18494-73-0Relevant articles and documents
Design and Syntheses of Palladium Complexes of NNN/CNN Pincer Ligands: Catalyst for Cross Dehydrogenative Coupling Reaction of Heteroarenes
Shinde, Vikki N.,Bhuvanesh, Nattamai,Kumar, Anil,Joshi, Hemant
, p. 324 - 333 (2020/02/04)
This report describes simple syntheses of a new class of palladium(II) pincer complexes having NNN and CNN coordination modes. The new complexes were fully characterized with the help of 1H and 13C{1H} NMR, HRMS, and IR sp
Oxime ester photoinitiators containing five-membered heteroaromatic ring structure, and preparation and use thereof
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Paragraph 0157-0162, (2019/12/25)
The invention relates to oxime ester compounds containing a five-membered heteroaromatic ring structure and represented by the formula (I) and (II), wherein m, n, n', A1, A2, R1, R2, R3, R4, R5, R6, R6'R7 and R7' are defined in the specification. The compounds represented by the formula (I) and (II) have excellent light absorption at 350-450 nm, can initiate the polymerization of acrylate monomersat low concentration, and have excellent thermal stability in the acrylate monomers, are oxime ester photoinitiators good in stability and suitable for a UV-Vis LED light source. The invention also relates to preparation of the compounds represented by the formula (I) and (II) and a use of the compounds represented by the formula (I) and (II) as photoinitiators or photosensitizers.
Halo-Bridged Abnormal NHC Palladium(II) Dimer for Catalytic Dehydrogenative Cross-Coupling Reactions of Heteroarenes
Sreejyothi,Sau, Samaresh Chandra,Vardhanapu, Pavan K.,Mandal, Swadhin K.
, p. 9403 - 9411 (2018/07/30)
This work describes the dehydrogenative coupling of heteroarenes using a dimeric halo-bridged palladium(II) catalyst bearing an abnormal NHC (aNHC) backbone. The catalyst can successfully activate the C-H bond of a wide range of heteroarenes, which include benzothiazole, benzoxazole, thiophene, furan, and N-methylbenzimidazole. Further, it exhibited good activity for heteroarenes bearing various functional groups such as CN, CHO, Me, OMe, OAc, and Cl. Additionally, we isolated the active catalyst by performing stoichiometric reaction and characterized it as the acetato-bridged dimer of (aNHC)PdOAc by single-crystal X-ray study.
Bis(dioxaborine) Dyes with Variable π-Bridges: Towards Two-Photon Absorbing Fluorophores with Very High Brightness
Marín, á. Moneo,Telo, Jo?o P.,Collado, Daniel,Nájera, Francisco,Pérez-Inestrosa, Ezequiel,Pischel, Uwe
supporting information, p. 2929 - 2935 (2018/02/09)
Bis(dioxaborine) dyes of the A-π-A format (A: acceptor, π: conjugated bridge) were prepared and photophysically characterized. The best performing dyes feature (a) visible-light absorption (>400 nm), (b) high molar absorption coefficients (up to 70000 m?1 cm?1), (c) Stokes shifts in the range of ca. 2500–5800 cm?1, and (d) strong fluorescence emission with quantum yields of up to 0.74. This yields very bright-emitting dyes for one-photon excitation. However, the most intriguing feature of the dyes is their strong two-photon absorption. This was achieved by means of increased π-conjugation in the phenylene or phenylene-thiophene bridges through the variation of the conjugation length and rigidity. This provided two-photon absorption cross sections of up to 2800 GM (1 Goeppert-Mayer (GM)=10?50 cm4 s photon?1). Considering the mentioned high fluorescence quantum yields, exceptionally bright-emitting A-π-A two-photon absorbing dyes with low molecular mass are obtained. Time-dependent density-functional theory calculations corroborated the experimental results.
