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https://www.readbyqxmd.com/read/28295938/alkenyl-isocyanide-conjugate-additions-a-rapid-route-to-%C3%AE-carbolines
#1
Sergiy V Chepyshev, J Armando Lujan-Montelongo, Allen Chao, Fraser F Fleming
Isocyanides are exceptional building blocks, the wide deployment of which in multicomponent and metal-insertion reactions belies their limited availability. The first conjugate addition/alkylation to alkenyl isocyanides is described, which addresses this deficiency. An array of organolithiums, magnesiates, enolates, and metalated nitriles add conjugately to β- and β,β-disubstituted arylsulfonyl alkenyl isocyanides to rapidly assemble diverse isocyanide scaffolds. The intermediate metalated isocyanides are efficiently trapped with electrophiles to generate substituted isocyanides incorporating contiguous tri- and tetra-substituted centers...
March 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28235381/stereoselective-arylation-of-amino-aldehydes-overriding-natural-substrate-control-through-chelation
#2
Bruna S Martins, Angélica V Moro, Diogo S Lüdtke
The chelation-controlled arylation reaction of chiral, enantiopure acyclic α-amino aldehydes enabled by a B/Zn exchange reaction between arylboronic acids and Et2Zn is reported. The presence of dibenzyl substituents at the nitrogen plays a key role in the stereochemical outcome of the reaction, and chelation is favored over the natural tendency of this type of substrate to undergo Felkin-Anh controlled additions with organomagnesium and organolithium reagents.
March 3, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28230375/three-component-coupling-of-triflyloxy-substituted-benzocyclobutenones-organolithium-reagents-and-arynophiles-promoted-by-generation-of-aryne-via-carbon-carbon-bond-cleavage
#3
Keisuke Uchida, Suguru Yoshida, Takamitsu Hosoya
Treatment of benzocyclobutenones bearing a triflyloxy group adjacent to the four-membered ring with organolithium reagents in the presence of arynophiles efficiently affords three-component coupled α-arylketones. Mechanistic studies indicate that the reaction is promoted by generation of the aryne via carbon-carbon bond cleavage of a benzocyclobutenoxide intermediate, which led us to find a fluoride-mediated aryne generation method from triflyloxy-substituted benzocyclobutenone silyl acetal precursors.
February 23, 2017: Organic Letters
https://www.readbyqxmd.com/read/28194863/oxygen-activated-palladium-nanoparticle-catalyzed-ultrafast-cross-coupling-of-organolithium-reagents
#4
Dorus Heijnen, Filippo Tosi, Carlos Vila, Marc C A Stuart, Philip H Elsinga, Wiktor Szymanski, Ben L Feringa
The discovery of an ultrafast cross-coupling of alkyl- and aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with reaction times ranging from 5 s to 5 min are thus generated in situ. High selectivities were observed for a range of heterocycles and functional groups as well as for an expanded scope of organolithium reagents...
March 13, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28151465/cu-catalyzed-enantioselective-allylic-alkylation-with-organolithium-reagents
#5
Valentín Hornillos, Sureshbabu Guduguntla, Martín Fañanás-Mastral, Manuel Pérez, Pieter H Bos, Alena Rudolph, Syuzanna R Harutyunyan, Ben L Feringa
This protocol describes a method for the catalytic enantioselective synthesis of tertiary and quaternary carbon stereogenic centers, which are widely present in pharmaceutical and natural products. The method is based on the direct reaction between organolithium compounds, which are cheap, readily available and broadly used in chemical synthesis, and allylic electrophiles, using chiral copper catalysts. The methodology involves the asymmetric allylic alkylation (AAA) of allyl bromides, chlorides and ethers with organolithium compounds using catalyst systems based on Cu-Taniaphos and Cu-phosphoramidites...
March 2017: Nature Protocols
https://www.readbyqxmd.com/read/28111913/catalytic-double-carbon-boron-bond-formation-for-the-synthesis-of-cyclic-diarylborinic-acids-as-versatile-building-blocks-for-%C3%AF-extended-heteroarenes
#6
Takuya Igarashi, Mamoru Tobisu, Naoto Chatani
The first catalytic synthesis of cyclic diarylborinic acids is developed using a dihydroaminoborane reagent as the boron source. Unlike previously reported methods that use organolithium reagents, this method allows the easy synthesis of cyclic diarylborinic acids bearing a range of functionalities including CN, CO2 Et, CONEt2 and NMeCO2(t) Bu. Furthermore, these cyclic diarylborinic acids provide rapid access to skeletal diversity, in particular they enable the synthesis of six- to nine-membered π-extended heteroarenes through simple cross-coupling reactions, which are important synthetic targets in both advanced materials and pharmaceuticals...
January 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28099031/stereospecific-intramolecular-arylation-of-2-and-3-pyridyl-substituted-alkylamines-via-configurationally-stable-%C3%AE-pyridyl-organolithiums
#7
Julien Maury, Wojciech Zawodny, Jonathan Clayden
Treatment of N'-aryl urea derivatives of enantiomerically enriched α-(2-pyridyl) and α-(3-pyridyl)alkylamines with a base leads to the migration of the N'-aryl substituent from N to C in a 'nonclassical' intramolecular nucleophilic aromatic substitution reaction. Both electron-rich and -poor rings migrate successfully. A new quaternary stereogenic center is formed adjacent to the pyridine ring with high stereospecificity, even when the intermediate anion is a presumably planar 2-picolyllithium. Base hydrolysis of the urea gives enantiomerically enriched α-pyridylalkylamines...
