- A unique heterogeneous nucleophilic catalyst comprising methylated nitrogen-substituted porous silica provides high product selectivity for the Morita-Baylis-Hillman reaction
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Methylated nitrogen-substituted microporous and mesoporous silica exhibited almost the same catalytic performance as that of a conventional homogeneous base catalyst. They also demonstrated unexpectedly high product selectivity for the Morita-Baylis-Hillman reaction of formaldehyde with methyl acrylate at high temperatures.
- Furukawa, Yutaro,Ogura, Masaru
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Read Online
- New insights into the alkoxycarbonylation of propargyl alcohol
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The challenging carbonylation of propargyl alcohol is effectively catalyzed by Pd(OAc)2 in combination with diphenyl-(6-methyl-pyridin-2-yl)phosphine and methanesulfonic acid. In dichloroethane at 20–50 °C, the reaction affords with almost complete regioselectivity alkyl 2-(hydroxymethyl)acrylates. Turnover frequency numbers (TOF) of up to 450 h?1 can be achieved working at 50 °C, while a maximum turnover number (TON) of about 730 is obtained at 30 °C. The catalyst longevity is limited because the carbonylation product reacts with the phosphorus atom of the ligand to give a quaternary phosphonium salt. This reaction leads to deactivation of the catalyst and eventually to palladium black formation.
- Scrivanti,Beghetto,Bertoldini
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Read Online
- Synthesis of cynaropicrin-d4
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Cynaropicrin is a guaianolide sesquiterpene lactone, which has potent in vitro and in vivo inhibitory activity against Trypanosoma brucei, the protozoan parasite that causes human African trypanosomiasis (HAT; sleeping sickness). Herein, we describe the synthesis of cynaropicrin's deuterated derivative, cynaropicrin-d4, by the replacement of the side chain of natural cynaropicrin. The synthesized cynaropicrin-d4 could be employed as an internal standard for liquid chromatography-mass spectrometry (LC-MS) analysis, in the pharmacokinetic study of cynaropicrin. This could potentially advance the study of this therapeutic lead.
- Sato, Takuya,Hara, Shihori,Sato, Makiko,Ogawa, Keita,Adams, Michael,Usuki, Toyonobu
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Read Online
- Stereoselective synthesis of the (?)-dysiherbaine furopyran core via BF3-promoted formal [3+2] annulation of aldehydo-aldoses with allylsilanes
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A highly stereoselective synthesis of the hexahydrofuro[3,2-b]pyran core of (?)-dysiherbaine is described. The key step in this synthesis includes the stereocontrolled formation of the tetrahydrofuran ring using the formal [3+2] annulation of the isopropylidene-protected aldehydo-L-arabinose and the β-substituted allylsilane mediated by trifluoroborane etherate.
- Hotoda, Koki,Ohnuma, Asami,Kusakabe, Kosuke,Tanaka, Aki,Sasaki, Ikuo,Sugimura, Hideyuki
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Read Online
- 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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- Reaction type ultraviolet light absorber and preparation method and application thereof
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The invention discloses a reaction type ultraviolet light absorber as well as a preparation method and application thereof. The method is characterized by comprising the following steps; with paraformaldehyde as an initial raw material, synthesizing 2-(bromomethyl) methyl acrylate; then carrying out a reaction on the 2-(bromomethyl) methyl acrylate and 2,2',4,4'-dichlorophenol as a reactant by controlling the temperature, and the types of the solvents and alkalis to obtain the reaction type ultraviolet light absorber. The reaction type ultraviolet light absorber contains unsaturated carbon-carbon double bonds, wherein the main ultraviolet light absorption range is 250-400 nm; the reaction type ultraviolet light absorber is a novel broad-spectrum ultraviolet light absorber, the synthesis process is convenient to operate, the raw materials are low in price and easy to obtain, and the reaction type ultraviolet light absorber has very high market value and application value.
