1206-76-4Relevant academic research and scientific papers
Magnesium and calcium complexes containing biphenyl-based tridentate iminophenolate ligands for ring-opening polymerization of rac -lactide
Yi, Wei,Ma, Haiyan
, p. 11821 - 11835 (2013)
A series of racemic 2-[(2′-methoxybiphenyl-2-ylimino)methyl]-4-R 2-6-R1-phenols (L1H-L8H) were reacted with {Mg[N(SiMe3)2]2}2 and Ca[N(SiMe3)2]2·2THF (THF = tetrahydrofuran), respectively, to provide nine heteroleptic magnesium complexes L1-8MgN(SiMe3)2 [R1 = iPr, R2 = H (1a); R1 = tBu, R 2 = Me (2a and 2a·THF); R1 = R2 = tBu (3a); R1 = R2 = CMe2Ph (4a); R1 = CPh3, R2 = tBu (5a); R 1 = 1-piperidinylmethyl, R2 = tBu (6a); R 1 = Cl, R2 = tBu (7a); R1 = Br, R2 = tBu (8a)], two homoleptic calcium complexes (L 2,5)2Ca (2b and 5b), and one heteroleptic calcium complex [(L4)CaN(SiMe3)2·THF] (4b), which have been fully characterized. In the solid state, magnesium complexes 2a and 6a are isostructural, and each possesses a monomeric structure, while magnesium complexes 7a and 8a are dimeric, where the two metal centers are bridged by two phenolate oxygen atoms of the ligands. The coordination geometry around the magnesium center in these complexes can be best described as a distorted tetrahedral geometry. Although bearing the same iminophenoloate ligand, the molecular structures of complexes 2a and 2a·THF are different from each other. In complex 2a·THF, the coordination of one molecule of THF to the magnesium atom leads to dissociation of the methoxy group of the ligand from the metal center. The homoleptic calcium complex 2b has a six-coordinate metal core ligated by all six donor atoms of two iminophenolate ligands. The heteroleptic magnesium complexes 1a-8a and calcium complex 4b proved to be efficient initiators for the ring-opening polymerization of rac-lactide at ambient temperature in THF or at 70 C in toluene, and the polymerizations were better controlled in the presence of 2-propanol. The introduction of a bulky ortho substituent on the phenoxy unit of the ligand resulted in an increase of the catalytic activity of the corresponding metal complex. Microstructure analysis of the resultant poly(rac-lactide) samples via homonuclear-decoupled 1H NMR spectroscopy revealed Pr values ranging from 0.60 to 0.81, which closely depended on the employed catalyst and polymerization conditions.
Synthesis of 3-aryl-1-phosphinoimidazo[1,5-a]pyridine ligands for use in Suzuki-Miyaura cross-coupling reactions
Dinh, Long P.,Harris, Nekoda W.,Jacoby, Seth A.,Semsey, Rebecca Y.,Swann, William A.,Tran, Ryan Q.,Williamson, Savannah N.,Yet, Larry
, p. 28347 - 28351 (2021/09/15)
3-Aryl-1-phosphinoimidazo[1,5-a]pyridine ligands were synthesized from 2-aminomethylpyridine as the initial substrateviatwo complementary routes. The first synthetic pathway underwent the coupling of 2-aminomethylpyridine with substituted benzoyl chlorides, followed by cyclization, iodination and palladium-catalyzed cross-coupling phosphination reactions sequence to give our phosphorus ligands. In the second route, 2-aminomethylpyridine was cyclized with aryl aldehydes, followed by the iodination and palladium-catalyzed cross-coupling phosphination reactions to yield our phosphorus ligands. The 3-aryl-1-phosphinoimidazo[1,5-a]pyridine ligands were evaluated in palladium-catalyzed sterically-hindered biaryl and heterobiaryl Suzuki-Miyaura cross-coupling reactions.
