- Convenient synthesis of thermo-responsive PtBA-g-PPEGMEMA well-defined amphiphilic graft copolymer without polymeric functional group transformation
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A series of well-defined amphiphilic graft copolymers bearing hydrophobic poly(tert-butyl acrylate) backbone and hydrophilic poly[poly(ethylene glycol) methyl ether methacrylate)] (PPEGMEMA) side chains were synthesized by sequential reversible addition fragmentation chain transfer (RAFT) polymerization and single-electron-transfer living radical polymerization (SET-LRP) without any polymeric functional group transformation. A new Br-containing acrylate monomer, tert-butyl 2-((2-bromoisobutanoyloxy)methyl) acrylate (tBBIBMA), was first prepared, which can be homopolymerized by RAFT to give a well-defined PtBBIBMA homopolymer with a narrow molecular weight distribution (Mw/Mn = 1.15). This homopolymer with pendant Br initiation group in every repeating unit initiated SET-LRP of PEGMEMA at 45 °C using CuBr/dHbpy as catalytic system to afford well-defined PtBBIBMA-g-PPEGMEMA graft copolymers via the grafting-from strategy. The self-assembly behavior of the obtained graft copolymers in aqueous media was investigated by fluorescence spectroscopy and TEM. These copolymers were found to be stimuli-responsive to both temperature and ions. Finally, poly(acrylic acid)-g-PPEGMEMA double hydrophilic graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PPEGMEMA side chains kept inert.
- Song, Xuemei,Zhang, Yaqin,Yang, Dong,Yuan, Li,Hu, Jianhua,Lu, Guolin,Huang, Xiaoyu
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- PAA-g-PPO amphiphilic graft copolymer: Synthesis and diverse micellar morphologies
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A series of well-defined amphiphilic graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer nitroxide radical coupling (ATNRC) chemistry followed by selective hydrolysis of poly(tert-buty1 acrylate) backbone. A new Br- containing acrylate monomer, tert-butyl 2-((2-bromopropanoyloxy)methyl) acrylate, was first prepared, and it can be polymerized via RAFT in a controlled way to obtain a well-defined homopolymer with narrow molecular weight distribution {MwMn = 1.06). Grafting-onto strategy was employed to synthesize PiBA-gPPO well-defined graft copolymers with narrow molecular weight distributions {MwM n = 1.05-1.23) via ATNRC reaction between Br-containing PiBA-based backbone and poly(propylene oxide) with 2, 2, 6, 6-tetramethylpiperidine-l-oxyl (TEMPO) end group using CuBr/PMDETA or Cu/PMDETA as catalytic system. The final PAA-g-PPO amphiphilic graft copolymers were obtained by the selective acidic hydrolysis of PrBA backbone in acidic environment without affecting the side chains. The critical micelle concentrations in aqueous media were determined by a fluorescence probe technique. Diverse micellar morphologies were formed with varying the content of hydrophobic PPO segment.
- Li, Yaogong,Zhang, Yaqin,Yang, Dong,Li, Yongjun,Hu, Jianhua,Feng, Chun,Zhai, Sujuan,Lu, Guolin,Huang, Xiaoyu
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- ATNRC and SET-NRC synthesis of PtBA-g-PEO well-defined amphiphilic graft copolymers
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A series of new well-defined amphiphilic graft copolymers containing hydrophobic poly(tert-butyl acrylate) backbone and hydrophilic poly(ethylene oxide) side chains were reported. Reversible addition-fragmentation chain transfer homopolymerization of tert-butyl 2-((2-bromopropanoyloxy)methyl) acrylate was first performed to afford a well-defined backbone with a narrow molecular weight distribution (Mw/Mn = 1.07). The target poly(tert-butyl acrylate)-g-poly(ethylene oxide) (PtBA-g-PEO) graft copolymers with low polydispersities (Mw/Mn = 1.18-1.26) were then synthesized by atom transfer nitroxide radical coupling or single electron transfer-nitroxide radical coupling reaction using CuBr(Cu)/PMDETA as catalytic system. Fluorescence probe technique was employed to determine the critical micelle concentrations (cmc) of the obtained amphiphilic graft copolymers in aqueous media. Furthermore, PAA-g-PEO graft copolymers were obtained by selective acidic hydrolysis of hydrophobic PtBA backbone while PEO side chains kept inert.
