal arylalkynes hydrostannation: Application to the synthesis of 1,1-diarylethylenes
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The palladium-catalyzed hydrostannation of terminal aryla-lkynes was achieved. The regioselectivity of the H-Sn bond addition across the triple bond was found to be controlled by an ortho substituent on the aromatic ring, whatever its electronic nature, to give exclusively α-branched vinylstan-nanes 2 in accordance with Markovnikov's rule. Subsequent Stille cross-coupling reaction of 2 with a variety of aryl halides readily provided, in moderate to good yields, a family of functionalized 1,1-diarylethylenes 1.
- Hamze, Abdallah,Veau, Damien,Provot, Olivier,Brion, Jean-Daniel,Alami, Mouad
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scheme or table
p. 1337 - 1340
(2009/07/04)
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- Ruthenium-catalyzed, one-pot alcohol oxidation-wittig reaction producing αβ unsaturated esters
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By a one-pot process, αβ-unsaturated esters were synthesized in high yield through the Ru-catalyzed oxidation of primary alcohols and the coupling of the resulting aldehydes and stabilized Wittig reagents. The ruthenium catalyst is composed of ruthenium nanoparticles embedded in aluminum oxyhydroxide and can be recovered simply by filtration or decantation. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
- Lee, Eun Young,Kim, Youngkwon,Lee, Jae Sung,Park, Jaiwook
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supporting information; experimental part
p. 2943 - 2946
(2009/10/11)
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- Polymer-supported hantzsch 1,4-dihydropyridine ester: An efficient biomimetic hydrogen source
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An efficient synthesis of a polymer-supported Hantzsch 1,4-dihydropyridine ester has been developed and its use in a variety of reduction reactions was studied using α,β-unsaturated aldehydes, imines and an activated benzoquinone as substrates. Reductive amination using the polymer-supported Hantzsch 1,4-dihydropyridine ester and a catalytic amount of 1.5 M HCl was found to proceed rapidly and with good yields.
- He, Rongjun,Toy, Patrick H.,Lam, Yulin
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experimental part
p. 54 - 60
(2009/04/07)
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- Vinylation of aryl bromides using an inexpensive vinylpolysiloxane
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(Chemical Equation Presented) A mild and general method for the palladium-catalyzed vinylation of aryl bromides has been developed. The use of tetrabutylammonium fluoride (TBAF) as the activator and an inexpensive and nontoxic vinyl donor, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4V, 1), allows for a general and high-yielding preparation of substituted styrenes.
- Denmark, Scott E.,Butler, Christopher R.
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- Suzuki-Miyaura cross-coupling reactions of potassium vinyltrifluoroborate with aryl and heteroaryl electrophiles
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We have previously reported that the palladium-catalyzed cross-coupling reaction of potassium vinyltrifluoroborate with aryl electrophiles proceeds with good yields. Herein, we describe recent progress in optimizing the reaction, as well as outlining the scope and limitations of the reaction. The cross-coupling reaction can generally be effected using 2 mol % of PdCl2 and 6 mol % of PPh3 as a catalyst system in THF/H2O with Cs 2CO3 as a base. Moderate to good yields are obtained in the presence of a variety of functional groups.
- Molander, Gary A.,Brown, Adam R.
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p. 9681 - 9686
(2007/10/03)
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- Synthesis and color tuning properties of blue highly fluorescent vinyl polymers containing a pendant pyrrolopyridazine
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We report here the synthesis, polymerization, and properties of highly fluorescent vinyl polymers containing pendant pyrrolopyridazines. Their luminescence quantum efficiencies can be as high as 60%, and all polymers showed strong luminescence even in the solid state, which is indicative of little self-quenching in these systems. The polymers were processable into films, fibers, and rods that were suitable for several device applications. The fibers and rods showed interesting end luminescence whose colors were tunable by manipulating their geometries.
- Mitsumori, Teruyuki,Craig, Ian M.,Martini, Ignacio B.,Schwartz, Benjamin J.,Wudl, Fred
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p. 4698 - 4704
(2007/10/03)
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- A new and facile method for stereoselective synthesis of (E)-styryl bromides by the reduction of 1,1-dibromoalkenes using LiAlH4-EtOAc (1:1)
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A facile method for stereoselective synthesis of (E)-styryl bromides by the reduction of 1,1-dibromoalkenes using LiAlH4-EtOAc (1:1) is described. We believe that the present procedure is a good alternative to the Tokuda's microwave method with good stereoselectivity.
- Horibe, Hideo,Kondo, Kazuhiro,Okuno, Hiroaki,Aoyama, Toyohiko
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p. 986 - 988
(2007/10/03)
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- Carboxy containing monomers
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Certain ethylenically unsaturated polymerizable monomers having a reactive carboxy group are useful for preparing homo- and copolymers for a variety of uses, including diagnostic assays. The polymers can be supplied as latex particles in aqueous compositions. The monomers are represented by the structure: STR1 wherein: R is hydrogen, halo or alkyl of 1 to 3 carbon atoms, M is hydrogen, an alkali metal ion or an ammonium ion, and L is a linking group having from 8 to 50 atoms in its linking chain, and comprises two or more divalent hydrocarbon groups connected or terminated with one or more nitrogen, oxygen or sulfur atoms, or with one or more groups containing such atoms in the linking chain, provided L has at least one arylene which is not directly connected to the terminal STR2 group, and further provided that none of the hydrocarbon groups has non-aromatic unsaturation.
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