Scalable electrochemical synthesis of diaryliodonium salts
Elsherbini, Mohamed,Moran, Wesley J.
supporting information, p. 4706 - 4711 (2021/06/11)
Cyclic and acyclic diaryliodonium are synthesised by anodic oxidation of iodobiaryls and iodoarene/arene mixtures, respectively, in a simple undivided electrolysis cell in MeCN-HFIP-TfOH without any added electrolyte salts. This atom efficient process does not require chemical oxidants and generates no chemical waste. More than 30 cyclic and acyclic diaryliodonium salts with different substitution patterns were prepared in very good to excellent yields. The reaction was scaled-up to 10 mmol scale giving more than four grams of dibenzo[b,d]iodol-5-ium trifluoromethanesulfonate (>95%) in less than three hours. The solvent mixture of the large-scale experiment was recovered (>97%) and recycled several times without significant reduction in yield.
Atmosphere-Controlled Palladium-Catalyzed Divergent Decarboxylative Cyclization of 2-Iodobiphenyls and α-Oxocarboxylic Acids
Zhou, Liwei,Sun, Mingjie,Zhou, Fengru,Deng, Guobo,Yang, Yuan,Liang, Yun
supporting information, p. 7150 - 7155 (2021/09/18)
A novel palladium-catalyzed divergent decarboxylative cyclization of 2-iodobiphenyls and α-oxocarboxylic acids utilizing the atmosphere as a controlled switch is reported. Under the protection of a nitrogen atmosphere, tribenzotropones are synthesized by a [4 + 3] decarboxylative cyclization. Employing a palladium/O2 system enables a [4 + 2] decarboxylative cyclization to assemble triphenylenes. Notably, preliminary mechanistic studies indicate that the formation of triphenylenes involves a double decarboxylation.
Photocatalytic xanthate-based radical addition/cyclization reaction sequence toward 2-biphenyl isocyanides: Synthesis of 6-alkylated phenanthridines
López-Mendoza, Pedro,Miranda, Luis D.
supporting information, p. 3487 - 3491 (2020/05/25)
A photocatalytic xanthate-based radical addition/cyclization reaction cascade toward 2-biphenylisocyanides is described as a practical and modular approach to 6-alkylated phenanthridines. The use of xanthates as radical precursors allowed the synthesis of diversely 6-substituted phenanthridines. Electrophilic radicals derived from nitriles, aromatic and aliphatic ketones, malonates, and amide derivatives, as well as radicals derived from phthalimidomethyl and benzylic derivatives were successfully introduced. The reaction proceeds under mild conditions without a stoichiometric amount of oxidant. Thirty novel phenanthridine scaffolds were synthesized with yields ranging from 24 to 76%.
HETEROCYCLIC COMPOUND AND ORGANIC LIGHT EMITTING DEVICE COMPRISING SAME
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Paragraph 0224-0226, (2020/05/14)
The present specification relates to a heterocyclic compound represented by Chemical Formula 1, and an organic light emitting device comprising the same.
Visible-Light-Driven Difluoromethylation of Isocyanides with S-(Difluoromethyl)diarylsulfonium Salt: Access to a Wide Variety of Difluoromethylated Phenanthridines and Isoquinolines
Chen, Jia-Yi,Li, Xin,Lin, Li-Ting,Liu, Guo-Kai,Qin, Wen-Bing,Wong, Henry N. C.,Xiong, Wei
, p. 10479 - 10487 (2020/09/23)
A highly efficient approach of visible-light-driven radical difluoromethylation of isocyanides to access a wide variety of difluoromethylated phenanthridines and isoquinolines is herein described. Electrophilic S-(difluoromethyl)diarylsulfonium salt proved to be a good difluoromethyl radical precursor under photoredox catalysis. A broad range of isocyanides were tolerated to furnish the corresponding difluoromethylated phenanthridines, isoquinolines, furo[3,2-c]pyridine, and pyrido[3,4-b]indole in moderate to excellent yields under mild conditions. A plausible mechanism was also proposed.
