769-26-6Relevant articles and documents
The impact of cation structure upon the acidity of triazolium salts in dimethyl sulfoxide
Konstandaras, Nicholas,Dunn, Michelle H.,Guerry, Max S.,Barnett, Christopher D.,Cole, Marcus L.,Harper, Jason B.
supporting information, p. 66 - 75 (2019/12/26)
A series of triazolium salts, selected for their varying electronic and steric properties, were prepared and their pKa values were determined in DMSO at 25 °C using the bracketing indicator method. The effect of each systematic structural variation upon the acidity of the triazolium cation has been considered, in particular examining the effects of systematically altering electronic properties, quantified through the use of Hammett σ parameters. The first pKa value for an azolium salt that generates a mesionic carbene is also reported. These new data allow for the selection of appropriate bases for the deprotonation of such triazolium salts and the potential to correlate the pKa values determined herein with the nucleophilicity of the corresponding carbenes.
Gold-Catalyzed Regiospecific Annulation of Unsymmetrically Substituted 1,5-Diynes for the Precise Synthesis of Bispentalenes
Tavakkolifard, Sara,Sekine, Kohei,Reichert, Lisa,Ebrahimi, Mina,Museridz, Ketevan,Michel, Elena,Rominger, Frank,Babaahmadi, Rasool,Ariafard, Alireza,Yates, Brian F.,Rudolph, Matthias,Hashmi, A. Stephen K.
supporting information, p. 12180 - 12186 (2019/09/06)
Precise control of the selectivity in organic synthesis is important to access the desired molecules. We demonstrate a regiospecific annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene derivatives for a geometry-controlled synthesis of linear bispentalenes, which is one of the promising structures for material science. A gold-catalyzed annulation of unsymmetrically substituted 1,2-di(arylethynyl)benzene could produce two isomeric pentalenes, but both electronic and steric effects on the aromatics at the terminal position of the alkyne prove to be crucial for the selectivity; especially a regiospecific annulation was achieved with sterically blocked substituents; namely, 2,4,6-trimetyl benzene or 2,4-dimethyl benzene. This approach enables the geometrically controlled synthesis of linear bispentalenes from 1,2,4,5-tetraethynylbenzene or 2,3,6,7-tetraethynylnaphthalene. Moreover, the annulation of a series of tetraynes with a different substitution pattern regioselectively provided the bispentalene scaffolds. A computational study revealed that this is the result of a kinetic control induced by the bulky NHC ligands.
Gold-Catalyzed Hydrohydrazidation of Terminal Alkynes
Zimin, Dmitry P.,Dar'In, Dmitry V.,Rassadin, Valentin A.,Kukushkin, Vadim Yu.
supporting information, p. 4880 - 4884 (2018/08/24)
Facile gold-catalyzed hydrohydrazidation of alkynes with various hydrazides R2CONHNH2 (R = Alk or Ar; including those with an additional nucleophilic moiety) in the presence of Ph3PAuNTf2 (6 mol %) leading to a wide range of substituted keto-N-acylhydrazones (18 examples) in excellent to good yields (99-66%) is reported. This novel metal-catalyzed coupling proceeds under mild conditions (chlorobenzene, 60 °C), exhibits high functional group tolerance, and is insensitive to the electronic and steric effects of the substituents in the reactants.
Regio- and stereoselective dimerization of arylacetylenes and optical and electrochemical studies of (E)-1,3-enynes
Morozov, Oleg S.,Asachenko, Andrey F.,Antonov, Denis V.,Kochurov, Vitaly S.,Paraschuk, Dmitry Yu.,Nechaev, Mikhail S.
supporting information, p. 2671 - 2678 (2014/09/29)
The N-heterocyclic carbene palladium complex (SIPr)Pd(cinnamyl)Cl [SIPr=N,N'-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) promotes regio- and stereospecific dimerization of a variety of arylalkynes to give (E)-1,3-enynes in good to excellent yields. An efficient and practical procedure for their synthesis was developed using a biphasic aqueous alkali/heptane system. Optical and electronic properties of (E)-1,3-enynes are highly tunable. Depending on the nature of the substituents, HOMO energies vary in the range 5.3-6.0eV. (E)-1,3-Enynes can exhibit intense photoluminescence in the spectral region 350-500nm.
