- Metal-Free and Alkali-Metal-Catalyzed Synthesis of Isoureas from Alcohols and Carbodiimides
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The first addition of alcohols to carbodiimides catalyzed by transition-metal-free compounds employs 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and its alkali metal salts. Isoureas are obtained in short reaction times and high yields when TBDK is used as the catalyst. Control of the coordination sphere of potassium with exogenous chelating ligands, in combination with mechanistic DFT calculations, demonstrated the role and positive influence of the alkali-metal cation on the kinetics.
- Imberdis, Arnaud,Lefèvre, Guillaume,Thuéry, Pierre,Cantat, Thibault
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supporting information
p. 3084 - 3088
(2018/02/26)
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- Actinide complexes possessing six-membered N-heterocyclic iminato moieties: Synthesis and reactivity
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A novel class of ligand systems possessing a sixmembered N-heterocyclic iminato [perimidin-2-iminato (PrRN, where R = isopropyl, cycloheptyl)] moiety is introduced. The complexation of these ligands with early actinides (An = Th and U) results in powerful catalysts [(PrRN)An(N{SiMe3)2}3] (3-6) for exigent insertion of alcohols into carbodiimides to produce the corresponding isoureas in short reaction times with excellent yields. Experimental, thermodynamic, and kinetic data as well as the results of stoichiometric reactions provide cumulative evidence that supports a plausible mechanism for the reaction.
- Ghatak, Tapas,Fridman, Natalia,Eisen, Moris S.
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p. 1296 - 1302
(2017/05/29)
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- Synthetic method for isourea catalyzed by rare-earth compound
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The invention relates to a synthetic method for isourea catalyzed by a rare-earth compound. The synthetic method comprises the following steps: (1) enabling carbodiimide which is as shown in a formula (1) and alcohol which is as shown in a formula (2) to react at 25 to 60 DEG C under the catalytic action of rare earth amine to obtain the isourea, wherein the structural formulae of the formula (1) and the formula (2) are as shown in the description, wherein R1 and R2 are independently selected from C3-C8 alkyls or aryls; R3 is C1-C3 alkyls or substituted benzyls, wherein the substituted benzyls are the benzyls which contain a methyl, a naphthyl, a halogen or a pyridine ring; the rare earth amine is one of lanthanum tris[N,N-bis(trimethylsilane)amide], neodymium tris[N,N-bis(trimethylsilane)amide], samarium tris[N,N-bis(trimethylsilane)amide] or ytterbium tris[N,N-bis(trimethylsilane)amide]. According to the method, raw materials are easily obtained; the operation is simple and convenient; conditions of an application method are mild; the yield is high; the substrate application range is wide.
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Paragraph 0083; 0087; 0089-0091
(2018/03/24)
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- Actinide-Catalyzed Intermolecular Addition of Alcohols to Carbodiimides
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The unprecedented actinide-catalyzed addition of alcohols to carbodiimides is presented. This represents a rare example of thorium-catalyzed transformations of an alcoholic substrate and the first example of uranium complexes showing catalytic reactivity with alcohols. Using the uranium and thorium amides U[N(SiMe3)2]3 and [(Me3Si)2N]2An[κ2-(N,C)-CH2Si(CH3)2N(SiMe3)] (An = Th or U), alcohol additions to unsaturated carbon-nitrogen bonds are achieved in short reaction times with excellent selectivities and high to excellent yields. Computational studies, supported by experimental thermodynamic data, suggest plausible models of the profile of the reaction which allow the system to overcome the high barrier of scission of the actinide-oxygen bond. Accompanied by experimentally determined kinetic parameters, a plausible mechanism is proposed for the catalytic cycle.
- Batrice, Rami J.,Kefalidis, Christos E.,Maron, Laurent,Eisen, Moris S.
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supporting information
p. 2114 - 2117
(2016/03/05)
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- A novel synthesis of 2-alkylthiobenzothiazoles and 2-alkylthiobenzoxazoles
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3H-Benzothiazole-2-thione and 3H-benzoxazole-2-thione were selectively S-alkylated by use of O-alkylisoureas as the alkylating reagents. The reactions could be performed under mild reaction conditions in short reaction times, and high yields were obtained using O-primary-alkylisoureas, whereas low yields were obtained with sec-and tert-alkylisoureas.
- Yu, Yanfei,Li, Zhengning,Jiang, Lan
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experimental part
p. 632 - 640
(2012/06/01)
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- Regiospecific 4-O-alkylation of tetronic acids with isoureas
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4-Alkoxy-5H-furan-2-ones (4-O-alkyl tetronates) with various types of substituents at positions C-3, C-5, or C-3 and C-5 were prepared in good yields and under mild conditions from the corresponding parent tetronic acids and readily available isoureas of the respective primary or secondary alcohols. 2-O-Alkylation was not observed in any case. 4-Alkoxycoumarins are accessible likewise.
- Schobert, Rainer,Siegfried, Sven
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p. 686 - 688
(2007/10/03)
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- Inhibition of Human Leukocyte Elastase. 2. Inhibition by Substituted Cephalosporin Esters and Amides
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A variety of 7α-methoxycephalosporin ester and amide sulfones were prepared and tested to determine the structure-activity relations for inhibition of human leukocyte elastase (HLE), a serine protease which has been implicated in several degenerative lung
- Finke, Paul E.,Ashe, Bonnie M.,Knight, Wilson B.,Maycock, Alan L.,Navia, Manuel A.,et al.
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p. 2522 - 2528
(2007/10/02)
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