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Qiongli Zhao, Linning Ren, Jiao Hou, Wenquan Yu, Junbiao Chang
A novel annulation reaction of N-(het)aroyldiazenes and isothiocyanates has been established. This transformation involves a sequential cyclization and desulfurization/intramolecular rearrangement to produce 2-imino-1,3,4-oxadiazolines. The less-stable N-(het)aroyldiazenes can be conveniently generated in situ by I2 -mediated oxidation of hydrazides, which allows a one-pot synthesis of the products directly from readily accessible hydrazide and isothiocyanate substrates. This operationally simple synthetic process requires no use of malodorous isocyanides and can be conveniently conducted on a gram scale...
December 14, 2018: Organic Letters
Milad Motaghi, Hormoz Khosravi, Saeed Balalaie, Frank Rominger
An unprecedented catalytic isocyanide-based cycloaddition of alkyl and aryl isocyanides with (Z)-2-(2-hydroxy-2-alkylvinyl)quinoline-3-carbaldehydes was developed for the direct and efficient synthesis of 1H-cyclopenta[b]quinolin-1-one derivatives. On the basis of DFT calculations, a mechanism is proposed involving formal [4 + 1] cycloaddition of isocyanides, followed by imine-enamine tautomerization and air oxidation.
December 12, 2018: Organic & Biomolecular Chemistry
Yuwen Wang, Arseni Kostenko, Terrance J Hadlington, Marcel-Philip Luecke, Shenglai Yao, Matthias Driess
While the transformation of carbon monoxide to multicarbon compounds (fuels and organic bulk chemicals) via reductive scission of the enormously strong CO bond is dominated by transition-metals, splitting and deoxygenative reductive coupling of CO under nonmatrix conditions using silicon, the second most abundant nonmetal of the Earth's crust, is extremely scarce and mechanistically not well understood. Herein we report the selective deoxygena-tive homocoupling of carbon monoxide by divalent silicon utilizing the (LSi:)2Xant 1a (Xant = 9,9-dimethyl-xanthene-4,5-diyl; L = PhC(NtBu)2) and (LSi:)2Fc 1b (Fc = 1,1'-ferrocenyl) as four-electron reduction reagents under mild reaction conditions (RT, 1 atm), affording the corresponding disilylketenes, Xant(LSi)2(µ-O)(µ-CCO) 2a and Fc(LSi)2(µ-O)(µ-CCO) 2b, respectively...
December 5, 2018: Journal of the American Chemical Society
Marta Serafini, Tracey Pirali
Despite benzyne has been known since 1940, this fascinating species has received much attention only over the last decades. The renaissance of interest in aryne chemistry is ascribable to the seminal discovery that arynes can be generated in situ from stable and commercially available precursors under mild and neutral conditions. Thanks to their high reactivity, arynes are key intermediates in countless chemical transformations ranging from cycloadditions to insertions and, among all these approaches, multicomponent reactions (MCRs) are currently standing out in this field...
November 2018: Drug Discovery Today. Technologies
Cecilia I Attorresi, Evelyn L Bonifazi, Javier A Ramírez, Gabriel F Gola
A pseudo-five-multicomponent reaction involving an isocyanide, a primary amine, two molecules of formaldehyde and water is reported, which gives N,N'-substituted 4-imidazolidinones when trifluoroethanol is used as the solvent. The reaction proceeds with good yields and with a wide variety of amines and isocyanides, providing an efficient new entry to these heterocycles. A preliminary study of the reaction mechanism suggests that trifluoroethanol, although acting as the solvent, is directly involved as a reagent in the reaction pathway...
November 28, 2018: Organic & Biomolecular Chemistry
Shabnam Shaabani, Alexander Dömling
Finally stereoselective: Enantioselective variations have been developed for many multicomponent reactions; however, it has been missing for the Ugi four-component reaction. This has now changed with the discovery of an efficient catalytic enantioselective variant for the four-component reaction of isocyanides, primary amines, aldehydes or ketones, and carboxylic acids.
November 15, 2018: Angewandte Chemie
Niccolò Bartalucci, Leonardo Belpassi, Fabio Marchetti, Guido Pampaloni, Stefano Zacchini, Gianluca Ciancaleoni
We recently reported a density functional theory (DFT) analysis of the Nb(V)-C bond in various NbCl5 (L) complexes, discovering that the carbon ligand L receives electronic density from the metal (classical back-donation) and from the chlorides in the cis position (direct interligand interaction). Here we report the synthesis and the structural characterization of two new coordination compounds of niobium pentahalides, i.e., NbX5 (CNXyl) (X = Cl, Br; Xyl = 2,6-C6 H3 Me2 ), and the corresponding DFT analyses of the Nb(V)-C bond using the Natural Orbitals for Chemical Valence-Charge Displacement (NOCV-CD) approach, confirming the presence of a cis-halide → isocyanide direct interligand interaction...
