- Understanding the Structure–Polymerization Thermodynamics Relationships of Fused-Ring Cyclooctenes for Developing Chemically Recyclable Polymers
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Polymers that can be chemically recycled to their constituent monomers offer a promising solution to address the challenges in plastics sustainability through a circular use of materials. The design and development of monomers for next-generation chemical
- Sathe, Devavrat,Wang, Junpeng,Zhou, Junfeng
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supporting information
p. 928 - 934
(2022/01/19)
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- Epimerization of Tertiary Carbon Centers via Reversible Radical Cleavage of Unactivated C(sp3)-H Bonds
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Reversible cleavage of C(sp3)-H bonds can enable racemization or epimerization, offering a valuable tool to edit the stereochemistry of organic compounds. While epimerization reactions operating via cleavage of acidic C(sp3)-H bonds, such as the Cα-H of carbonyl compounds, have been widely used in organic synthesis and enzyme-catalyzed biosynthesis, epimerization of tertiary carbons bearing a nonacidic C(sp3)-H bond is much more challenging with few practical methods available. Herein, we report the first synthetically useful protocol for the epimerization of tertiary carbons via reversible radical cleavage of unactivated C(sp3)-H bonds with hypervalent iodine reagent benziodoxole azide and H2O under mild conditions. These reactions exhibit excellent reactivity and selectivity for unactivated 3° C-H bonds of various cycloalkanes and offer a powerful strategy for editing the stereochemical configurations of carbon scaffolds intractable to conventional methods. Mechanistic study suggests that the unique ability of N3? to serve as a catalytic H atom shuttle is critical to reversibly break and reform 3° C-H bonds with high efficiency and selectivity.
- Wang, Yaxin,Hu, Xiafei,Morales-Rivera, Cristian A.,Li, Guo-Xing,Huang, Xin,He, Gang,Liu, Peng,Chen, Gong
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supporting information
p. 9678 - 9684
(2018/07/21)
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- Total synthesis of (+)-brefeldin C, (+)-nor-Me brefeldin A and (+)-4-epi-nor-Me brefeldin A
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A total synthesis of (+)-brefeldin C (BFC) and two brefeldin A (BFA) analogues - (+)-nor-Me BFA and (+)-4-epi-nor-Me BFA - has been developed. Key features of the syntheses include desymmetrization of meso anhydrides, a Carreira reaction to control the ab
- Archambaud, Sylvie,Legrand, Frederic,Aphecetche-Julienne, Karine,Collet, Sylvain,Guingant, Andre,Evain
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scheme or table
p. 1364 - 1380
(2010/05/03)
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- Oxidative carbomethoxylation of alkenes using a Pd(II)/molybdovanadophosphate (NPMoV) system under carbon monoxide and air
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Oxidative carbomethoxylation of cyclopentene (1) under carbon monoxide and air by the use of a catalytic amount of Pd(OAc)2 and molybdovanadophosphate (NPMoV) led to dimethyl cis-1,2-cyclopentanedicarboxylate (2) and dimethyl cis-1,3-cyclopentanedicarboxylate (3) in good yields. Total yields of 2 and 3 were found to be improved by adding a small amount of NH4Cl. Several alkenes were similarly converted into the corresponding dimethyl dicarboxylates. The role of Cl- in the present catalytic system is suggested.
- Yokota, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 5005 - 5008
(2007/10/03)
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- Synthesis and First Applications of a New Chiral Auxiliary (tert-Butyl 2-(tert-Butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate)
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Both enantiomers of tert-butyl 2(tert-butyl)-5,5-dimethyl-4-oxoimidazolidine-1-carboxylate (11; Bbdmoic) were prepared from L-alanine (Schemes 1 and 2).The parent heterocycle, 2-tert-butyl-5,5-dimethylimidazolidin-4-one (12; from 2-aminoisobutyramide, H-A
- Studer, Armido,Hintermann, Tobias,Seebach, Dieter
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p. 1185 - 1206
(2007/10/02)
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- Synthesis of Dimethyl 1,2-Cycloalkanedicarboxylates by Electrochemical Cyclization of Dimethyl α,α-Dibromoalkanedioates Using a Copper Anode
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The electrochemical cyclization of dimethyl α,α'-dibromoalkanedioates by making use of a platinum cathode and a copper anode in the presence of sodium iodide gave three- to six-membered dimethyl 1,2-cycloalkanedicarboxylates in good yields.
- Tokuda, Masao,Hayashi, Atsushi,Suginome, Hiroshi
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p. 2590 - 2592
(2007/10/02)
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- Electrochemical Coupling of Activated Olefins and Alkyl Dihalides: Formation of Cyclic Compounds
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The electrochemical coupling of dimethyl maleate, methyl cinnamate, 4-phenyl-3-buten-2-one, or methyl acrylate with dibromomethane, 1,3-dibromopropane, 1,4-dibromobutane or other substituted alkyl dihalogenides gave satisfactory yields of cyclic products.The reactions were performed in an undivided cell fitted with a sacrificial aluminum anode, in N-methylpyrrolidone (NMP), at constant current, and at room temperature.The role of the anodically generated metallic ions in this cyclocondensation has been evidenced.
- Lu, Yu-Wei,Nedelec, Jean-Yves,Folest, Jean-Claude,Perichon, Jacques
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p. 2503 - 2507
(2007/10/02)
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- A CYCLOPENTANE, CYCLOPENTENE AND CYCLOPENTANONE ANNULATION METHODOLOGY
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The chemistry derived from the dienolates of 1,2-dicarboxylic acid esters is described.New methods for preparing cyclopentane, cyclopentene and cyclopentanone rings affixed to the diesters are discussed.
- Wilkening, David,Mundy, Bradford P.
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p. 227 - 238
(2007/10/02)
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- A Study of Stereoselective Hydrolysis of Symmetrical Diesters with Pig Liver Esterase
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Pig liver esterase (PLE) catalyzed hydrolysis of dimethyl esters of symmetrical dicarboxylic acids, including meso-diacids, cis-1,2-cycloalkanedicarboxylic acids, and diacids with a prochiral center, was studied with 14 substrates.The products of these stereoselective hydrolyses are chiral monoesters of dicarboxylic acids, with an enantiomeric excess (e.e.) from 10percent to 100percent.Some of these optically active monoesters are valuable synthons in natural products synthesis.An additivity pattern of α- and β-substituents with the glutaric esters on the stereoselectivity of enzymatic hydrolysis was observed.Analysis of the experimental results leads to a model of enzyme stereoselectivity of diester hydrolysis in which the substitution pattern at α- and β-C-atoms is found to determine the absolute configuration of the resulting monoester.
- Mohr, Peter,Waespe-Sarcevic, Nada,Tamm, Christoph,Gawronska, Krystyna,Gawronsky, Jacek K.
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p. 2501 - 2511
(2007/10/02)
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