Polyfunctional Imidazolium Aryloxide Betaine/Lewis Acid Catalysts as Tools for the Asymmetric Synthesis of Disfavored Diastereomers
Willig, Felix,Lang, Johannes,Hans, Andreas C.,Ringenberg, Mark R.,Pfeffer, Daniel,Frey, Wolfgang,Peters, René
supporting information, p. 12029 - 12043 (2019/08/16)
Enzymes are Nature's polyfunctional catalysts tailor-made for specific biochemical synthetic transformations, which often proceed with almost perfect stereocontrol. From a synthetic point of view, artificial catalysts usually offer the advantage of much broader substrate scopes, but stereocontrol is often inferior to that possible with natural enzymes. A particularly difficult synthetic task in asymmetric catalysis is to overwrite a pronounced preference for the formation of an inherently favored diastereomer; this requires a high level of stereocontrol. In this Article, the development of a novel artificial polyfunctional catalyst type is described, in which an imidazolium-aryloxide betaine moiety cooperates with a Lewis acidic metal center (here Cu(II)) within a chiral catalyst framework. This strategy permits for the first time a general, highly enantioselective access to the otherwise rare diastereomer in the direct 1,4-addition of various 1,3-dicarbonyl substrates to β-substituted nitroolefins. The unique stereocontrol by the polyfunctional catalyst system is also demonstrated with the highly stereoselective formation of a third contiguous stereocenter making use of a diastereoselective nitronate protonation employing α,β-disubstituted nitroolefin substrates. Asymmetric 1,4-additions of β-ketoesters to α,β-disubstituted nitroolefins have never been reported before in literature. Combined mechanistic investigations including detailed spectroscopic and density functional theory (DFT) studies suggest that the aryloxide acts as a base to form a Cu(II)-bound enolate, whereas the nitroolefin is activated by H-bonds to the imidazolium unit and the phenolic OH generated during the proton transfer. Detailed kinetic analyses (RPKA, VTNA) suggest that (a) the catalyst is stable during the catalytic reaction, (b) not inhibited by product and (c) the rate-limiting step is most likely the C-C bond formation in agreement with the DFT calculations of the catalytic cycle. The robust catalyst is readily synthesized and recyclable and could also be applied to a cascade cyclization.
Correction to: Polyfunctional Imidazolium Aryloxide Betaine/Lewis Acid Catalysts as Tools for the Asymmetric Synthesis of Disfavored Diastereomers (Journal of the American Chemical Society (2019) 141 (12029-12043) DOI: 10.1021/jacs.9b04902)
Willig, Felix,Lang, Johannes,Hans, Andreas C.,Ringenberg, Mark R.,Pfeffer, Daniel,Frey, Wolfgang,Peters, René
supporting information, p. 17022 - 17022 (2019/11/14)
Page 12035 and Supporting Information pp S91-S94. It has come to our attention that the wrong initial concentration of 1a was erroneously used in two experiments of the "same excess" protocol.1 The experiments were thus repeated (0.055 rather than 0.06 mol/L of 1a was erroneously used before), and an excellent overlay of the "time-adjusted same excess" reaction profiles and the standard reaction profile, as previously presented, was found. This indicates that no significant catalyst deactivation takes place and that the active catalyst concentration remains constant during the catalytic reaction. The conclusions are thus not affected by the unintentional error. The corrected Figure 1 is shown below, and a corrected including Figures S1-S28 and Tables S1-S8 (corrected).(Figure Persented).Supporting Information file is available, in which pp S91?S94 have been replaced, in which the correct kinetic experiments are described, including raw data. We apologize for any inconvenience.
NBE-Controlled Palladium-Catalyzed Interannular Selective C-H Silylation: Access to Divergent Silicon-Containing 1,1′-Biaryl-2-Acetamides
Li, Wenguang,Chen, Wenqi,Zhou, Bang,Xu, Yankun,Deng, Guobo,Liang, Yun,Yang, Yuan
supporting information, p. 2718 - 2722 (2019/04/16)
A novel palladium-catalyzed interannular selective C-H silylation of 1,1′-biaryl-2-acetamides is described. The combination of palladium catalyst with copper oxidant enables meta- or ortho-selective C-H silylation by employing hexamethyldisilane as a trimethylsilyl source, which relies on the control of NBE derivatives as a switch, thus providing straightforward access to divergent silicon-containing 1,1′-biaryl-2-acetamides.