- Li, Yaogong,Du, Ming,Zhang, Yaqin,Li, Yongjun,Sui, Long,Lu, Guolin,Huang, Xiaoyu
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- Synthesis of PAA-g-PNIPAM well-defined graft polymer by sequential RAFT and SET-LRP and its application in preparing size-controlled super-paramagnetic Fe3O4 nanoparticles as a stabilizer
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A series of well-defined double hydrophilic graft copolymers, poly(acrylic acid)-g-poly(N-isopropylacrylamide) (PAA-g-PNIPAM), was employed as a novel water-soluble coating for constructing superparamagnetic iron oxide nanoparticles. The copolymer was synthesized via a three-step procedure: firstly, a well-defined hydrophobic PtBA-based backbone, poly(tert-butyl 2-((2-chloropropanoyloxy)-methyl)acrylate)-co-poly(tert-butyl acrylate), (PtBCPMA19-co-PtBA18), was prepared through RAFT copolymerization of a new trifunctional acrylic monomer, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate and tert-butyl acrylate; secondly, taking this backbone as a macroinitiator to initiate SET-LRP of N-isopropylacrylamide resulted in well-defined (poly(tert-butyl 2-((2-chloropropanoyloxy)methyl)-acrylate)-co-poly(tert-butyl acrylate))-g-poly(N-isopropylacrylamide) ((PtBCPMA-co-PtBA)-g-PNIPAM) amphiphilic graft copolymers with relatively narrow polydispersities (M w/Mn ≤ 1.31); thirdly, handling (PtBCPMA-co-PtBA)-g- PNIPAM in acidic conditions afforded PAA-g-PNIPAM graft copolymers. The resulting PAA-g-PNIPAM copolymers were directly utilized as a polymeric stabilizer in the preparation of superparamagnetic Fe3O4 nanoparticles. The particle size can be readily tuned in the range of 12.1-23.2 nm by varying the amount of PAA-g-PNIPAM copolymer or the length of PNIPAM side chain. Besides, the structure and properties of prepared Fe3O 4/polymer nanocomposites were characterized by XRD, FT-IR, TGA, TEM, and magnetic measurement in detail.
- Jiang, Xiuyu,Zhai, Sujuan,Jiang, Xue,Lu, Guolin,Huang, Xiaoyu
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- Convenient synthesis of PtBA-g-PMA well-defined graft copolymer with tunable grafting density
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A series of well-defined graft copolymers, consisting of poly(tert-butyl acrylate) backbone and poly (methyl acrylate) side chains, were synthesized by the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). A new acrylate monomer containing ATRP initiation group, tert-butyl 2-((2-bromopropanoyloxy) methyl)acrylate, was first prepared, which can be homopolymerized or copolymerized with tert-butyl acrylate by RAFT in a controlled way to obtain well-defined homopolymers and copolymers with narrow molecular weight distributions (Mw/Mn w/Mn 1.28) with controllable grafting densities via the grafting-from strategy without any polymeric functional group transformation. Finally, the poly(tert-butyl acrylate) backbone was selectively hydrolyzed in acidic environment without affecting the poly(methyl acrylate) side chains to give poly(acrylic acid)-g-poly(methyl acrylate) amphiphilic graft copolymers
- Zhang, Yaqin,Shen, Zhong,Yang, Dong,Feng, Chun,Hu, Jianhua,Lu, Guolin,Huang, Xiaoyu
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- Bicyclo[3.2.0]heptane as a Core Structure for Conformational Locking of 1,3-Bis-Pharmacophores, Exemplified by GABA
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The synthesis and X-ray crystal structures of syn and anti 4-N-Boc-aminobicyclo[3.2.0]heptane-1-carboxylic acids are described. The placement of the N-Boc-amino groups in the two stereoisomers in either pseudo-equatorial or pseudo-axial positions renders the molecules conformationally locked, with N-Boc-protected γ-aminobutyric acid (GABA) embedded within the bicyclic core. Despite the different conformations of the urethane and distinct crystal packing, the bicyclic core units of the two stereoisomers adopt virtually identical structures. They correspond to in silico models of the parent bicyclic core and a systematic array of disubstituted derivatives. The study documents an intrinsic property of the bicyclo[3.2.0]heptane core to favor adoption of a boat-like conformation, which is largely unaffected by various substitution patterns. The structural concepts are useful in the design of molecules with spatial and directional fixation of pharmacophoric groups.
