- Disproportionation reactions within the series of coordinated monoorganostannanes
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Interaction of monoorganotin trichlorides (RSnCl3, R = Ph, Vin, All, Bn and c-Pr) with O-TMS-amides of 2-hydroxycarboxylic acids afforded a number of mononuclear and binuclear organotin complexes (2a-j). These organotin complexes disproportionate into diorganostannanes and inorganic coordination compounds containing two O,O-chelated ligands (3a-c). All the complexes were characterized by multinuclear NMR spectroscopy in solution and X-ray diffraction in crystalline state (2a, 2b, 2j, 3b, 3c). It was found that disproportionation reaction proceeded only for very well dissolved substances in concentrated solutions upon heating. The tendency for disproportionation depends on the nature of a substituent and decreases as follow: Vin ≈ Allyl > Bn > Ph ≈ c-Pr >> Alk. It is believed that the key step of the mechanism of disproportion reaction is a ligand exchange, which is possible only in the case of binuclear complexes acting as intermediate compounds.
- Airapetyan,Petrosyan,Gruener,Zaitsev,Arkhipov,Korlyukov
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Read Online
- Reversible Formation of Alkyl Radicals at [Fe4S4] Clusters and Its Implications for Selectivity in Radical SAM Enzymes
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All kingdoms of life use the transient 5′-deoxyadenosyl radical (5′-dAdoa ) to initiate a wide range of difficult chemical reactions. Because of its high reactivity, the 5′-dAdo?must be generated in a controlled manner to abstract a specific H atom and avoid unproductive reactions. In radical S-Adenosylmethionine (SAM) enzymes, the 5′-dAdo?is formed upon reduction of SAM by an [Fe4S4] cluster. An organometallic precursor featuring an Fe-C bond between the [Fe4S4] cluster and the 5′-dAdo group was recently characterized and shown to be competent for substrate radical generation, presumably via Fe-C bond homolysis. Such reactivity is without precedent for Fe-S clusters. Here, we show that synthetic [Fe4S4]-Alkyl clusters undergo Fe-C bond homolysis when the alkylated Fe site has a suitable coordination number, thereby providing support for the intermediacy of organometallic species in radical SAM enzymes. Addition of pyridine donors to [(IMes)3Fe4S4-R]+ clusters (R = alkyl or benzyl; IMes = 1,3-dimesitylimidazol-2-ylidene) generates Ra , ultimately forming R-R coupled hydrocarbons. This process is facile at room temperature and allows for the generation of highly reactive radicals including primary carbon radicals. Mechanistic studies, including use of the 5-hexenyl radical clock, demonstrate that Fe-C bond homolysis occurs reversibly. Using these experimental insights and kinetic simulations, we evaluate the circumstances in which an organometallic intermediate can direct the 5′-dAdo?toward productive H-Atom abstraction. Our findings demonstrate that reversible homolysis of even weak M-C bonds is a feasible protective mechanism for the 5′-dAdo?that can allow selective X-H bond activation in both radical SAM and adenosylcobalamin enzymes.
- Brown, Alexandra C.,Suess, Daniel L. M.
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supporting information
p. 14240 - 14248
(2020/09/15)
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- Synthesis of Benzyltributylstannanes by the Reaction of N-Tosylhydrazones with Bu3SnH
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An efficient stannylation process with N-tosylhydrazones or directly with carbonyl compounds has been developed. A series of functionalized benzyl- and alkyltributylstannanes can be synthesized in moderate to good yields under transition-metal-free conditions. Tandem transformations involving stannylation/Stille cross-coupling reaction have been carried out without purification of the benzyltributylstannane intermediates to afford a series of diarylmethane derivatives.
- Qiu, Di,Wang, Shuai,Meng, He,Tang, Shengbo,Zhang, Yan,Wang, Jianbo
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p. 624 - 632
(2017/04/26)
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- Preparation method of alkyl tin compound or benzyl tin compound
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The invention discloses a preparation method of an alkyl tin compound or a benzyl tin compound. N-tosylhydrazones, tri-n-butyltin hydride and alkali react in an organic solvent to obtain the alkyl tin compound or the benzyl tin compound. The addition of a phase transfer catalyst can effectively promote the reaction. According to the method disclosed by the invention, it is first time that the alkyl tin compound or the benzyl tin compound is directly obtained under the mild condition from N-tosylhydrazones without transition metal, the reaction efficiency is high, the reaction cost is low, and the method has good tolerance and universality on functional groups and can be widely used for preparing the alkyl tin compound or the benzyl tin compound.