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Paragraph 0047-0049
(2020/07/03)
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- HYDROXYL GROUP-CONTAINING VINYL COMPOUND PRODUCTION PROCESS
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PROBLEM TO BE SOLVED: To provide a hydroxyl group-containing vinyl compound production process in which a hydroxyl group-containing vinyl compound, in which the content of ether dimer of hydroxyl group-containing vinyl compound having high skin irritancy is sufficiently suppressed, can be produced at a lower cost than before. SOLUTION: Provided is a hydroxyl group-containing vinyl compound production process. The production process comprises a step of reacting an acrylic acid ester and an aldehyde compound in the presence of a tertiary amine compound, and a step of removing the acrylic acid ester from the reaction liquid after the reaction step, and is characterized in that the content of the ether dimer of the hydroxyl group-containing vinyl compound in the reaction liquid after the acrylic acid ester removing step is 9.0 mass% or less with respect to 100 mass% of the hydroxyl group-containing vinyl compound. SELECTED DRAWING: None COPYRIGHT: (C)2020,JPOandINPIT
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Paragraph 0051-0055
(2020/06/30)
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- Photoredox Decarboxylative Alkylation/(2+2+1) Cycloaddition of 1,7-Enynes: A Cascade Approach Towards Polycyclic Heterocycles Using N-(Acyloxy)phthalimides as Radical Source
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No Abstract. (Figure presented.).
- Correia, José Tiago Menezes,Piva da Silva, Gustavo,André, Elias,Paix?o, Márcio Weber
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supporting information
p. 5558 - 5564
(2019/09/16)
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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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- Electrochemistry-Enabled Ir-Catalyzed Vinylic C-H Functionalization
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Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C-H functionalization, yet this type of transformation has thus far mainly been limited to arene C-H functionalization. Herein, we report the development of electrochemical vinylic C-H functionalization of acrylic acids with alkynes. In this reaction an iridium catalyst enables C-H/O-H functionalization for alkyne annulation, affording α-pyrones with good to excellent yields in an undivided cell. Preliminary mechanistic studies show that anodic oxidation is crucial for releasing the product and regeneration of an Ir(III) intermediate from a diene-Ir(I) complex, which is a coordinatively saturated, 18-electron complex. Importantly, common chemical oxidants such as Ag(I) or Cu(II) did not give significant amounts of the desired product in the absence of electrical current under otherwise identical conditions.
- Yang, Qi-Liang,Xing, Yi-Kang,Wang, Xiang-Yang,Ma, Hong-Xing,Weng, Xin-Jun,Yang, Xiang,Guo, Hai-Ming,Mei, Tian-Sheng
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supporting information
p. 18970 - 18976
(2019/12/04)
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- Macrolide Synthesis through Intramolecular Oxidative Cross-Coupling of Alkenes
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A RhIII-catalyzed intramolecular oxidative cross-coupling between double bonds for the synthesis of macrolides is described. Under the optimized reaction conditions, macrocycles containing a diene moiety can be formed in reasonable yields and with excellent chemo- and stereoselectivity. This method provides an efficient approach to synthesize macrocyclic compounds containing a 1,3-conjugated diene structure.
- Jiang, Bing,Zhao, Meng,Li, Shu-Sen,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 555 - 559
(2018/02/21)
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- Preparation method of 5,5-dimethyl-3-methylene pyrrolidine-2-ketone
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The invention discloses a preparation method of 5,5-dimethyl-3-methylene pyrrolidine-2-ketone. The preparation method comprises the following steps: (S1) under the action of strong organic alkali, formaldehyde and a compound I generate condensation reaction to obtain a compound II; (S2) the compound II and a halogenating reagent generate halogenating reaction to obtain a compound III; (S3) under the action of the strong organic alkali, the compound III and 2-nitropropane generate substitution reaction to obtain a nitryl-containing compound IV; (S4) the compound IV carries out domino reaction of reducing nitryl and closing rings under the action of a catalyst and a reducing agent to obtain the 5,5-dimethyl-3-methylene pyrrolidine-2-ketone. The preparation method disclosed by the invention has the beneficial effects that the synthetic steps are fewer, the implementation is simple and easy, no harsh reaction condition is needed, the process route is novel, the yield is more than 50%, andthe reaction heat and gas generation is well controlled. The preparation method disclosed by the invention has the characteristics of novel process route, relatively mild reaction conditions, easy expansion, large-scale production and the like.