- Vorberg, Raffael,Trapp, Nils,Carreira, Erick M.,Müller, Klaus
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- Synthesis of starlike PtBA-g-PEO amphiphilic graft copolymer via highly efficient Cu-catalyzed SET-NRC reaction at ambient temperature
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Two new amphiphilic star graft copolymers bearing hydrophobic poly(tert-butyl acrylate) backbone and hydrophilic poly(ethylene oxide) (PEO) side chains with different molecular weights were synthesized by sequential reversible addition fragmentation chain
- Li, Yaogong,Zhang, Yaqin,Zhai, Sujuan,Deng, Yan,Xiong, Huiming,Lu, Guolin,Huang, Xiaoyu
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- Synthesis of PAA-g-PNVCL Graft Copolymer and Studies on Its Loading of Ornidazole
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A well-defined amphiphilic graft copolymer, consisting of hydrophobic poly(tert-butyl acrylate) (PtBA) backbone and hydrophilic poly(N-vinylcaprolactam) (PNVCL) side chains, was synthesized by successive reversible addition-fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP). A new acrylate monomer bearing a chlorine-based initiating group, tert-butyl 2-((2-chloropropanoyloxy)methyl)acrylate, was first RAFT homopolymerized in a controlled way to give a well-defined homopolymer with a narrow molecular weight distribution (Mw/Mn=1.15). This homopolymer directly initiated ATRP of N-vinylcaprolactam (NVCL) to afford a well-defined PtBA-g-PNVCL graft copolymer (Mw/Mn=1.22) via the grafting-from strategy without polymeric functionality transformation. PAA-g-PNVCL graft copolymer was prepared by selectively hydrolyzing PtBA-g-PNVCL. Ornidazole (ONZ)-loaded polymeric micelles using PAA-g-PNVCL copolymer as carrier were prepared by physical entrapping. Drug release experiment of the nano-carrier indicated the pH-dependent drug release characteristics.
- Qian, Wenhao,Xu, Peicheng,Lu, Guolin,Huang, Xiaoyu
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- Metal-free access to 3-allyl-2-alkoxychromanonesviaphosphine-catalyzed alkoxy allylation of chromones with MBH carbonates and alcohols
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A metal-free access to 3-allyl-2-alkoxychromanones by PPh3-catalyzed alkoxy allylation of chromones with MBH carbonates and alcohols is described. This reaction is performed under mild conditions and it shows good functional group tolerance, providing a series of functionalized chromanones in moderate to high yields with excellent diastereoselectivities. Deuterium-labeling experiments to probe a possible mechanism and scale-up reaction were also conducted.
- Meng, Ling,Chang, Xiaoyong,Lin, Zhenyang,Wang, Jun (Joelle)
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supporting information
p. 2663 - 2667
(2021/04/07)
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- Copper-catalyzed radical oxyallylation of olefins for the construction of alkene-containing isoxazolines
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A radical-mediated approach to alkene oxyallylation using allylic oximes is described. The reaction proceeds under copper-catalytic redox-neutral conditions and tolerates various functional groups. This protocol thus enables the synthesis of structurally valuable isoxazolines and the introduction of a versatile olefin motif in a single step.
- He, Xiaoxue,Qian, Lijie,Dai, Yuyu,Yan, Xinhuan,Li, Xiaoqing,Xu, Xiangsheng
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supporting information
(2021/05/31)
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- Phosphine-Catalyzed Cascade Annulation of MBH Carbonates and Diazenes: Synthesis of Hexahydrocyclopenta[c]pyrazole Derivatives
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A phosphine-catalyzed cascade annulation of Morita-Baylis-Hillman (MBH) carbonates and diazenes was achieved, giving tetrahydropyrazole-fused heterocycles bearing two five-membered rings in moderate to excellent yields. The reaction underwent an unprecedented reaction mode of MBH carbonates, in which two molecules of MBH carbonates were fully merged into the ring system.