Palladium nanoparticles catalyzed Sonogashira reactions for the one-pot synthesis of symmetrical and unsymmetrical diarylacetylenes
Mandali, Pavan Kumar,Chand, Dillip Kumar
, p. 40 - 44 (2014/02/14)
A variety of symmetrical and unsymmetrical diarylacetylenes are synthesized by ligand-free palladium nanoparticles catalyzed copper-free and amine-free Sonogashira cross-coupling reactions between aryl iodides and trimethylsilylacetylene (TMSA) under mild reaction conditions.
Synthesis and reactivity of aryl(alkynyl)iodonium salts
Dixon, Luke I.,Carroll, Michael A.,Gregson, Thomas J.,Ellames, George J.,Harrington, Ross W.,Clegg, William
, p. 2334 - 2345 (2013/05/21)
The first practical, yet simple, preparation of aryl(alkynyl)iodonium trifluoroacetate salts is described. The generic nature of this synthetic method has allowed the production of a range of aryl(alkynyl)iodonium trifluoroacetate salts with independent variation of both the alkynyl and aryliodo groups in yields of 30-85 %. Application of these new reagents to the synthesis of a series of 2-arylfuro[3,2-c]pyridines (40-64 %) highlights the potential of this class of materials as precursors to bioactive heterocyclic structures. These experiments have also demonstrated that, in this case, the effect of the aryliodo group on the reaction is negligible.
Efficient approach to 1,2-diazepines via formal diazomethylene insertion into the C-C bond of cyclobutenones
Sugimoto, Kenji,Hayashi, Rie,Nemoto, Hideo,Toyooka, Naoki,Matsuya, Yuji
supporting information; experimental part, p. 3510 - 3513 (2012/07/31)
Efficient monocyclic 1,2-diazepine formation via a tandem electrocyclization reaction of cyclobutenones with lithiodiazoacetate is demonstrated. The reaction proceeds through an oxy anion-accelerated 4π-ring opening of cyclobutene followed by an 8π-ring closure of the resultant oxy anion-substituted diazo-diene under mild conditions to furnish a 1,2-diazepine via formal diazomethylene insertion into the C-C bond of cyclobutenone.
Metal-free 1,5-regioselective azide-alkyne [3+2]-cycloaddition
Kloss, Florian,Koehn, Uwe,Jahn, Burkhard O.,Hager, Martin D.,Goerls, Helmar,Schubert, Ulrich S.
, p. 2816 - 2824 (2012/06/01)
[3+2]-cycloaddition reactions of aromatic azides and silylated alkynes in aqueous media yield 1,5-disubstituted-4-(trimethyl-silyl)-1H-1,2,3-triazoles. The formation of the 1,5-isomer is highly favored in this metal-free cycloaddition, which could be proven by 1D selective NOESY and X-ray investigations. Additionally, DFT calculations corroborate the outstanding favoritism regarding the 1,5-isomer. The described method provides a simple alternative protocol to metal-catalyzed "click chemistry" procedures, widening the scope for regioselective heavy-metal-free synthetic applications.
Aromatic stabilization of the triarylborirene ring system by tricoordinate boron and facile ring opening with tetracoordinate boron
Eisch, John J.,Shafii, Babak,Odom, Jerome D.,Rheingold, Arnold L.
, p. 1847 - 1853 (2007/10/02)
To remove uncertainties in the apparent C=C and B-C bond lengths of the borirene ring, as previously estimated from an X-ray crystallographic analysis of trimesitylborirene, the unsymmetrically substituted 2-(2,6-dimethylphenyl)-1,3-dimesitylborirene was