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Paragraph 0017
(2018/04/28)
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- Modular 1,1′-Ferrocenediyl-cored P-Stereogenic Diphosphines: ′′JDayPhos′′ Series and its Use in Rhodium(I)-Catalyzed Hydrogenation
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A novel ferrocene-based P-stereogenic diphospine ligand series dubbed JDayPhos was developed, which rhodium(I) complexes of some of its members exhibited excellent enantioselectivity (up to >99% ee) and high activity in asymmetric hydrogenation of β-unsubstituted or -substituted itaconates and α-methylene-γ-oxo-carboxylates. (Figure presented.).
- Poklukar, Ga?per,Stephan, Michel,Mohar, Barbara
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supporting information
p. 2566 - 2570
(2018/05/16)
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- Umpolung of o-Hydroxyaryl Azomethine Ylides: Entry to Functionalized ?-Aminobutyric Acid under Phosphine Catalysis
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A phosphine-catalyzed reaction between o-hydroxyaryl azomethine ylides and MBH carbonates provides access to highly functionalized ?-aminobutyric acid derivatives in moderate to good yields. Mechanistically, the reaction involves a phosphine-catalyzed tandem SN2′/2-aza-Cope rearrangement/intramolecular addition process.
- Chen, Qingqing,Bao, Yishu,Yang, Xiuqin,Dai, Zonghao,Yang, Fulai,Zhou, Qingfa
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supporting information
p. 5380 - 5383
(2018/09/13)
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- Amplified synthetic process of 2-hydroxymethyl methyl acrylate and analogue
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The invention relates to an amplified synthetic process of 2-hydroxymethyl methyl acrylate and an analogue. The amplified synthetic process is characterized in that a Baylis-Hillman reaction route is utilized, cheap methyl acrylate is simultaneously taken as a reactant and a reaction solvent, and meanwhile, organic alkali or inorganic alkali is added to be matched with DABCO catalysis reaction so as to obtain the product. Excess cheap methyl acrylate is simultaneously taken as the reactant and the reaction solvent, so that the byproduct of dual hydroxymethylation is inhibited, meanwhile, the cost is lowered, and the reaction can be further accelerated. Excess methyl acrylate can be recycled and reused, so that the numbers of byproducts and three wastes are reduced. Meanwhile, the process is completely suitable for producing 2-hydroxymethyl methyl acrylate and other ester type compounds.
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Paragraph 0028; 0029; 0030; 0031
(2017/12/28)
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- HYDROXYL GROUP-CONTAINING VINYL COMPOUND PRODUCTION PROCESS
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PROBLEM TO BE SOLVED: To provide a hydroxyl group-containing vinyl compound production process in which a hydroxyl group-containing vinyl compound, in which the content of ether dimer of hydroxyl group-containing vinyl compound having high skin irritancy is sufficiently suppressed, can be produced at a lower cost than before. SOLUTION: Provided is a hydroxyl group-containing vinyl compound production process. The production process comprises a step of reacting an acrylic acid ester and an aldehyde compound in the presence of a tertiary amine compound, and a step of removing the acrylic acid ester from the reaction liquid after the reaction step, and is characterized in that the content of the ether dimer of the hydroxyl group-containing vinyl compound in the reaction liquid after the acrylic acid ester removing step is 9.0 mass% or less with respect to 100 mass% of the hydroxyl group-containing vinyl compound. SELECTED DRAWING: None COPYRIGHT: (C)2017,JPOandINPIT
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Paragraph 0051
(2017/06/24)
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- Preparation method of 2-hydroxymethyl methyl acrylate
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The invention discloses a preparation method of 2-hydroxymethyl methyl acrylate. The method includes the steps of firstly, mixing triphenyl phosphine, a catalyst and solvent, and dropwise adding 2-methyl bromoacetate to mixed liquid for temperature raising reaction; secondly, after reaction ends, being standing still and separating phases to separate out a methylbenzene phase; thirdly, dropwise adding a sodium hydroxide aqueous solution for cooling and crystallizing; fourthly, conducting suction filtration, and rinsing a filter cake with n-heptane to prepare methoxycarbonyl methylene triphenyl phosphoric chloride, namely a Wittig reagent; fifthly, adding the Wittig reagent to water, adding a formaldehyde aqueous solution, and dropwise adding a potassium carbonate aqueous solution for reaction; sixthly, filtering out triphenyl phosphine; seventhly, adding the solvent to filtrate for extraction; eighthly, concentrating an organic phase, and conducting reduced pressure distillation after removing the solvent to obtain 2-hydroxymethyl methyl acrylate. The raw materials are easy to obtain, production cost is low, and the method is suitable for industrial production and high in product yield.