- Guo, Hongchao,Li, Hongxiang,Liu, Hao,Shi, Wangyu,Wang, Chang,Wang, Wei,Wu, Yongjun
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supporting information
p. 5571 - 5575
(2021/07/31)
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- Branched Aggregates with Tunable Morphology via Hierarchical Self-Assembly of Azobenzene-Derived Molecular Double Brushes
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Hierarchical self-assembly is one of the most effective approaches to fabricate nature-inspired materials with subtle nanostructures. We report a distinct hierarchical self-assembly process of molecular double brushes (MDBs) with each graft site carrying
- Lin, Shaoliang,Qian, Hongyu,Xu, Binbin,Zhang, Ling
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supporting information
p. 17707 - 17713
(2021/07/12)
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- Copper-Catalyzed Intermolecular Alkynylation and Allylation of Unactivated C(sp3)-H Bonds via Hydrogen Atom Transfer
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We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp3)-H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing N-fluoro-sulfonamide as a HAT reagent, a set of subst
- Liang, Lei,Guo, Ge,Li, Chen,Wang, Song-Lin,Wang, Yue-Hui,Guo, Hai-Ming,Niu, Hong-Ying
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supporting information
p. 8575 - 8579
(2021/11/13)
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- Photoredox-Coupled F-Nucleophilic Addition: Allylation of gem-Difluoroalkenes
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A novel strategy for the expedient construction of CF3-embeded tertiary/quarternary carbon centers was developed by taking advantage of photoredox catalysis. Thanks to a key step of single-electron oxidation, electron-rich gem-difluoroalkenes, which otherwise are essentially reluctant towards F-nucleoplilic addition, now readily participate in this fluoroallylation reaction. Furthermore, this strategy provides an elegant example for the generation, as well as functionalization, of α-CF3-substituted benzylic radical intermediates using cheap and readily available starting materials.
- Liu, Haidong,Ge, Liang,Wang, Ding-Xing,Chen, Nan,Feng, Chao
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supporting information
p. 3918 - 3922
(2019/02/19)
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- Enantioselective dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita-Baylis-Hillman carbonates
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The phosphine-catalyzed asymmetric dearomative [3+2] cycloaddition of 2-nitrobenzofurans with aldehyde-derived Morita-Baylis-Hillman (MBH) carbonates or allenoate was developed. The reaction with MBH carbonates resulted in a series of cyclopentabenzofurans containing three contiguous stereocenters with good to high yields, diastereoselectivities and enantioselectivities. The use of allenoate also gave the target product with moderate enantioselectivity.
- Yang, Xin-He,Li, Jian-Ping,Wang, Dong-Chao,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming
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supporting information
p. 9144 - 9147
(2019/08/07)
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- N-Heterocyclic Carbene Catalyzed (5+1) Annulations Exploiting a Vinyl Dianion Synthon Strategy
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Direct polarity inversion of conjugate acceptors provides a valuable entry to homoenolates. N-heterocyclic carbene (NHC) catalyzed reactions, in which β-unsubstituted conjugate acceptors undergo homoenolate formation and C?C bond formation twice, have been developed. Specifically, the all-carbon (5+1) annulations give a range of mono- and bicyclic cyclohexanones (31 examples). In the first family of annulations, β-unsubstituted acrylates tethered to a divinyl ketone undergo cycloisomerization, providing hexahydroindenes and tetralins. In the second, partially untethered substrates undergo an intermolecular (5+1) annulation involving dimerization followed by cycloisomerization. While enantioselectivity was not possible with the former, the latter proved viable, allowing cyclohexanones to be produced with high levels of enantiopurity (most >95:5 e.r.) and exclusive diastereoselectivity (>20:1 d.r.). Derivatizations and mechanistic studies are also reported.
- Nguyen, Xuan B.,Nakano, Yuji,Duggan, Nisharnthi M.,Scott, Lydia,Breugst, Martin,Lupton, David W.
