- Synthesis of a Sterically Demanding Dispiropiperidine and Its Application in Monoamidodialkyl Zincate Complexes
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The new sterically hindered piperidine analog, dispiro[cyclohexane-2,2′-piperidine-6′,2″-cyclohexane] (CPC(H), 2), and its N-methylated derivative CPC(Me) (3) were synthesized from commercially available starting materials in short steps. The N-lithiated amide LiCPC (4) was also isolated from 2 as a cyclictrimer in single crystals and showed slightly larger steric hindrance than that of lithium 2,2,6,6-tetramethylpiperidide (LiTMP) in the competitive methylation reaction with methyl trifluoromethanesulfonate. In addition, the heterobimetallic heteroleptic zincate complexes [Li(μ-NR2)(μ-Et)Zn(Et)] (NR2 = CPC, 5, and NR2 = TMP, 6) were obtained as THF- and TMEDA-coordinated monomer 5·(THF)2, 6·(THF)2, 5·TMEDA, and 6·TMEDA (THF = tetrahydrofuran, TMEDA = N,N,N′,N′-tetramethylethylenediamine). These molecular structures bearing different amido ligands in single crystals showed little structural differences from crystallographic studies. Diffusion-ordered spectroscopy (DOSY) revealed that the solution structures of the zincate complexes 5·(THF)2 and 6·(THF)2 only differ in the number of coordination THF molecules. In the deprotonation reactions with tert-butyl 3-bromobenzoate, the zincate complexes containing the CPC ligand [Li(μ-CPC)(μ-R)Zn(R)] (R = Et (5), tBu) showed moderately improved regioselectivity for the 6 position in comparison to those containing the TMP ligand [Li(μ-TMP)(μ-R)Zn(R)] (R = Et (6), tBu).
- Morisako, Shogo,Shang, Rong,Yamamoto, Yohsuke
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- Alkyl-Substituted Selenium-Bridged V-Shaped Organic Semiconductors Exhibiting High Hole Mobility and Unusual Aggregation Behavior
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Toward the development of high-performance organic semiconductors (OSCs), carrier mobility is the most important requirement for next-generation OSC-based electronics. The strategy is that OSCs consisting of a highly extended ?-electron core exhibit two-dimensional (2D) aggregated structures to offer effective charge transport. However, such OSCs, in general, show poor solubility in common organic solvents, resulting in limited solution processability. This is a critical trade-off between the development of OSCs with simultaneous high carrier mobility and suitable solubility. To address this issue, herein, five-membered ring-fused selenium-bridged V-shaped binaphthalene with decyl substituents (C10-DNS-VW) is developed and synthesized by an efficient method. C10-DNS-VW exhibits significantly high solubility for solution processes. Notably, C10-DNS-VW forms a one-dimensional ?-stacked packing motif (1D motif) and a 2D herringbone (HB) packing motif (2D motif), depending on the crystal growth condition. On the other hand, the fabrication of thin films by means of both solution process and vacuum deposition techniques forms only the 2D HB motif. External stress tests such as heating and exposure to solvent vapor indicated that 1D and 2D motifs could be synergistically induced by the total balance of intermolecular interactions. Finally, the single-crystalline films of C10-DNS-VW by solution process exhibit carrier mobility up to 11 cm2 V-1 s-1 with suitable transistor stability under ambient conditions for more than two months, indicating that C10-DNS-VW is one of the most promising candidates for breaking the trade-off in the field of solution-processed technologies.
- Okamoto, Toshihiro,Mitani, Masato,Yu, Craig P.,Mitsui, Chikahiko,Yamagishi, Masakazu,Ishii, Hiroyuki,Watanabe, Go,Kumagai, Shohei,Hashizume, Daisuke,Tanaka, Shota,Yano, Masafumi,Kushida, Tomokatsu,Sato, Hiroyasu,Sugimoto, Kunihisa,Kato, Takashi,Takeya, Jun
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- Three-Component Difunctionalization of Cyclohexenyl Triflates: Direct Access to Versatile Cyclohexenes via Cyclohexynes
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Difunctionalization of strained cyclic alkynes presents a powerful strategy to build richly functionalized cyclic alkenes in an expedient fashion. Herein we disclose an efficient and flexible approach to achieve carbohalogenation, dicarbofunctionalization, aminohalogenation and aminocarbonation of readily available cyclohexenyl triflates. We have demonstrated the novel use of zincate base/nucleophile system for effective formation of key cyclohexyne intermediates and selective addition of various carbon and nitrogen nucleophiles. Importantly, leveraging the resulting organozincates enables the incorporation of a broad range of electrophilic partners to deliver structurally diverse cyclohexene motifs. The importance and utility of this method is also exemplified by the modularity of this approach and the ease in which even highly complex polycyclic scaffolds can be accessed in one step.
- Cho, Seoyoung,McLaren, E. J.,Wang, Qiu
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supporting information
p. 26332 - 26336
(2021/11/10)
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- Direct Hydroxylation and Amination of Arenes via Deprotonative Cupration
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Deprotonative directed ortho cupration of aromatic/heteroaromatic C-H bond and subsequent oxidation with t-BuOOH furnished functionalized phenols in high yields with high regio- and chemoselectivity. DFT calculations revealed that this hydroxylation reaction proceeds via a copper (I → III → I) redox mechanism. Application of this reaction to aromatic C-H amination using BnONH2 efficiently afforded the corresponding primary anilines. These reactions show broad scope and good functional group compatibility. Catalytic versions of these transformations are also demonstrated.