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Paragraph 0035; 0036; 0037; 0038; 0039; 0040; 0275-0344
(2017/04/03)
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- METHOD FOR PRODUCING 14 GROUP METAL LITHIUM COMPOUND
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PROBLEM TO BE SOLVED: To provide a method for quantitatively producing a group 14 metal lithium compound under a mild condition. SOLUTION: The method for producing a group 14 metal lithium compound represented by formula (4): R4-nMLin comprises reacting a compound represented by formula (1): R4-nMXn and lithium in the presence of a polycyclic aromatic compound represented by formula (2) or formula (3). [In formula (1) and formula (2), R is a hydrocarbon group; M is a metal atom selected from Si, Ge and Sn; X is a halogen atom or R3M- (R and M are the same as mentioned above); and n is 1 or 2] and [R1 is H or a hydrocarbon group; and m is an integer of 0 to 5.] SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0068
(2016/10/31)
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- Stannyl-Lithium: A Facile and Efficient Synthesis Facilitating Further Applications
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We have developed a highly efficient, practical, polycyclic aromatic hydrocarbon (PAH)-catalyzed synthesis of stannyl lithium (Sn-Li), in which the tin resource (stannyl chloride or distannyl) is rapidly and quantitatively transformed into Sn-Li reagent at room temperature without formation of any (toxic) byproducts. The resulting Sn-Li reagent can be stored at ambient temperature for months and shows high reactivity toward various substrates, with quantitative atom efficiency.
- Wang, Dong-Yu,Wang, Chao,Uchiyama, Masanobu
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supporting information
p. 10488 - 10491
(2015/09/28)
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- Ultrasound promoted Barbier reactions and Csp3-Csp2 Stille coupling for the synthesis of diarylmethanes and substituted benzophenones
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Here we present the preparation of a variety of diarylmethanes obtained via ultrasound Stille coupling under palladium catalysis between some substituted aryl compounds and benzyltributyltin compounds generated through sonicated Barbier reaction in a very short time reaction and excellent yield. The study reported below compares different methods to optimize the synthesis of usually unstable benzyltin derivatives and is another contribution to the investigation of Csp3-Csp2 coupling process involving benzyl-aryl reagents. Substituted carboxylated benzophenones were easily prepared in a very good yield by oxidation of some diarylmethanes.
- Ocampo, Romina A.,Koll, Liliana C.,Mandolesi, Sandra D.
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- Quinoxaline compounds and methods of using them
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The present invention generally relates to quinoxaline compounds having Formula 1 or Formula 2 wherein the variables are as defined herein, and methods of using them.
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Page/Page column 18
(2008/06/13)
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- Photolytic zirconium benzyl bond cleavage and subsequent aryl C-F activation in zirconium complexes of fluorinated aryl diamides
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Photolysis of Zr(C6F5NCH2CH2OCH2)2 (CH2Ph)2 at 435 nm results in formation of the metalated dimer {Zr[C6F4NCH2CH2OCH2CH 2OCH2CH2NC6F5][CH2 Ph]}2·(C7H8)2 (1), the bridging difluoride dimer {Zr[C6F5NCH2CH2OCH2CH 2OCH2CH2NC6F5][F]}2 [μ-F]2 (2), and bibenzyl. Complex 1 was characterized by NMR spectroscopy (1H, 19F, 13C) and X-ray crystallography. In the solid state 1 adopts a pentagonal bipyramidal geometry at each zirconium center with a η1-benzyl group occupying one of the axial positions. The bridging difluoride 2 was characterized by 1H and 19F NMR spectroscopy. For comparison purposes, Zr(C6F5NCH2CH2OCH2)2 Me2 (3) was synthesized and characterized by NMR spectroscopy and X-ray crystallography. Photolysis of 3 at 435 nm does not result in any reaction.
- O'Connor, Paul E.,Berg, David J.,Barclay, Tosha
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p. 3947 - 3954
(2008/10/08)
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- 8-arylalkyl- and 8-arylheteroalkyl-5,11-dihydro-6H-dipyrido?3,2-B:2',3'-e!?1!diazepines and their use in the treatment of HIV-1 infection
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Disclosed are novel 8-arylalkyl-5,11-dihydro-6H-dipyrido?3,2-b:2',3'-e!?1,4!diazepines. These are useful in the treatment of HIV-1 infection.
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- The effect of CO on the reaction of (tributyltin)lithium with alkyl and aryl bromides
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The reaction of (tributyltin)lithium with alkyl and aryl bromides in THF was studied in the presence of CO and of p-dinitrobenzene under several reaction conditions. The observed results indicate that electron transfer is involved in the substitution reac
- Nudelman, N. Sbarbati,Carro, Cecilia
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- 8-Arylalkyl- and 8-arylheteroalkyl-5, 11-dihydro-6H-dipyrido-[3,2-b:2', 3'-e][1,4]diazepines and their use in the prevention or treatment of HIV infection
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The invention relates to novel 8-arylalkyl-5,11-dihydro-6H-dipyrido[3,2-b:2',3'-e][1,4]diazepines of general formula 1 which are useful in the prevention or treatment of HIV infection.