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supporting information
p. 11483 - 11490
(2019/07/18)
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- Photoredox-Catalyzed Cyclopropanation of 1,1-Disubstituted Alkenes via Radical-Polar Crossover Process
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The photoredox-neutral catalyzed cyclopropanation of 1,1-disubstituted alkenes via radical addition-anionic cyclization cascade has been successfully developed. Another new protocol based on photocatalytic allylation and cyclopropanation cascade was also described between allylic halide and halomethyl radical. In addition to the successful use of bis-catecholato silicates as the alkyl radical precursors, the acyl and alkyl radicals derived from 1,4-dihydropyridines were also engaged in this radical-polar crossover process. The competing experiments displayed that the 3-exo-tet mode of cyclization preferred over 4-exo and 5-exo cyclization modes, allowing for the selective 3-exo-tet cyclization. The superior nucleofuge character of bromide over chloride and tosylate has been demonstrated in the reaction of bromomethyl radical with homoallylic (pseudo)halides. This new protocol is characterized by its redox-neutral process, broad substrate scope, mild conditions, and good functional-group compatibility. (Figure presented.).
- Luo, Wenping,Yang, Yi,Fang, Yewen,Zhang, Xinxin,Jin, Xiaoping,Zhao, Guicai,Zhang, Li,Li, Yan,Zhou, Wanli,Xia, Tingting,Chen, Bin
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supporting information
p. 4215 - 4221
(2019/08/16)
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- α-(HALOMETHYL)ACRYLIC COMPOUND, POLYMER, PRODUCTION METHOD THEREFOR, PRODUCTION METHOD FOR HARDENED MATERIAL, AND HARDENED MATERIAL
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PROBLEM TO BE SOLVED: To provide an α-(halomethyl)acrylic compound capable of copolymerizing with an existing electrophilic monomer without applying a particular polymerization condition, to provide a polymer using the α-(halomethyl)acrylic compound, and to provide a method for production of the polymer. SOLUTION: There is provided an α-(halomethyl)acrylic compound represented by a belowmentioned general formula (1) (in the general formula, R1, R2 are each independently hydrogen, an alkyl group or a phenyl group; R is a halogen atom, a tosyl group or a mesityl group; X is an n-valent linkage group; and n is a natural number of 2 to 4). SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0053
(2018/10/10)
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- Stereocontrolled Total Synthesis of (?)-Stemaphylline
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Homologation of readily available α-boryl pyrrolidines with metal carbenoids is especially challenging even when good leaving groups (Cl?) are employed. By performing a solvent switch from Et2O to CHCl3, efficient 1,2-metalate rearrangement of the intermediate boronate occurs with both halide and ester leaving groups. The methodology was used in the total synthesis of the Stemona alkaloid (?)-stemaphylline in just 11 steps (longest linear sequence), with high stereocontrol (>20:1 d.r.) and 11 % overall yield. The synthesis also features a late-stage lithiation–borylation reaction with a tertiary amine containing carbenoid.
- Varela, Ana,Garve, Lennart K. B.,Leonori, Daniele,Aggarwal, Varinder K.
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supporting information
p. 2127 - 2131
(2017/02/15)
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- Catalytic Asymmetric Synthesis of Quaternary Barbituric Acids
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The catalytic asymmetric α-functionalization of prochiral barbituric acids, a subtype of pseudosymmetric 1,3-diamides, to yield the corresponding 5,5-disubstituted (quaternary) derivatives remains essentially unsolved. In this study 2-alkylthio-4,6-dioxopirimidines are designed as key 1,3-diamide surrogates that perform exceedingly in amine-squaramide catalyzed C-C bond forming reactions with vinyl ketones or Morita-Baylis-Hillmann-type allyl bromides as electrophiles. Mild acid hydrolysis of adducts affords barbituric acid derivatives with an in-ring quaternary carbon in unprecedented enantioselectivity, offering valuable materials for biological evaluations.
- Del Pozo, Sandra,Vera, Silvia,Oiarbide, Mikel,Palomo, Claudio
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supporting information
p. 15308 - 15311
(2017/11/06)
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- Stereocontrolled Synthesis of a Potential Transition-State Inhibitor of the Salicylate Synthase MbtI from Mycobacterium tuberculosis
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Mycobactins are small-molecule iron chelators (siderophores) produced by Mycobacterium tuberculosis (Mtb) for iron mobilization. The bifunctional salicylate synthase MbtI catalyzes the first step of mycobactin biosynthesis through the conversion of the primary metabolite chorismate into salicylic acid via isochorismate. We report the design, synthesis, and biochemical evaluation of an inhibitor based on the putative transition state (TS) for the isochorismatase partial reaction of MbtI. The inhibitor mimics the hypothesized charge buildup at C-4 of chorismate in the TS as well as C-O bond formation at C-6. Another important design element of the inhibitor is replacement of the labile pyruvate side chain in chorismate with a stable C-linked propionate isostere. We developed a stereocontrolled synthesis of the highly functionalized cyclohexene inhibitor that features an asymmetric aldol reaction using a titanium enolate, diastereoselective Grignard addition to a tert-butanesulfinyl aldimine, and ring closing olefin metathesis as key steps.