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Paragraph 0031; 0034; 0035
(2017/06/02)
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- Synthesis of Substituted Quinolizidines via a Gold-Catalyzed Double Cyclization Cascade
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A novel synthesis of quinolizidines by a cationic gold-catalyzed double cyclization cascade has been developed. The reaction was initiated by the gold-catalyzed 6-exo-dig cyclization of ynamides, which was followed by a second cyclization of an enamide intermediate to provide the corresponding quinolizidine derivatives. The utility of this reaction was demonstrated by application to the synthesis of multi-substituted quinolizidines and by the total synthesis of a quinolizidine alkaloid, (±)-lupinine.
- Nonaka, Shiori,Sugimoto, Kenji,Ueda, Hirofumi,Tokuyama, Hidetoshi
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supporting information
p. 380 - 385
(2016/02/12)
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- Anomalous Reactivity and Selectivity in the Intermolecular Diels-Alder Reactions of Multisubstituted Acyclic Dienes with Geometrical Isomers of Enals
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A Lewis-acid catalyzed intermolecular Diels-Alder reaction between multisubstituted acyclic dienes and the E and Z isomers of α,β-enals was studied. It was found that the diene reacted selectively with the Z-isomer of the α,β-enal.
- Zhou, Jia-Hui,Cai, Sai-Hu,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 2355 - 2358
(2016/06/09)
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- Radical Isomerization and Cycloisomerization Initiated by H? Transfer
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Under H2 pressure, CoII(dmgBF2)2L2 (L = H2O, THF) generates a low concentration of an H? donor. Transfer of the H? onto an olefin gives a radical that can either (1) transfer an H? back to the metal, generating an isomerized olefin, or (2) add intramolecularly to a double bond, generating a cyclized radical. Transfer of an H? back to the metal from the cyclized radical results in a cycloisomerization. Both outcomes are favored by the low concentration of the cobalt H? donor, whereas hydrogenation and cyclohydrogenation are more likely with other catalysts (when the concentration of the H? donor is high).
- Li, Gang,Kuo, Jonathan L.,Han, Arthur,Abuyuan, Janine M.,Young, Lily C.,Norton, Jack R.,Palmer, Joshua H.
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supporting information
p. 7698 - 7704
(2016/07/06)
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- Highly functionalized donor-acceptor cyclopropanes applied toward the synthesis of the Melodinus alkaloids
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Abstract A series of highly substituted vinylcyclopropanes were prepared and examined as reaction partners in a palladium-catalyzed (3+2) cycloaddition with nitrostyrenes. Described herein are our efforts to synthesize an elusive 1,1-divinylcyclopropane by several distinct approaches, and to apply surrogates of this fragment toward the synthesis of the Melodinus alkaloids.
- Goldberg, Alexander F.G.,Craig, Robert A.,O'Connor, Nicholas R.,Stoltz, Brian M.
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supporting information
p. 2983 - 2990
(2015/05/27)
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- Enantioselective synthesis of putative lipiarmycin aglycon related to fidaxomicin/tiacumicin B
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An enantioselective synthesis of a putative lipiarmycin aglycon was accomplished and features: 1) Brown's enantioselective alkoxyallylboration and allylation of aldehydes, 2) chain elongation by iterative Horner-Wadsworth-Emmons olefination, 3) Evans' aldol reaction and 4) an enediene ring-closing metathesis. A neighboring-group-assisted chemoselective reductive desilylation was uncovered in this study and was instrumental to the realization of the present synthesis.
- Erb, William,Grassot, Jean-Marie,Linder, David,Neuville, Luc,Zhu, Jieping
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supporting information
p. 1929 - 1932
(2015/02/19)
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- Synthesis of the major metabolites of febuxostat
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Total synthesis of three Febuxostat metabolites, named 67M-1, 67M-2, and 67M-4,is described in this article. Through condensation of the key intermediate compound A with different side chains, and then oxidation and hydrolysis, we obtained three target compounds with an overall yield of 19.5%-28.0%.