- Tezuka, Noriyuki,Shimojo, Kohei,Hirano, Keiichi,Komagawa, Shinsuke,Yoshida, Kengo,Wang, Chao,Miyamoto, Kazunori,Saito, Tatsuo,Takita, Ryo,Uchiyama, Masanobu
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supporting information
p. 9166 - 9171
(2016/08/05)
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- METHODS FOR PREPARING DIORGANOZINC COMPOUNDS
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There are provided methods for preparing the diorganozmc compounds of formula R2Zn (I or Ia), where R is a defined organic radical, and the two R groups can be the same or different The starting material is the zinc compound ZnX2 (II) or R2ZnX (IIa), where X is a defined anion and R2 is a defined organic radical. The zinc reagent of type II is combined with a Grignard reagent and also, when X is Cl or Br, with an alkali metal reagent (VI) to form the diorganozinc product (I or Ia). Also provided are methods for preparing the zinc alcoholates of formula Zn(OR1)2 by reaction of ZnX2, where X = Cl or Br, with an alkali metal reagent of the formula MOR1, where M = Na or K, and where R1 is a defined organic radical.
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Page/Page column 19-20
(2009/01/20)
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- Synthesis and structures of new binuclear zinc alkyl, aryl and aryloxo complexes
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The synthesis of a series of binuclear zinc complexes with Cl, N and O bridges is reported. The reaction of EtZnCl with B(C6F5)3 in the presence of hexamethylbenzene affords the arene complex [Zn(μ-Cl)(C6F5)(η-C6Me6)]2 in which the C6Me6 ligand may be regarded as η3-bonded. The comproportionation of Zn[N(SiMe3)2]2 with ZnBut2 or Zn(C6F5)2 · toluene gave [ButZn{μ-N(SiMe3)2}]2 and [C6F5Zn{μ-N(SiMe3)2}]2, respectively, with three-coordinate zinc. The reaction of ZnEt2 with C6F5OH in the presence of pyridine gave [EtZn(μ-OC6F5)(py)]2, while ZnMe2 and C6F5OH followed by recrystallisation from THF gave [Zn(OC6F5)(μ-OC6F5)(THF)2]2 with five-coordinate zinc in a trigonal-bipyramidal geometry. The structures of these compounds have been determined.
- Sarazin, Yann,Wright, Joseph A.,Harding, Duncan A.J.,Martin, Eddy,Woodman, Timothy J.,Hughes, David L.,Bochmann, Manfred
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p. 1494 - 1501
(2008/09/18)
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- Copper-Catalyzed Electrophilic Amination of Diorganozinc Reagents
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The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, ≤1 h) and ease of product isolation (acid/base extractive workup). Copyright
- Berman, Ashley M.,Johnson, Jeffrey S.
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p. 5680 - 5681
(2007/10/03)
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- Coordination to RMg+ and RZn+ cations
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Addition of a second coordinating agent (coord*) to a solution of RM(coord)+A- (R = ethyl or neopentyl, M = Zn or Mg, A- = 1,2,3,4-tetraphenylcyclopentadienyl) can provide equilibrium mixtures of these compounds, coord, and RM(coord*)+A-. This exchange with RMg(coord)+ requires the addition of a small amount of R2Mg, but added R2Zn is not necessary for exchanges with RZn(coord)+. The equilibrium constants provide information about the relative abilities of different coordinating agents to coordinate to RM+ and reveal significant differences between coordination to RMg+ and RZn+. Reactions of RM(coord)+ with R′2M (R = ethyl or neopentyl for RMg(coord)+ and ethyl, isopropyl, tert-butyl, neopentyl, or p-methylphenyl for RZn(coord)+) provide equilibrium mixtures of these components, R′M(coord)+, and R2M. The equilibrium constants provide information about the effect of R on stability. An X-ray structure of p-methylphenylzinc(2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane)+ shows that just three of the N atoms are coordinated to Zn. The effects of coord, R, and metal on RM(coord)+ stability are discussed, and the abilities of coordinating agents to coordinate to RM+, to slow allylic isomerization of (CH2 double bond CMeCH2)2Zn, and to convert R2Zn to RZn(coord)+ are compared.
- Tang, Hui
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p. 4810 - 4819
(2008/10/08)
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- Design, reactivities, and practical application of dialkylzinc hydride ate complexes generated in Situ from dialkylzinc and metal hydride. A new methodology for activation of NaH and LiH under mild conditions
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We designed various dialkylzinc hydride 'ate' complexes, prepared from dialkylzinc and metal hydride, and investigated the reactivities (and the transference aptitude of ligands) of these zincates toward benzophenone. The results clearly reveal that dimethylzinc hydrides are the most powerful and selective zincates for the reduction of the carbony1 group. This complex reagent turned out to be effective for the reduction of esters and amides as well as aldehydes and ketones to the corresponding alcohols and amines with good to excellent yields under mild conditions. Furthermore, the method was successfully used for the highly selective 1,2-reduction of α,β-unsaturated carbonyl compounds, the regioselective ring-opening reduction of epoxides, and the chemoselective reduction of aldehydes in the presence of ketones. We also discuss and clarify the active species and the mechanism of this reduction using the diastereoselective reductions of some carbonyl compounds with an adjacent chiral center. Also, this reducing system was found to constitute a powerful tool for the stereoselective synthesis of syn- and anti-1,2-diols. Moreover, we developed the catalytic version of this reducing system. The LiH-Me2Zn-ultrasound system proved to be effective not only for the catalytic reduction of the carbonyl compounds and epoxides but also for the partial reduction (the conversion) of carboxylic acids to aldehydes. This system is a very attractive method for several reasons (good availability, low cost, and easy operation) and would be particularly useful for large- scale reductions.
- Uchiyama, Masanobu,Furumoto, Shozo,Saito, Mariko,Kondo, Yoshinori,Sakamoto, Takao
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p. 11425 - 11433
(2007/10/03)
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