- Liu, Zheng,Liu, Feng,Aldrich, Courtney C.
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p. 6545 - 6552
(2015/10/06)
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- Enantioselective synthesis of xanthatin
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The enantioselective synthesis of cytostatic and antibiotic xanthatin (1 a) is reported. As a key intermediate, a bicyclic compound 2 was identified, which can be readily synthesized from methyl-2-furoic acid in diastereo- and enantiomerically pure form.
- Bergmann, Andreas,Reiser, Oliver
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supporting information
p. 7613 - 7615
(2014/07/07)
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- Baylis-Hillman reaction as a versatile platform for the synthesis of diverse functionalized polymers by chain and step polymerization
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The Baylis-Hillman reaction, which is a carbon-carbon bond forming reaction between an aldehyde and an activated alkene, was utilized to prepare densely functionalized monomers suitable for chain and step polymerization. By reacting formaldehyde with vari
- Peng, Chao,Joy, Abraham
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p. 1258 - 1268
(2014/03/21)
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- Development of asymmetric deacylative allylation
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Herein we present the development of asymmetric deacylative allylation of ketone enolates. The reaction directly couples readily available ketone pronucleophiles with allylic alcohols using facile retro-Claisen cleavage to form reactive intermediates in situ. The simplicity and robustness of the reaction conditions is demonstrated by the preparation of >6 g of an allylated tetralone from commercially available materials. Furthermore, use of nonracemic PHOX ligands allows intermolecular formation of quaternary stereocenters directly from allylic alcohols.
- Grenning, Alexander J.,Van Allen, Christie K.,Maji, Tapan,Lang, Simon B.,Tunge, Jon A.
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supporting information
p. 7281 - 7287
(2013/08/23)
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- Phosphine-catalyzed cascade [3 + 2] cyclization-allylic alkylation, [2 + 2 + 1] annulation, and [3 + 2] cyclization reactions between allylic carbonates and enones
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The phosphine-catalyzed annulations between Morita-Baylis-Hillman adduct carbonates and enones are reported. Under the catalysis of PBu3 (20 mol %), cascade [3 + 2] cyclization-allylic alkylation, [2 + 2 + 1] annulation, and [3 + 2] cyclization reactions chemoselectively occur depending on the substituent variation of both the carbonate and enone. These reactions provide efficient syntheses of highly functionalized cyclopentenes and cyclopentanes.
- Zhou, Rong,Wang, Jianfang,Song, Haibin,He, Zhengjie
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supporting information; scheme or table
p. 580 - 583
(2011/04/23)
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- Star-like PAA-g-PPO well-defined amphiphilic graft copolymer synthesized by ATNRC and SET-NRC reaction
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A series of well-defined amphiphilic star graft copolymers consisting of hydrophilic poly(acrylic acid) backbone and hydrophobic poly(propylene oxide) side chains were synthesized by the sequential reversible addition-fragmentation chain transfer (RAFT) p
- Li, Yaogong,Zhang, Yaqin,Yang, Dong,Hu, Jianhua,Lu, Guolin,Huang, Xiaoyu
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scheme or table
p. 2084 - 2097
(2011/03/22)
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- Convenient general asymmetric synthesis of roche ester derivatives through catalytic asymmetric hydrogenation: Steric and electronic effects of ligands
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An efficient and concise asymmetric hydrogenation of acrylate esters promoted by the cationic ruthenium monohydride complex [Ru(H) (hη6-cot)SYNPHOS]+BF44- is reported. A full investigation of the effects of catalyst precursors, solvents, temperature, hydrogen pressure, substrates as well as steric and electronic properties of ligands was carried out. The corresponding valuable Roche ester derivatives were obtained in good to excellent isolated yields and high enantioselectivities under mild conditions. The robustness and practicability of this highly enantioselective hydrogenation was demonstrated by the synthesis of the 3-hydroxy-2-methylpropanoic acid tert-butyl ester on a multigram scale, resulting in excellent yield and ee up to 94%.