Ex situ generation of stoichiometric HCN and its application in the Pd-catalysed cyanation of aryl bromides: Evidence for a transmetallation step between two oxidative addition Pd-complexes
Kristensen, Steffan K.,Eikeland, Espen Z.,Taarning, Esben,Lindhardt, Anders T.,Skrydstrup, Troels
, p. 8094 - 8105 (2017/11/27)
A protocol for the Pd-catalysed cyanation of aryl bromides using near stoichiometric and gaseous hydrogen cyanide is reported for the first time. A two-chamber reactor was adopted for the safe liberation of ex situ generated HCN in a closed environment, which proved highly efficient in the Ni-catalysed hydrocyanation as the test reaction. Subsequently, this setup was exploited for converting a range of aryl and heteroaryl bromides (28 examples) directly into the corresponding benzonitriles in high yields, without the need for cyanide salts. Cyanation was achieved employing the Pd(0) precatalyst, P(tBu)3-Pd-G3 and a weak base, potassium acetate, in a dioxane-water solvent mixture. The methodology was also suitable for the synthesis of 13C-labelled benzonitriles with ex situ generated 13C-hydrogen cyanide. Stoichiometric studies with the metal complexes were undertaken to delineate the mechanism for this catalytic transformation. Treatment of Pd(P(tBu)3)2 with H13CN in THF provided two Pd-hydride complexes, (P(tBu)3)2Pd(H)(13CN), and [(P(tBu)3)Pd(H)]2Pd(13CN)4, both of which were isolated and characterised by NMR spectroscopy and X-ray crystal structure analysis. When the same reaction was performed in a THF : water mixture in the presence of KOAc, only (P(tBu)3)2Pd(H)(13CN) was formed. Subjection of this cyano hydride metal complex with the oxidative addition complex (P(tBu)3)Pd(Ph)(Br) in a 1 : 1 ratio in THF led to a transmetallation step with the formation of (P(tBu)3)2Pd(H)(Br) and 13C-benzonitrile from a reductive elimination step. These experiments suggest the possibility of a catalytic cycle involving initially the formation of two Pd(ii)-species from the oxidative addition of LnPd(0) into HCN and an aryl bromide followed by a transmetallation step to LnPd(Ar)(CN) and LnPd(H)(Br), which both reductively eliminate, the latter in the presence of KOAc, to generate the benzonitrile and LnPd(0).
Amphiphilic viologen: Electrochemical generation of organic reductant and pd-catalyzed reductive coupling of aryl halides in water
Kuroboshi, Manabu,Yamamoto, Takashi,Tanaka, Hideo
, p. 197 - 200 (2013/03/14)
Electroreduction of 1,1′-bis(methoxyethoxyethoxyethyl)-4,4′- bipyridinium tosylate generated amphiphilic organic reductants, which promoted the Pd-catalyzed reductive coupling of aryl bromides in water to give the corresponding biaryls. The yields and selectivity of biaryls depended on the length of ethyleneoxy groups and substituents of the aryl bromides. Georg Thieme Verlag Stuttgart · New York.
Synthesis of functionalized 2-arylthiophenes with triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium catalysis
Rao, Maddali L. N.,Banerjee, Debasis,Dhanorkar, Ritesh J.
supporting information; experimental part, p. 1324 - 1330 (2011/07/07)
Atom-efficient cross-coupling reactions of functionalized 2-bromo- and 2-iodothiophenes have been demonstrated using triarylbismuths as atom-efficient multicoupling organometallic nucleophiles under palladium-catalyzed conditions. These couplings with various functionalized triarylbismuths proceeded smoothly to afford the corresponding functionalized 2-arylthiophenes in high yields. Georg Thieme Verlag Stuttgart · New York.
Synthesis and properties of terthiophene and bithiophene derivatives functionalized by BF2 chelation: A new type of electron acceptor based on quadrupolar structures
Ono, Katsuhiko,Nakashima, Akihiro,Tsuji, Yujiro,Kinoshita, Takatoshi,Tomura, Masaaki,Nishida, Jun-Ichi,Yamashita, Yoshiro
supporting information; experimental part, p. 13539 - 13546 (2011/02/24)
Terthiophene and bithiophene derivatives functionalized by BF2 chelation were synthesized as a new type of electron acceptor, and their properties were compared to those of bifuran and biphenyl derivatives. These new compounds are characterized
Efficient homo-coupling reactions of heterocyclic aromatic bromides catalyzed by Pd(OAc)2 using indium
Lee, Kooyeon,Lee, Phil Ho
, p. 4302 - 4305 (2008/09/21)
Homo-coupling reactions of heterocyclic aromatic bromides smoothly proceeded with cat-Pd(OAc)2, indium, and LiCl in DMF to afford exclusively symmetric biaryls possessing heterocyclic aromatic ring in good to excellent yields.
Palladium-catalysed direct C-H activation/arylation of heteroaromatics: An environmentally attractive access to bi- or polydentate ligands
Derridj, Fazia,Gottumukkala, Aditya L.,Djebbar, Safia,Doucet, Henri
experimental part, p. 2550 - 2559 (2009/03/11)
Bi- or polydentate ligands based on heterocycles can be easily prepared by palladium-catalysed C-H bond activation of heteroaromatics followed by heteroarylation with heteroaryl bromides. A variety of heteroaromatics such as furans, thiophenes, pyridines, thiazoles or oxazole derivatives have been employed and moderate to good yields were generally obtained using the air-stable complex [PdCl(dppb)(C3H5)] as catalyst. A range of functions such as acetyl, formyl, ester or nitrile on the heteroaromatics is tolerated. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