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- Preparation of benzylstannanes by zinc-mediated coupling of benzyl bromides with organotin derivatives. Physicochemical characterization and crystal structures
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Benzyltrialkyl- (1-13) and benzyltriphenylstannanes (16-22) have been easily prepared in a one-pot synthesis via coupling reaction of benzyl bromide derivatives (C6H5CH2Br and XYC6H3CH2Br, X = H, Y = o-, m-, p-CH3, o-, m-, p-F, o-, m-Cl, and p-Br; X = o-F, Y = p-Br) with R3SnCl compounds (R = Et, Pr, Bu, and Ph) in THF/H2O (NH4Cl) medium mediated by zinc powder. Such coupling also occurs with (Bu3Sn)2O. Dibenzyldibutylstannane (15) is prepared by reaction of benzyl bromide with Bu2SnCl2 or (Bu2SnCl)2O, and (2-naphthylmethyl)tributylstannane (14) by reaction of 2-(bromomethyl)naphthalene with Bu3SnCl. 13C-and 119Sn-NMR data are reported for all compounds, and M?ssbauer data for benzyltributylstannanes 10 and 11 and benzyltriphenylstannanes 16-18 and 20-22. The crystal structures of Ph3SnBn, with Bn = o- (17) and m-ClC6H4CH2 (18) and o- (20) and m-FC6H4-CH2 (21) have been determined.
- Marton, Daniele,Russo, Umberto,Stivanello, Diego,Tagliavini, Giuseppe,Ganis, Paolo,Valle, Giovanni Carlo
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p. 1645 - 1650
(2008/10/08)
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- The preparation of pure allyl- and benzyl-type organoalkali intermediates via organotin compounds
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Superbase metalation of alkenes or alkylbenzenes and subsequent condensation with trialkylstannyl chloride affords allyl- or benzyl-type organotin compounds that can be isolated in pure form.Treatment with soluble reagents such as methyllithium, trimethylsilylmethylpotassium and trimethylsilylmethylcaesium generates the corresponding organoalkali derivatives almost quantitatively and in high purity, suitable for kinetic or spectroscopic studies.
- Desponds, Olivier,Schlosser, Manfred
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- Palladium Catalyzed Reaction of Acyltins with Organic Halides
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Palladium catalyzed reaction of acyltins with organic halides were investigated.Among the halides, acyl halides and allylic halides were good substrates, and the latter gave allylic ketones in good yields.
- Kosugi, Masanori,Naka, Hiroyuki,Harada, Saburo,Sano, Hiroshi,Migita, Toshihiko
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p. 1371 - 1372
(2007/10/02)
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- SYNTHESIS OF ORGANOTRIALKYLSTANNANES. THE REACTION BETWEEN ORGANIC HALIDES AND HEXAALKYLDISTANNANES IN THE PRESENCE OF PALLADIUM COMPLEXES
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The aryl halides YC6H4X (X=Br or I) have been shown to react with the distannanes (R3Sn)2 (R=n-Bu or Me) in toluene in the presence of or to give the compounds YC6H4SnR3 for (a) R=n-Bu, Y=H, p-OMe, o-Me, p-Me, m-Cl, p-Cl, m-CN, p-COCH3 and m-NO2, and (b) R=Me, Y=H, p-OMe, p-Me, p-CN, p-COCH3, m-NO2 and p-NO2.Benzyl halides YC6H4CH2X (X=Cl or Br) similarly give YC6H4CH2SnR3 for (a) R=n-Bu, Y=H, m-OMe, p-OMe, m-Cl, m-CN, and m-NO2, and (b) R=Me, Y=m-Cl, m-CN, p-CN and m-NO2.These reactions are of special value as preparative procedures in cases in which Grignard or organolithium reagents cannot be used.Allyl chloride and bromide were likewise shown to react with (n-Bu3Sn)2 to give CH2=CHCH2SnBu3, but n-BuCl and n-BuBr gave only a trace of n-Bu4Sn.The mixed dimetallo species n-Bu3SnSiMe3 was shown to react with aryl bromides YC6H4Br (X=H, p-OMe, p-Me, or p-Cl) to give the arylsilicon compounds YC6H4SiMe3, with no aryltin products.
- Azizian, Hormoz,Eaborn, Colin,Pidcock, Alan
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