- Pautigny, Cyrielle,Jeulin, Severine,Ayad, Tahar,Zhang, Zhaoguo,Genet, Jean-Pierre,Ratovelomanana-Vidal, Virginie
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supporting information; experimental part
p. 2525 - 2532
(2009/09/07)
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- Synthesis of chiral 2-hydroxy-1-methylpropanoates by rhodium-catalyzed stereoselective hydrogenation of α-(hydroxymethyl)-acrylate derivatives
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The synthesis of chiral 3-hydroxy-2-methylpropanoic acid esters (e.g., "Roche ester" 3a) based on the rhodium-catalyzed stereoselective hydrogenation of Baylis-Hillman reaction products was investigated. Full conversions and enantioselectivities of up to 99% at a substrate/catalyst ratio of up to 500/1 were achieved by application of bisphospholanes of the catASium M series as ancillary ligands. An interesting kinetic resolution was observed by the diastereoselective hydroxy-directed hydrogenation of related racemic β-branched precursors affording mainly anti-isomers with up to 96%ee.
- Holz, Jens,Schaeffner, Benjamin,Zayas, Odalys,Spannenberg, Anke,Boerner, Armin
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experimental part
p. 2533 - 2543
(2009/09/25)
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- An efficient synthesis of alkyl α-(hydroxymethyl)acrylates induced by DABCO in an aqueous medium
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Alkyl α-(hydroxymethyl)acrylates are prepared in high yields on a synthetic scale by hydroxymethylation of the corresponding acrylates using 30% aqueous formaldehyde in THF or DME as solvent and DABCO as the catalyst.
- Turki, Taoufik,Villiéras, Jean,Amri, Hassen
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p. 3071 - 3072
(2007/10/03)
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- The chemical development and scale-up of sampatrilat
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The discovery and scale-up of two routes to sampatrilat are described. The first Chemical R and D route used a side product from another development project to accelerate drug supply and expedite the early development programme. The second, more efficient Chemical R and D route had the potential for commercialisation and used an environmentally friendly variant of the Baylis-Hillman reaction, and an asymmetric Michael addition as key steps. Full preparative details for the aminomethacrylate 4, a potentially useful chiral synthon, are given for the first time, along with full experimental details of the asymmetric Michael addition to make the chiral glutarate 5. Finally, a striking polymorph case history is described.
- Dunn, Peter J.,Hughes, Michael L.,Searle, Patricia M.,Wood, Albert S.
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p. 244 - 253
(2013/09/06)
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- Rate acceleration of the Baylis-Hillman reaction in polar solvents (water and formamide). Dominant role of hydrogen bonding, not hydrophobic effects, is implicated
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A substantial acceleration of the Baylis-Hillman reaction between cyclohexenone and benzaldehyde has been observed when the reaction is conducted in water. Several different amine catalysts were tested, and as with reactions conducted in the absence of so
- Aggarwal, Varinder K.,Dean, David K.,Mereu, Andrea,Williams, Richard
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p. 510 - 514
(2007/10/03)
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- The aqueous trimethylamine mediated Baylis-Hillman reaction
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Aqueous trimethylamine mediated Baylis-Hillman coupling of alkyl acrylates with aldehydes is described.
- Basavaiah, Deevi,Krishnamacharyulu, Marimganti,Rao, Anumolu Jaganmohan
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p. 2061 - 2069
(2007/10/03)
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- Synthetic study on gymnodimine: Highly stereoselective construction of substituted tetrahydrofuran and cyclohexene moieties
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The synthetic studies on gymnodimine, a shellfish toxin, are described. This marine toxin consists of 16-membered carbocycle, tetrahydrofuran, and spiro-imine moieties. Our synthetic strategy involves the stereoselective allylation of tetrahydrofuran compound and the exo-selective intramolecular Diels-Alder reaction.
- Ishihara, Jun,Miyakawa, Jun,Tsujimoto, Takashi,Murai, Akio
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p. 1417 - 1419
(2007/10/03)
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