- Li, Xiao Long,Qiu, Rui,Wan, Wei Li,Cheng, Xu,Hai, Li,Wu, Yong
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p. 217 - 221
(2015/06/23)
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- Finding the Selectivity Switch - A Rational Approach towards Stereocomplementary Variants of the Ene Reductase YqjM
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Ene reductases from the Old Yellow Enzyme family are versatile biocatalysts useful for the synthesis of optically active compounds. One disadvantage of biocatalysts when compared to competing catalysts in chemical syntheses is that often only one stereoisomer of the product is available. Another drawback can be the lack of activity in certain enzyme-substrate combinations. We were able to approach both of these challenges rationally in the case of the enzymatic synthesis of methyl 3-hydroxy-2-methylpropanoate (commonly denoted as the Roche ester) and derivatives thereof using the ene reductase YqjM. By a highly efficient, concept-based approach of designing mutant variants of YqjM and engineering substrates we could alter both the rate constant and the enantioselectivity of the reaction. Preparative scale reactions have been performed with successful mutants. In addition, the iterative modification of the substrate gave experiment-based insights into the binding mode of the Roche ester precursor and its derivatives.
- Rüthlein, Elisabeth,Classen, Thomas,Dobnikar, Lina,Sch?lzel, Melanie,Pietruszka, J?rg
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supporting information
p. 1775 - 1786
(2015/06/02)
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- B(C6F5)3: A New Class of Strong and Bulky Lewis Acid for Exo-Selective Intermolecular Diels-Alder Reactions of Unreactive Acyclic Dienes with α,β-Enals
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Lewis acid B(C6F5)3 catalyzed the Diels-Alder reactions of multisubstituted open-chain dienes and α,β-enals to afford the desired products with high exo-selectivities are reported. The substituent effect of the dienes and dienophiles on the products stereoselectivity was thoroughly investigated, and it was found that most of the desired exo-Diels-Alder products could be obtained in good yields and with high exo-stereoselectivities.
- Zhou, Jia-Hui,Jiang, Bing,Meng, Fei-Fan,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 4432 - 4435
(2015/09/28)
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- Synthesis, in vitro, and in vivo evaluation of novel functionalized quaternary ammonium curcuminoids as potential anti-cancer agents
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Novel functionalized quaternary ammonium curcuminoids have been synthesized from piperazinyl curcuminoids and Baylis-Hillman reaction derived allyl bromides. These molecules are found to be highly water soluble with increased cytotoxicity compared to native curcumin against three cancer cell lines MIAPaCa-2, MDA-MB-231, and 4T1. Preliminary in vivo toxicity evaluation of a representative curcuminoid 5a in healthy mice indicates that this molecule is well tolerated based on normal body weight gains compared to control group. Furthermore, the efficacy of 5a has been tested in a pancreatic cancer xenograft model of MIAPaCa-2 and has been found to exhibit good tumor growth inhibition as a single agent and also in combination with clinical pancreatic cancer drug gemcitabine.
- Solano, Lucas N.,Nelson, Grady L.,Ronayne, Conor T.,Lueth, Erica A.,Foxley, Melissa A.,Jonnalagadda, Sravan K.,Gurrapu, Shirisha,Mereddy, Venkatram R.
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p. 5777 - 5780
(2015/11/24)
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- 4-(Dimethylamino)pyridine as a catalyst for the lactonization of 4-hydroxy-2-methylenebutanoate esters
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The catalytic action of 4-(dimethylamino)pyridine (DMAP) in lactonizing 4-hydroxy-2-methylenebutanoate esters to 2-methylene-γ-butyrolactones is described. The use of DMAP, which functions as an excellent complement to the more traditional acid-catalyzed lactonization protocol, allows for the synthesis of 2-methylene-γ-butyrolactones containing acid-sensitive groups under essentially neutral conditions.
- Nicponski, Daniel R.
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supporting information
p. 2075 - 2077
(2014/04/03)
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- Diastereoselective synthesis of α-(aminomethyl)-γ-butyrolactones via a catalyst-free aminolactonization
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An auto-catalytic domino reaction, presumably involving an aza-Michael reaction, proton transfer, and lactonization, furnishing α-(aminomethyl)-γ-butyrolactones in near quantitative yields and excellent diastereoselectivity is described.