November 15, 2018: Inorganic Chemistry
Eduardo Hernández-Vázquez, Alejandra Chávez-Riveros, Antonio Nieto-Camacho, Luis D Miranda
Inflammation is widely reported as a main factor for the development of chronic diseases such as cancer, diabetes and even metabolic syndrome. Thus, the search for novel anti-inflammatory compounds is required. Herein, we describe the synthesis of a collection of peptidic pyrazinones by a convenient approach which involved a multicomponent isocyanide-based reaction followed by a tandem deprotection/oxidative cyclization step. The series was tested for its potential anti-inflammatory capacity in an in vivo murine model, where 4 compounds were identified that inhibited tetradecanoylphorbol acetate-induced (TPA) edema more than 75%...
November 14, 2018: ChemMedChem
Girolamo Casella, Maurizio Casarin, Vadim Yu Kukushkin, Maxim L Kuznetsov
The mechanism of the addition of indazole (Ind)-a bifunctional aromatic N,NH-nucleophile-to cyclohexyl isocyanide coordinated to the palladium(II) center in the model complex cis -[PdCl₂(CNMe)(CNCy)] ( 1 ) to give the corresponding aminocarbene ligand was investigated in detail by theoretical (DFT) methods. The most plausible mechanism of this reaction is that of the associative type involving nucleophilic attack of Ind by its unprotonated N atom at the isocyanide carbon atom followed by the stepwise proton transfer from the nucleophile molecule to the isocyanide N atom via deprotonation/protonation steps...
November 10, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Liping Wang, Weikang Xiong, Yiyuan Peng, Qiuping Ding
A highly efficient Fe-catalyzed cascade addition/cyclization of 2-biphenyl isocyanides with toluenes for the synthesis of 6-benzylated phenanthridines has been reported. Di-tert-butyl peroxide (DTBP) was employed as both a radical initiator and an oxidant. The procedure tolerates various functional groups, providing the corresponding products in moderate to good yields. The proposed mechanism involves the cascade addition of benzyl radicals to the isocyanides and the following radical aromatic cyclization.
November 21, 2018: Organic & Biomolecular Chemistry
Xiaochen Du, Jianjun Huang, Anton A Nechaev, Ruwei Yao, Jing Gong, Erik V Van der Eycken, Olga P Pereshivko, Vsevolod A Peshkov
A series of propargylamides containing an electron-rich benzene ring was prepared through the Ugi reaction of 3,5-dimethoxyaniline with various propiolic acids, aldehydes and isocyanides. Subjecting these adducts to a gold-catalyzed intramolecular alkyne hydroarylation process allowed to efficiently construct the 2-quinolone core bearing a branched substituent on the nitrogen atom.
2018: Beilstein Journal of Organic Chemistry
Tomohiro Seki, Koh Kobayashi, Takaki Mashimo, Hajime Ito
Correction for 'A gold isocyanide complex with a pendant carboxy group: orthogonal molecular arrangements and hypsochromically shifted luminescent mechanochromism' by Tomohiro Seki et al., Chem. Commun., 2018, 54, 11136-11139.
November 20, 2018: Chemical Communications: Chem Comm
Wen-Kui Yuan, Yan Fang Liu, Zhenggang Lan, Li-Rong Wen, Ming Li
An efficient synthesis of thiazolidine-2,4,5-triimine derivatives was developed via Ni-catalyzed oxidative double isocyanide insertion to thioureas under air conditions, in which thioureas play three roles as a substrate, a ligand, and overcoming isocyanide polymerization. The reaction is featured by employing a low-cost and low loading Ni(acac)2 catalyst, without any additives, and high atom economy. This is the first example to directly apply a Ni(II) catalyst in oxidative double isocyanide insertion reactions...
November 16, 2018: Organic Letters
Michael J Wilhelm, George A Petersson, Jonathan M Smith, Drew Behrendt, Jianqiang Ma, Laura Letendre, Hai-Lung Dai
Photolysis of the diazine heterocycle, pyrazine, following irradiation at 308, 248, and 193 nm was examined using nanosecond time-resolved Fourier transform infrared emission spectroscopy. The resulting time-resolved IR emission spectra reveal that for 308 and 248 nm vibrationally highly excited pyrazine is produced, but no photolysis products were detected. However, at 193 nm excitation, the measured IR emission spectra consist solely of resonances originating from rovibrationally excited photofragments, including acetylene (HCCH), hydrogen cyanide (HCN), and hydrogen isocyanide (HNC), indicating that photofragmentation proceeds from vibrationally highly excited pyrazine on the ground electronic state...
