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Mehwish Naz, Toby Hallam, Nina C Berner, Niall McEvoy, Riley Gatensby, John B McManus, Zareen Akhter, Georg S Duesberg
We report on 2H-2H'/1T phase conversion of MoS2 and MoSe2 polycrystalline films grown by thermally assisted conversion. The structural conversion of the transition metal dichalcogenides was successfully carried out by organolithium treatment on chip. As a result we obtained a new 2H-2H'/1T co-phase system of the TMDs thin films which was verified by Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The conversion was successfully carried to on selected areas yielding a lateral heterostructure between the pristine 2H phase and the 2H'/1T co-phase regions...
October 24, 2016: ACS Applied Materials & Interfaces
Ze-Kun Yang, Dong-Yu Wang, Hiroki Minami, Hiroyuki Ogawa, Takashi Ozaki, Tatsuo Saito, Kazunori Miyamoto, Chao Wang, Masanobu Uchiyama
Various aryl-, alkenyl-, and/or alkyllithium species reacted smoothly with aryl and/or benzyl ethers with cleavage of the inert C-O bond to afford cross-coupled products, catalyzed by commercially available [Ni(cod)2 ] (cod=1,5-cyclooctadiene) catalysts with N-heterocyclic carbene (NHC) ligands. Furthermore, the coupling reaction between the aryllithium compounds and aryl ammonium salts proceeded under mild conditions with C-N bond cleavage in the presence of a [Pd(PPh3 )2 Cl2 ] catalyst. These methods enable selective sequential functionalizations of arenes having both C-N and C-O bonds in one pot...
September 15, 2016: Chemistry: a European Journal
Rocío Velasco, Carlos Silva López, Olalla Nieto Faza, Roberto Sanz
By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups...
October 10, 2016: Chemistry: a European Journal
Vittorio Pace, Serena Monticelli, Karen de la Vega-Hernández, Laura Castoldi
The addition of carbon (Grignard and organolithium reagents) and hydride nucleophiles (Schwartz reagent) to isocyanates and isothiocyanates constitutes a versatile, direct and high yielding approach to the synthesis of functionalized (thio)amide derivatives including haloamides and formamides. The chemoselective delivery of a nucleophilic (eventually configurationally stable) organometallic species to a given iso(thio)cyanate is the crucial parameter for the success of the strategy. Thus, the influence of the factors governing classical methodologies (e...
August 16, 2016: Organic & Biomolecular Chemistry
Andreas Hafner, Mark Meisenbach, Joerg Sedelmeier
The benefits and limitations of a simple continuous flow setup for handling and performing of organolithium chemistry on the multigram scale is described. The developed metalation platform embodies a valuable complement to existing methodologies, as it combines the benefits of Flash Chemistry (chemical synthesis on a time scale of <1 s) with remarkable throughput (g/min) while mitigating the risk of blockages.
August 5, 2016: Organic Letters
Ling Chen, Jian Cao, Zheng Xu, Zhan-Jiang Zheng, Yu-Ming Cui, Li-Wen Xu
A family of four-membered enones, polysubstituted alkylidenecyclobutenones, were easily prepared by a Lewis acid catalyzed [2+2] cycloaddition of ynamides and propargyl silyl ethers. This challenging regioselective [2+2] cycloaddition enables the efficient construction and conversion of four-membered enones, which provides high-value and structurally diverse products through the unexpected ring-opening and ring expansion of alkylidenecyclobutenone with Grignard reagents, organolithium, primary amines, and water...
July 21, 2016: Chemical Communications: Chem Comm
Ross Davidson, Yu-Ting Hsu, Thomas Batchelor, Dmitry Yufit, Andrew Beeby
A versatile palladium-free route for the synthesis of 4-aryl-substituted phenylpyridines (ppy), starting from tert-butyl 4-oxopiperidine-1-carboxylate, is reported. Reaction with an aryllithium, followed by trifluoroacetic acid dehydration/deprotection and oxidation with 2-iodoylbenzoic acid and finally phenylation, gave 4 ligands (L(1-4)H): 2,4-diphenylpyridine, 4-(4-methoxyphenyl)-2-phenylpyridine, 2-phenyl-4-(o-tolyl)pyridine and 4-mesityl-2-phenylpyridine. These ligands were coordinated to iridium to give the corresponding Ir(L)2(A) complexes (Ir1-7), where A = ancillary ligand acetylacetate or 2-picolinate...