- Ramachandran, P. Veeraraghavan,Nicponski, Daniel R.
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supporting information
p. 15216 - 15219
(2015/01/08)
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- Synthesis of enantiopure β2-homoalanine derivatives via rhodium catalyzed asymmetric hydrogenation
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The stereoselective synthesis of chiral β2-homoalanine derivatives with 99% ee by the Rh-catalyzed enantioselective hydrogenation of prochiral 2-aminomethyl acrylates is described. The subsequent transformation to chiral 3-amino-2-methylpropanols is also demonstrated.
- Luehr, Susan,Holz, Jens,Zayas, Odalys,Seidelmann, Oliver,Domke, Lutz,Boerner, Armin
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p. 395 - 401
(2013/06/27)
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- Synthesis and biological evaluation of novel benzoxaboroles as potential antimicrobial and anticancer agents
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Several novel benzoxaborole derivatives were synthesized starting from 2-formylphenylboronic acid utilizing Baylis-Hillman reaction, Barbier allylation, Passerini reaction, and aldol reaction protocols as the key step. All the synthesized benzoxaboroles have been evaluated for their antibacterial, antifungal, and anticancer activities.
- Sravan Kumar,Alam,Gurrapu, Shirisha,Nelson, Grady,Williams, Michael,Corsello, Michael A.,Johnson, Joseph L.,Jonnalagadda, Subash C.,Mereddy, Venkatram R.
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p. 814 - 820
(2013/08/23)
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- Ruthenium- and rhodium-catalyzed cross-coupling reaction of acrylamides with alkenes: Efficient access to (Z,E)-dienamides
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Ruthenium- and rhodium-catalyzed direct oxidative cross-coupling reactions of acrylamides with alkenes were developed. These methods provide an efficient route for the synthesis of (Z,E)-dienamides in excellent yields with good stereoselectivity. The catalytic systems allowed oxidative olefination of a wide range of alkenes bearing different functional groups, such as CO2R, COMe, SO2Ph, aryl, CONHBn, CN, PO(OEt)2, as well as Weinreb amide.
- Zhang, Jian,Loh, Teck-Peng
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supporting information
p. 11232 - 11234
(2013/01/15)
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- BICYCLIC ARYL SPHINGOSINE 1-PHOSPHATE ANALOGS
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Compounds that have agonist activity at one or more of the SlP receptors are provided. The compounds are sphingosine analogs that, after phosphorylation, can behave as agonists at SlP receptors.
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Page/Page column 72
(2011/02/24)
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- Regioselective radical bromoallylation of allenes leading to 2-bromo-substituted 1,5-dienes
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The regioselective radical bromoallylation of allenes proceeded efficiently in the presence of AIBN as a radical initiator to give 2-bromo-substituted 1,5-dienes in excellent yields. The addition of a bromine radical took place regioselectively onto the central carbon of allenes generating a stable allyl radical, which underwent addition/β-fragmentation reactions with allylbromides. The products could be further functionalized by Pd-catalyzed coupling reactions.
- Kippo, Takashi,Fukuyama, Takahide,Ryu, Ilhyong
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supporting information; experimental part
p. 3864 - 3867
(2011/09/15)
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- Novel methodologies for the synthesis of functionalized pyroglutamates
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Alkylation of amino-acid derived iminoesters with Baylis-Hillman (BH) template based allyl bromides furnished α-methylene-β-substituted- pyroglutamates, while the corresponding alkylation with BH derived allylic acetates provided α-alkylidene-pyroglutamates. These methodologies have been applied in the synthesis of fused [3.2.0]-γ-lactam-β-lactones.
- Tekkam, Srinivas,Alam,Jonnalagadda, Subash C.,Mereddy, Venkatram R.
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body text
p. 3219 - 3221
(2011/05/05)
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- A general approach to the synthesis of β2-amino acid derivatives via highly efficient catalytic asymmetric hydrogenation of α-aminomethylacrylates
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A new strategy was developed for the synthesis of a valuable class of α-aminomethylacrylates via the Baylis-Hillman reaction of different aldehydes with methyl acrylate followed by acetylation of the resulting allylic alcohols and SN2′-type amination of the allylic acetates. Asymmetric hydrogenation of these diverse olefinic precursors using rhodium(Et-Duphos) catalysts provided the corresponding β2-amino acid derivatives with excellent enantioselectivities and exceedingly high reactivities (up to >99.5% ee and S/C=10,000). The first hydrogenation of (Z)-configurated substrates was studied for the synthesis of β2-amino acid derivatives. The high influence of the substrate geometry and steric hindrance on the reactivity and enantioselectivity was also disclosed for this reaction. This protocol provides a highly practical, facile and scalable method for the preparation of optically pure β2- amino acids and their derivatives under mild reaction conditions.
