89787-13-3Relevant articles and documents
Arylbiphenylene atropisomers: Structure, conformation, stereodynamics, and absolute configuration
Lunazzi, Lodovico,Mancinelli, Michele,Mazzanti, Andrea
, p. 2198 - 2205 (2008)
(Graph Presented) Anti and syn conformers, due to restricted sp 2-sp2 bond rotation, were detected in hindered 1,8-diarylbiphenylenes, the aryl moieties being phenyl groups bearing o-alkyl substituents such as Me, Et, i-Pr, and t-Bu.
An Improved PIII/PV=O-Catalyzed Reductive C-N Coupling of Nitroaromatics and Boronic Acids by Mechanistic Differentiation of Rate- And Product-Determining Steps
Li, Gen,Nykaza, Trevor V.,Cooper, Julian C.,Ramirez, Antonio,Luzung, Michael R.,Radosevich, Alexander T.
supporting information, p. 6786 - 6799 (2020/04/30)
Experimental, spectroscopic, and computational studies are reported that provide an evidence-based mechanistic description of an intermolecular reductive C-N coupling of nitroarenes and arylboronic acids catalyzed by a redox-active main-group catalyst (1,2,2,3,4,4-hexamethylphosphetane P-oxide, i.e., 1·[O]). The central observations include the following: (1) catalytic reduction of 1·[O] to PIII phosphetane 1 is kinetically fast under conditions of catalysis; (2) phosphetane 1 represents the catalytic resting state as observed by 31P NMR spectroscopy; (3) there are no long-lived nitroarene partial-reduction intermediates observable by 15N NMR spectroscopy; (4) the reaction is sensitive to solvent dielectric, performing best in moderately polar solvents (viz. cyclopentylmethyl ether); and (5) the reaction is largely insensitive with respect to common hydrosilane reductants. On the basis of the foregoing studies, new modified catalytic conditions are described that expand the reaction scope and provide for mild temperatures (T ≥ 60 °C), low catalyst loadings (≥2 mol%), and innocuous terminal reductants (polymethylhydrosiloxane). DFT calculations define a two-stage deoxygenation sequence for the reductive C-N coupling. The initial deoxygenation involves a rate-determining step that consists of a (3+1) cheletropic addition between the nitroarene substrate and phosphetane 1; energy decomposition techniques highlight the biphilic character of the phosphetane in this step. Although kinetically invisible, the second deoxygenation stage is implicated as the critical C-N product-forming event, in which a postulated oxazaphosphirane intermediate is diverted from arylnitrene dissociation toward heterolytic ring opening with the arylboronic acid; the resulting dipolar intermediate evolves by antiperiplanar 1,2-migration of the organoboron residue to nitrogen, resulting in displacement of 1·[O] and formation of the target C-N coupling product upon in situ hydrolysis. The method thus described constitutes a mechanistically well-defined and operationally robust main-group complement to the current workhorse transition-metal-based methods for catalytic intermolecular C-N coupling.
Rh(III)-Catalyzed C-H Activation of Boronic Acid with Aryl Azide
Xu, Shiyang,Huang, Baoliang,Qiao, Guanyu,Huang, Ziyue,Zhang, Zhen,Li, Zongyang,Wang, Peng,Zhang, Zhenhua
supporting information, p. 5578 - 5582 (2018/09/25)
A Rh(III)-catalyzed C-H activation of boronic acid with aryl azide to obtain unsymmetric carbazoles, 1H-indoles, or indolines has been developed. The reaction constructs dual distinct C-N bonds via sp2/sp3 C-H activation and rhodium nitrene insertion. Synthetically, this approach represents an access to widely used carbazole derivatives. The practical application to CBP and unsymmetric TCTA derivatives has also been performed. Mechanistic experiments and DFT calculations demonstrate that a five-membered rhodacycle species is the key intermediate.
LUMINESCENT DIAZABENZIMIDAZOLE CARBENE METAL COMPLEXES
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, (2015/02/25)
The present invention relates to metal-carbene complexes of the general formula (I), where variable M is Ir or Pt and that are characterized by variable R being a group of formula (a). The complexes are used in organic electronic devices, especially OLEDs (Organic Light-Emitting Diodes), illuminating elements, stationary visual display units and in material layers as emitter, charge transport material and/or charge or exiton blocker.
Cucurbit[8]uril recognition of rapidly interconverting diastereomers
Joseph, Roymon,Masson, Eric
, p. 632 - 641 (2015/10/19)
The diastereoselectivity of Cucurbit[8]uril (CB[8]) binding was probed towards a series of rapidly interconverting diastereomers containing a Caryl-Caryl chiral axis and at least one other stereocenter. Relative binding affinities of up to 4.9 were determined when CB[8] interacted with ortho, meta, ortho′-substituted biphenyls bearing a chiral dialkylsulfonium substituent at their meta-position. Diastereoselectivities of up to 2.4-fold were obtained for ortho′-substituted 2-phenylpyridinium derivatives that bear a chiral myrtenyl N-substituent prone to CB[8] binding.
Structure, conformation, and dynamic processes of the stereolabile atropisomers of hindered terphenyl hydrocarbons
Lunazzi, Lodovico,Mazzanti, Andrea,Minzoni, Mirko,Edgar Anderson
, p. 1291 - 1294 (2007/10/03)
(Chemical Equation Presented) Ortho-substituted p-terphenyl hydrocarbons exist as trans and cis atropisomers that were identified by low-temperature NMR spectroscopy. The interconversion barriers increase with the dimensions of the ortho substituents, the experimental values being matched by ab initio calculations. X-ray diffraction shows that only the trans atropisomer is present in the solids. Spectra of a tert-butyl derivative in nonequilibrium conditions indicate that the cis is more populated than the trans atropisomer in solution, favored by attractive interactions.