July 28, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Zhenhua Jia, Qiang Liu, Xiao-Shui Peng, Henry N C Wong
No abstract text is available yet for this article.
2016: Nature Communications
Erik B Pinxterhuis, Massimo Giannerini, Valentín Hornillos, Ben L Feringa
Although the use of catalytic rather than stoichiometric amounts of metal mediator in cross-coupling reactions between organic halides and organometallic counterparts improves significantly the atom economy and waste production, the use of solvents and stoichiometric generation of main-group byproducts (B, Sn and Zn) hamper the 'greenness' and industrial efficiency of these processes. Here we present a highly selective and green Pd-catalysed cross-coupling between organic halides and organolithium reagents proceeding without additional solvents and with short reaction times (10 min)...
2016: Nature Communications
Yu-Xiang Chen, Chien-Wei Wu, Ting-Yang Kuo, Yu-Lung Chang, Ming-Hsing Jen, I-Wen Peter Chen
To progress from laboratory research to commercial applications, it is necessary to develop an effective method to prepare large quantities and high-quality of the large-size atomically thin molybdenum dichalcogenides (MoS2). Aqueous-phase processes provide a viable method for producing thin MoS2 sheets using organolithium-assisted exfoliation; unfortunately, this method is hindered by changing pristine semiconducting 2H phase to distorted metallic 1T phase. Recovery of the intrinsic 2H phase typically involves heating of the 1T MoS2 sheets on solid substrates at high temperature...
2016: Scientific Reports
Vittorio Pace, Irene Murgia, Sophie Westermayer, Thierry Langer, Wolfgang Holzer
An efficient, chemoselective homologation of Weinreb amides to the corresponding variously substituted α-oxyketones has been developed via the addition of lithiated α-oxygenated species. This one-step, experimentally easy, high yielding protocol is amenable not only for accessing simple α-oxyketones but also for more complex substituted ones ranging from primary and secondary alkyl-type to aromatic ones. Full delivery of the stereochemical information contained in the starting materials is observed through both the employment of enantioenriched Weinreb amides and optically active organolithium species...
June 18, 2016: Chemical Communications: Chem Comm
Danny C Lenstra, Vincent Vedovato, Emmanuel Ferrer Flegeau, Jonathan Maydom, Michael C Willis
A one-pot process for the synthesis of unsymmetrical sulfoxides using organometallic nucleophiles is described. Sulfur dioxide, delivered from the surrogate DABSO (DABCO-bis(sulfur dioxide)), acts as the initial electrophile and combines with the first organometallic reagent to generate a sulfinate intermediate. In situ conversion of the sulfinate to a sulfinate silyl ester, using TMS-Cl (trimethylsilyl chloride), generates a second electrophile, allowing addition of a second organometallic reagent. Organolithium or Grignard reagents can be employed, delivering sulfoxides in good to excellent yields...
May 6, 2016: Organic Letters
Aiichiro Nagaki, Yusuke Takahashi, Jun-Ichi Yoshida
Using a flow microreactor system, carbamoyllithium compounds were successfully generated and used for reactions with electrophiles to give various amides, including α-ketoamides. The present method could be applied to the three-component synthesis of functionalized α-ketoamides using a carbamoyllithium compound, methyl chloroformate, and a functionalized organolithium reagent.
April 18, 2016: Angewandte Chemie
Nicolas E S Guisot, Idriss Ella Obame, Prathap Ireddy, Arnaud Nourry, Christine Saluzzo, Gilles Dujardin, Didier Dubreuil, Muriel Pipelier, Stéphane Guillarme
A new strategy for the synthesis of acyl β-C-glycosides is described. The reactivity of glyconitriles toward organometallic reagents such as organomagnesium or organolithium derivatives was studied, affording acyl β-C-glycosides in moderate to good yields. In this study, glycal formation was efficiently prevented by deprotonating the hydroxyl group in position 2 of the glyconitriles during the process.