- Guo, Yujuan,Shao, Guang,Li, Lanning,Wu, Wenhao,Li, Ruihong,Li, Jingjing,Song, Jian,Qiu, Liqin,Prashad, Mahavir,Kwong, Fuk Yee
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experimental part
p. 1539 - 1553
(2010/08/22)
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- Structure-activity relationships of tulipalines, tuliposides, and related compounds as inhibitors of MurA
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The enzyme MurA performs an essential step in peptidoglycan biosynthesis and is therefore a target for the discovery of novel antibacterial compounds. We report here the inhibition of MurA by natural products from tulips (tulipalines and tuliposides), and the structure-activity relationships of various derivatives. The inhibition of MurA can be related to antibacterial activity, and MurA is probably one of the relevant molecular targets of the tulipaline derivatives. MurA inhibition by this class of compounds depends on the presence of the substrate UNAG, which indicates non-covalent suicide inhibition as observed previously for cnicin. With respect to selectivity, however, the reactivity against arbitrary sulfhydryl groups, such as in glutathione, could not yet be sufficiently separated from MurA inhibition in the present dataset.
- Mendgen, Thomas,Scholz, Therese,Klein, Christian D.
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supporting information; experimental part
p. 5757 - 5762
(2010/12/24)
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- 1-Aminoxymethylcyclopropanecarboxylic acid as building block of β N-O turn and helix: Synthesis and conformational analysis in solution and in the solid state
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Cyclopropane side-chained β2,2-aminoxy oligopeptides were synthesized and conformationally studied. β N-O turn in solution and β N-O helix in the solid state was characterized by 1H NMR, 2D NOESY and FT-IR as well as X-ray crystallography studies. Almost no changes has been observed with the disturbance at α carbon bond angle compared with dimethyl substituted one. This study provided the opportunity to design the bioactive peptidomimetics in a more elaborate way.
- Chang, Xiao-Wei,Han, Qing-Chuan,Jiao, Zhi-Gang,Weng, Lin-Hong,Zhang, Dan-Wei
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supporting information; experimental part
p. 9733 - 9737
(2011/02/25)
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- Asymmetric synthesis of (R)-3-hydroxy-2-methylpropanoate ('Roche Ester') and derivatives via biocatalytic C=C-bond reduction
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Enoate reductases from the 'old yellow enzyme' family were employed for the asymmetric bioreduction of methyl 2-hydroxymethylacrylate and its O-allyl, O-benzyl and O-TBDMS derivatives to furnish (R)-configurated methyl 3-hydroxy-2-methylpropionate products in up to >99% ee Variation of the O-protective group had little influence on the stereoselectivity, but a major impact on the reaction rate.
- Stueckler, Clemens,Winkler, Christoph K.,Bonnekessel, Melanie,Faber, Kurt
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supporting information; experimental part
p. 2663 - 2666
(2010/12/25)
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- Development of practical methodologies for the synthesis of functionalized benzoboroxoles
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2-Formylphenylboronic acids upon reaction with activated olefins such as acrylates, methyl vinyl ketone, and acrylonitrile provide functionalized benzoboroxoles. The corresponding homologated benzoboroxoles were synthesized via the reaction of 2-formylphenylboronic acids with α- bromomethylacrylates.
- Kumar, J. Sravan,Bashian, Christopher M.,Corsello, Michael A.,Jonnalagadda, Subash C.,Mereddy, Venkatram R.
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scheme or table
p. 4482 - 4485
(2010/10/01)
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- Facile 1,3-diaza-Claisen rearrangements of tertiary allylic amines bearing an electron-deficient alkene
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(Chemical Equation Presented) Tertiary allylic amines with an electron-deficient alkene react with isocyanates and isothiocyanates to give highly substituted ureas and thioureas arising from formal 1,3-diaza-Claisen rearrangements. Isocyanates and isothiocyanates with strong electron-withdrawing groups are more reactive. Similarly, the data suggest that a stronger electron-withdrawing substituent on the alkene favors a faster reaction, but this may be offset by sterlcs in the cyclic transition state.
