1165-57-7Relevant academic research and scientific papers
Acid-catalyzed rearrangements in arenes: Interconversions in the quaterphenyl series
Skraba-Joiner, Sarah L.,Holt, Carter J.,Johnson, Richard P.
, p. 2655 - 2663 (2019)
Arenes undergo rearrangement of phenyl, alkyl, halogen and other groups through the intermediacy of ipso arenium ions in which a proton is attached at the same carbon as the migrating substituent. Interconversions among the six quaterphenyl isomers have b
Fine Tuning of Chiral Bis(N-heterocyclic carbene) Palladium Catalysts for Asymmetric Suzuki-Miyaura Cross-Coupling Reactions: Exploring the Ligand Modification
Zhang, Dao,Yu, Jueqin
, p. 1269 - 1280 (2020/05/05)
Novel chiral N,N′-bisaryl bis(NHC) ligand precursors H2[(S)-2]Cl2 on a spiro scaffold and H2[(S)-3b-g]Cl2 with a binaphthyl linkage were rationally designed and their cyclometalated cis-chelated NHC palladium complexes (S)-5, (S)-6, and (S)-7b-g have been synthesized and fully characterized. Complexes 6 and 7b were further confirmed by X-ray single-crystal analysis. Both complexes adopted a slightly distorted square planar geometry around the Pd(II) center. The structure of 6 consists of a rare dimeric arrangement incorporating two palladium(II) centers bonded through a short metal-metal bond (2.853(2) ?), indicating a PdII-PdII intramolecular interaction (?). These N,N′-bisaryl-bis(NHC)-Pd complexes together with N,N′-bisalkyl analogues {[(S)-1a-d]PdX2} (X = I, (S)-4a; X = Br, (S)-4b-d) have been used in the asymmetric aryl-aryl cross-coupling reactions of arylboronic acids and aryl halides. The enantioselectivity of the biaryl products was greatly improved within 24 h (up to 74% ee) when complexes 7a-g were used as catalysts. The results show that for these types of bis(NHC) palladium catalysts the structural characters of the chiral scaffolds play a decisive role in the enantioselectivities of cross-coupling reactions.
Syntheses and Spectral Characteristics of Seven Polyphenyls Containing Highly Branched para-Phenylene Ring(s)
Fujioka, Yasuhiro,Ozasa, Shigeru,Sato, Kazumi,Ibuki, Eiichi
, p. 22 - 29 (2007/10/02)
Seven polyphenyls, including four new compounds, 2,2',6'- (2) and 3,2',6'-triphenyl-p-terphenyl (3), 3',5'-diphenyl-p-quarterphenyl (4), and 2-phenyl-3'-(2-biphenylyl)-p-terphenyl (7), were synthesized by the Ullmann coupling reaction of aryl iodide(s) or by the Kharash type coupling reaction of aryl Grignard reagent with an aryl iodide catalyzed by bis(acetylacetonato)-nickel(II).Infrared spectral studies of the polyphenyls showed that the range of 730-770 cm-1, generally accepted as the position of the out-of-plane C-H bending bands of the phenyl ring, should be widened slightly to 730-786 cm-1.The high frequency bands were confirmed to be correlated closely to the overcrowding by terminal rings in the complex structures.Proton magnetic resonance spectral studies indicated that he characteristic spectral features of the branched polyphenyls were consistent with their conformational aspects deduced from stereomodels.In the ultraviolet spetcral studies the polyphenyls containing highly branched p-phenylene ring(s) showed intense K-bands or shoulders at locations very similar to those of the corresponding linear polyphenyls containing the same number of p-phenylene rings. Keywords -- Ullmannn reaction; Ni-complex-catalyzed cross-coupling; quinquephenyl; sexiphenyl; octiphenyl; IR; UV; 1H-NMR
Syntheses and Spectral Properties of Several Branched-chain Polyphenyls containing 1,3,5-Trisubstituted Ring(s)
Ozasa, Shigeru,Fujioka, Yasuhiro,Hashino, Hiromi,Kimura, Naoko,Ibuki, Eiichi
, p. 2313 - 2320 (2007/10/02)
Six polyphenyls, including four new compounds, 5',5''-di(2-biphenylyl)-2,2'''-diphenyl-m-quaterphenyl (3), 2,5',2''-triphenyl-m-terphenyl (4), 3,5-di(2-biphenylyl)-o-terphenyl (5), and 5''-(3-biphenylyl)-m-quinquephenyl (6), were synthesized by the Ullmann coupling reaction of iodo compounds.Proton magnetic resonance spectral studies indicated that the characteristic spectral features of the polyphenyls containing 1,3,5-trisubstituted ring system(s) were fully compatible with their conformational aspects deduced from stereomodels.Ultraviolet spectral data indicated that the dihedral angle of the pivot bond of the branched ring in the polyphenyls in solution is very similar to that of biphenyl.Keywords - Ullmann reaction; quinquephenyl; sexiphenyl; septiphenyl; decaphenyl; polyphenyl; IR; UV; 1H-NMR
Syntheses and Physical Properties of Several Octiphenyls and a Septiphenyl
Ozasa, Shigeru,Fujioka, Yasuhiro,Fujiwara, Michiko,Ibuki, Eiichi
, p. 3210 - 3222 (2007/10/02)
Six symmetrical linear octiphenyls were synthesized by the Ullmann homo-coupling reaction of iodoquaterphenyl.Another satisfactory method for synthesizing octiphenyls is also described, i.e., a Kharash-type Grignard cross-coupling of biphenylylmagnesium bromide and diiodoquaterphenyl in the presence of bis(acetylacetonato)nickel(II).Moreover, m-septiphenyl was succesfully synthesized by deamination of the corresponding amino compound.Infrared studies of the polyphenyls indicated that the fine-structure bands in the regions of 770-810 and 870-915 cm-1 may be considered as indicators of the presence of consecutive m-phenylene rings, regardless of the existence of o- or p-phenylene rings.The ultraviolet spectra of the octiphenyls, which contain two kinds of linkages, showed absorption curves closely related to those of quaterphenyls corresponding to the structural units of the former compounds.The nuclear magnetic resonance spectra of the polyphenyls without an o-phenylene ring showed multiplet peaks due to the resonances of an isolated m-phenylene proton at the lowest field within a narrow region (δ 7.81-7.95).Hueckel molecular orbital calculations of the longest wavelength absorption bands of ten polyphenyls were carried out.The calculated and observed wavelengths were in rather good agreement except for the cases of three compounds.Keywords - Ullmann reaction; Ni-complex-catalyzed cross-coupling; octiphenyls; septiphenyls; IR; UV; NMR; MO; quaterphenyl derivatives; polyphenyls