March 18, 2016: Journal of Organic Chemistry
Zhenhua Jia, Qiang Liu, Xiao-Shui Peng, Henry N C Wong
In past decades, catalytic cross-coupling reactions between organic halides and organometallic reagents to construct carbon-carbon bond have achieved a tremendous progress. However, organolithium reagents have rarely been used in cross-coupling reactions, due mainly to their high reactivity. Another limitation of this transformation using organolithium reagents is how to control reactivity with excellent selectivity. Although palladium catalysis has been applied in this field recently, the development of an approach to replace catalytic systems of noble metals with nonprecious metals is currently in high demand...
2016: Nature Communications
Vittorio Pace, Azzurra Pelosi, Daniele Antermite, Ornelio Rosati, Massimo Curini, Wolfgang Holzer
An efficient, chemoselective homologation of disulfides and diselenides to the corresponding dithio- and diselenoacetals has been developed via the addition of bromomethyllithium. Chemoselectivity is fully preserved in the presence of concomitant electrophilic sites decorating the substrates. The synthetic potential of selected dithioacetals has been evaluated in Feringa-Fañanas-Mastral-type Pd-catalyzed coupling with an organolithium and in the unusual 1,4-addition to a Weinreb amide.
February 11, 2016: Chemical Communications: Chem Comm
Liang Zhang, Gabriel J Lovinger, Emma K Edelstein, Adam A Szymaniak, Matteo P Chierchia, James P Morken
Transition metal catalysis plays a central role in contemporary organic synthesis. Considering the tremendously broad array of transition metal-catalyzed transformations, it is remarkable that the underlying elementary reaction steps are relatively few in number. Here, we describe an alternative to the organometallic transmetallation step that is common in many metal-catalyzed reactions, such as Suzuki-Miyaura coupling. Specifically, we demonstrate that vinyl boronic ester ate complexes, prepared by combining organoboronates and organolithium reagents, engage in palladium-induced metallate rearrangement wherein 1,2-migration of an alkyl or aryl group from boron to the vinyl α-carbon occurs concomitantly with C-Pd σ-bond formation...
January 1, 2016: Science
Dorus Heijnen, Jean-Baptiste Gualtierotti, Valentín Hornillos, Ben L Feringa
Nickel-catalyzed selective cross-coupling of aromatic electrophiles (bromides, chlorides, fluorides and methyl ethers) with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene (NHC) complex allows the reaction with a variety of (hetero)aryllithium compounds, including those prepared via metal-halogen exchange or direct metallation, whereas a commercially available electron-rich nickel-bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product...
March 14, 2016: Chemistry: a European Journal
Sureshbabu Guduguntla, Valentín Hornillos, Romain Tessier, Martín Fañanás-Mastral, Ben L Feringa
A highly enantioselective copper/N-heterocyclic carbene catalyzed allylic arylation with organolithium compounds is presented. The use of commercial or readily prepared aryllithium reagents in the reaction with allyl bromides affords a variety of chiral diarylvinylmethanes, comprising a privileged structural motif in pharmaceuticals, in high yields with good to excellent regio- and enantioselectivities. The versatility of this new transformation is illustrated in the formal synthesis of the marketed drug tolterodine (Detrol)...
January 15, 2016: Organic Letters
M Giannerini, C Vila, V Hornillos, B L Feringa
An efficient sequential 1,2-addition/cross-coupling of Weinreb amides with two organolithium reagents is reported. This synthetic approach allows access to a wide variety of functionalized ketones in a modular way. The one-pot procedure presented here takes advantage of a kinetically stable tetrahedral Weinreb intermediate during subsequent Pd-catalyzed cross-coupling with the second organolithium reagent leading, within short reaction times and under mild conditions, to the formation of ketones in excellent overall yields...
January 21, 2016: Chemical Communications: Chem Comm
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