- Aranha, Rachel M.,Bowser, Amy M.,Madalengoitia, Jose S.
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supporting information; experimental part
p. 575 - 578
(2009/07/18)
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- A concise total synthesis of saliniketal B
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(Chemical Equation Presented) We report a concise, enantioselective, and highly efficient synthesis of the marine actinomycete-derived natural product saliniketal B. Our approach was motivated with an eye toward future structure-function studies of this inhibitor of phorbol ester-mediated ornithine decarboxylase induction via an unknown mechanism. Our strategy highlights the utility of Pt (II)-mediated cycloisomerization of alkynediols developed in our laboratory to construct the dioxabicyclo[3.2.1]octane ring system, a highly selective aldol fragment coupling whose stereochemical outcome is influenced by a γ-stereogenic methyl group, and an interesting one-pot desilylation/dihydropyranone fragmentation/amidation sequence. As such, saliniketal B was obtained in 11 steps and 23% overall yield from commercially available starting material via a convergent coupling of two equally complex fragments assembled in seven and eight steps (39 and 45%), respectively.
- Liu, Jun,De Brabander, Jef K.
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supporting information; experimental part
p. 12562 - 12563
(2010/01/30)
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- Synthesis of β2-homophenylalanine derivatives by Negishi cross-coupling reactions
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Three approaches to the synthesis of β2-homophenylalanine derivatives using Negishi cross-coupling reaction are reported. In the first two approaches, two protected α-iodomethyl-β-amino esters are each converted into the corresponding organozinc iodides, which then undergo Pd-catalysed cross-coupling with aromatic halides to give β2-homophenylalanine derivatives, and the X-ray crystal structure of one product is reported. Alternatively, Negishi cross-coupling of the zinc reagent derived from N-benzyl 3-iodomethyl azetidin-2-one and aryl halides gave 3-benzylazetidin-2-ones, masked β2-homophenylalanine derivatives. The X-ray crystal structure of 1-benzyl-3-[(p-toluenesulfonyloxy)-methyl]-azetidin-2-one confirms the structural assignment.
- Bartrum, Hannah E.,Adams, Harry,Caggiano, Lorenzo,Jackson, Richard F.W.
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p. 3701 - 3712
(2008/09/20)
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- Acyloins from Morita-Baylis-Hillman adducts: an alternative approach to the racemic total synthesis of bupropion
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In this Letter, we describe an easy and straightforward strategy for the preparation of acyloins (α-hydroxyketones) from Morita-Baylis-Hillman adducts, based on a Curtius rearrangement. Different acyloins were obtained with good overall yield (>40% for three steps). To exemplify the synthetic usefulness of this strategy, total synthesis of (±)-bupropion, a dopamine, and nor-epinefrine reuptake inhibitor has been accomplished in eight steps with an overall yield of 25%.
- Amarante, Giovanni W.,Rezende, Patrícia,Cavallaro, Mayra,Coelho, Fernando
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p. 3744 - 3748
(2008/09/21)
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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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- 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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- Total syntheses of natural tubelactomicins B, D, and E: Establishment of their stereochemistries
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(Chemical Equation Presented) Total syntheses of the antimicrobial tricyclic 16-membered macrolides, (+)-tubelactomicin B, (+)-tubelactomicin D, and (+)-tubelactomicin E, have been accomplished for the first time with common synthetic approaches. These total syntheses established the relative and absolute configurations of the three tubelactomicins, for which planar structures had solely been reported. The total synthesis of (+)-tubelactomicin D included a newly developed stereoselective intramolecular Diels-Alder reaction for constructing the highly functionalized octahydronaphthalene substructures.
- Sawamura, Kiyoto,Yoshida, Keigo,Suzuki, Akari,Motozaki, Toru,Kozawa, Ikuko,Hayamizu, Takashi,Munakata, Ryosuke,Takao, Ken-Ichi,Tadano, Kin-Ichi
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p. 6143 - 6148
(2008/02/10)
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