January 18, 2017: Organic Letters
https://www.readbyqxmd.com/read/27978636/formation-of-seven-membered-carbocycles-via-7-endo-mode-cyclization-of-lithioheptatrienes
#8
Ken-Ichiro Kanno, Eri Igarashi, Yuki Mizukami, Kiyohiko Nakajima, Zhiyi Song, Tamotsu Takahashi
The highly selective synthesis of triene derivatives was achieved by a zirconocene-mediated three-component coupling reaction, and the trienes were efficiently subjected to 7-endo mode cyclization. The reaction of unsymmetrical zirconacyclopentadienes prepared from two different alkynes with N-bromosuccinimide (NBS) followed by treatment with allyl halides in the presence of CuCl afforded the corresponding heptatrienes in good yields. When the trienes reacted with an organolithium reagent, 7-endo mode cyclization occurred smoothly to give the corresponding cycloheptadiene...
December 16, 2016: Organic Letters
https://www.readbyqxmd.com/read/27911386/a-protocol-for-safe-lithiation-reactions-using-organolithium-reagents
#9
Michael R Gau, Michael J Zdilla
Organolithium reagents are powerful tools in the synthetic chemist's toolbox. However, the extreme pyrophoric nature of the most reactive reagents warrants proper technique, thorough training, and proper personal protective equipment. To aid in the training of researchers using organolithium reagents, a thorough, step-by-step protocol for the safe and effective use of tert-butyllithium on an inert gas line or within a glovebox is described. As a model reaction, preparation of lithium tert-butyl amide by the reaction of tert-butyl amine with one equivalent of tert-butyl lithium is presented...
November 12, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27891818/exploiting-deep-eutectic-solvents-and-organolithium-reagent-partnerships-chemoselective-ultrafast-addition-to-imines-and-quinolines-under-aerobic-ambient-temperature-conditions
#10
Cristian Vidal, Joaquín García-Álvarez, Alberto Hernán-Gómez, Alan R Kennedy, Eva Hevia
Shattering the long-held dogma that organolithium chemistry needs to be performed under inert atmospheres in toxic organic solvents, chemoselective addition of organolithium reagents to non-activated imines and quinolines has been accomplished in green, biorenewable deep eutectic solvents (DESs) at room temperature and in the presence of air, establishing a novel and sustainable access to amines. Improving on existing methods, this approach proceeds in the absence of additives; occurs without competitive enolization, reduction or coupling processes; and reactions were completed in seconds...
December 23, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27860115/jos%C3%A3-barluenga-1940-2016
#11
José M González, Kilian Muñiz
José Barluenga, emeritus professor at the University of Oviedo, passed away on September 7, 2016. Barluenga was one of the leading Spanish chemists of his generation, with research interests including metal-mediated activation of alkenes and alkynes, β-functionalized organolithium compounds, iodination reactions, asymmetric Diels-Alder reactions, carbene complexes, and cross-coupling reactions.
November 11, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27775313/a-new-2h-2h-1t-cophase-in-polycrystalline-mos2-and-mose2-thin-films
#12
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 cophase 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 out on selected areas yielding a lateral heterostructure between the pristine 2H phase and the 2H'/1T cophase regions...
November 16, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27629250/cross-coupling-of-organolithium-with-ethers-or-aryl-ammonium-salts-by-c-o-or-c-n-bond-cleavage
#13
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
https://www.readbyqxmd.com/read/27592551/exploring-the-reactivity-of-%C3%AE-lithiated-aryl-benzyl-ethers-inhibition-of-the-1-2-wittig-rearrangement-and-the-mechanistic-proposal-revisited
#14
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
https://www.readbyqxmd.com/read/27461156/isocyanates-and-isothiocyanates-as-versatile-platforms-for-accessing-thio-amide-type-compounds
#15
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
https://www.readbyqxmd.com/read/27404123/flow-chemistry-on-multigram-scale-continuous-synthesis-of-boronic-acids-within-1-s
#16
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
https://www.readbyqxmd.com/read/27387596/lewis-acid-catalyzed-2-2-cycloaddition-of-ynamides-and-propargyl-silyl-ethers-synthesis-of-alkylidenecyclobutenones-and-their-reactivity-in-ring-opening-and-ring-expansion
#17
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
https://www.readbyqxmd.com/read/27346376/the-use-of-organolithium-reagents-for-the-synthesis-of-4-aryl-2-phenylpyridines-and-their-corresponding-iridium-iii-complexes
#18
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
https://www.readbyqxmd.com/read/27297935/corrigendum-iron-catalysed-cross-coupling-of-organolithium-compounds-with-organic-halides
#19
Zhenhua Jia, Qiang Liu, Xiao-Shui Peng, Henry N C Wong
No abstract text is available yet for this article.
2016: Nature Communications
https://www.readbyqxmd.com/read/27251636/fast-greener-and-scalable-direct-coupling-of-organolithium-compounds-with-no-additional-solvents
#20
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
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