November 21, 2018: Journal of Physical Chemistry. A
Jimil George, Seong-Yoon Kim, Kyungsoo Oh
A facile approach to spirocyclic pyrrolidinonylformimidamides has been developed via three-component reactions of isocyanides, alkenes, and amines. The reaction proceeds through a sequence of two distinct reaction pathways; the base-catalyzed conjugate addition of α-isocyano lactams to electron-deficient alkenes and the Ag(I)-catalyzed amine insertion to the isocyanide moiety. Both reactions display markedly different reaction kinetics, allowing the one-pot three-component reactions to be performed in the presence of respective catalysts, a Brønsted base and a silver salt...
November 16, 2018: Organic Letters
Onnicha Khaikate, Jatuporn Meesin, Manat Pohmakotr, Vichai Reutrakul, Pawaret Leowanawat, Darunee Soorukram, Chutima Kuhakarn
Diverse 2-sulfonyl- and 2-thiocyanato-3-substituted quinolines were synthesized from o-alkynylisocyanobenzenes by nucleophilic addition of the respective sulfinate sodium salts and ammonium thiocyanate to the isocyanide moiety followed by cyclization. The salient features of the methodology include metal-free, ambient temperature and mild reaction conditions, ease of reagent handling, and broad functional group tolerance.
November 14, 2018: Organic & Biomolecular Chemistry
Kristina Vlahoviček-Kahlina, Mario Vazdar, Andreja Jakas, Vilko Smrečki, Ivanka Jerić
We describe the utilization of bis-isopropylidene-protected d-fructose-derived aldehyde in the Passerini reaction with various acids and isocyanides. A library of densely functionalized glycomimetics bearing up to 3 carbohydrate units was obtained in high yields and diastereoselectivities. The configuration of the newly formed stereocenter was determined and the diastereoselectivity was rationalized by DFT calculations.
November 2, 2018: Journal of Organic Chemistry
Kin-Cheung Chan, Ka-Ming Tong, Shun-Cheung Cheng, Chi-On Ng, Shek-Man Yiu, Chi-Chiu Ko
Despite the well-reported MLCT [dπ(M) → π*(CNR)] transitions in the isocyano transition metal complexes, emissive complexes with phosphorescence derived from MLCT [dπ(M) → π*(CNR)] were not extensively studied. To provide insights into the design strategy of phosphorescent rhenium(I) complexes with an emissive 3 MLCT [dπ(Re) → π*(CNR)] excited state, a series of pentaisocyano rhenium(I) complexes have been synthesized. In contrast to most of the reported penta- or hexaisocyano rhenium(I) complexes with unsubstituted or alkyl- or monohalo-substituted phenylisocyanide ligands, which only exhibit photoluminescence in 77 K glassy medium, the solutions of all of these complexes were found to show phosphorescence at room temperature...
November 5, 2018: Inorganic Chemistry
Claire E Dickerson, Partha P Bera, Timothy J Lee
The structures and spectroscopic properties of azirine (C2 H3 N), a nitrogen-containing three-membered cyclic molecule, and its isomers were studied with state-of-the-art ab initio quantum chemical methods. Azirine is isomeric with methyl cyanide (CH3 CN) and methyl isocyanide (CH3 NC)-both observed in the star-forming regions of Sgr B2. In this study, we characterize the stationary points on the potential energy surface, relative energies, dipole moments, rotational constants, and harmonic vibrational frequencies of the 2 H-azirine ( a), 1 H-2,2 H-azirine ( b, carbene isomer), and 1 H-azirine ( c) cyclic isomers...
November 15, 2018: Journal of Physical Chemistry. A
Jian-Quan Liu, Xuanyu Shen, Yihan Wang, Xiang-Shan Wang, Xihe Bi
An unprecedented catalyst-dependent regioselective [3 + 2] cycloaddition of isocyanides with aryl diazonium salts is reported. 1,3-Disubstituted 1,2,4-triazoles were selectively obtained in high yield under Ag(I) catalysis, whereas 1,5-disubstituted 1,2,4-triazoles were formed by Cu(II) catalysis. These catalytic methodologies provide a controlled, modular, and facile access to 1,2,4-triazole scaffolds with high efficiency, broad substrate scope, and excellent functional group compatibility.
November 2, 2018: Organic Letters
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