58966-29-3Relevant articles and documents
Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation
Fanourakis, Alexander,Paterson, Kieran J.,Phipps, Robert J.,Williams, Benjamin D.
supporting information, p. 10070 - 10076 (2021/07/21)
The enantioselective amination of C(sp3)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh2(esp)2, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C-H amination of substrates bearing pendant hydroxyl groups. Additionally, the quinoline of the chiral cation appears to engage in axial ligation to the rhodium complex, providing improved yields of product versus Rh2(esp)2 and highlighting the dual role that the cation is playing. These results underline the potential of using chiral cations to control enantioselectivity in challenging transition-metal-catalyzed transformations.
Amine compound and a manufacturing method thereof, and use thereof
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Paragraph 0082, (2020/07/01)
PROBLEM TO BE SOLVED: To provide a material for an organic EL developing a higher efficiency than conventional materials, and a material very useful particularly in an organic EL device using a phosphorescent material. SOLUTION: The material is an a
SELECTIVITY AND MECHANISM IN THE SIDE-CHAIN HALOGENATION OF METHYLBENZENES PROMOTED PHOTOCHEMICALLY AND BY METAL COMPLEXES IN THE PRESENCE OF HALIDE IONS
Baciocchi, Enrico,Crescenzi, Manuela
, p. 6525 - 6536 (2007/10/02)
The intramolecular selectivity in a variety of side-chain halogenations of alkyl-aromatics has been determined in AcOH by measuring the isomeric distribution in the reactions of 4-t-butyl- and 4-chloro-1,2-dimethylbenzene (1 and 2, respectively) with: Br2/hν, CAN/Br-, CAN=cerium(IV) ammonium nitrate, cobalt(III) acetate/Br-, S2O8=/Br-, N-bromosuccinimide (in CCl4), Cl2/hν, CAN/Cl-, cobalt(III) acetate/Cl-.In the bromination reactions selectivity is independent of the reaction conditions, thus suggesting that in all brominating systems Br. is the actual reacting species.Very surprisingly, with 1 as the substrate, Cl2/hν is a more selective system than Br2/hν.With 2 the two systems display similar selectivity.It has been suggested that in AcOH the transition state for photochlorination has an electron transfer character which increases as the substrate becomes more electron rich.The idea of a "variable" transition state for the photochlorination in AcOH is supported by data of relative reactivity of substituted toluenes indicating that the effect on the rate increases as the substituent becomes more electron donor.AcOH must have an essential role in this respect since in CCl4 situation returns to be "normal" with chlorination less selective than bromination.Selectivity of CAN/Cl- is very similar to that of Cl2/hν, whereas significant differences are observed with cobalt(III) acetate/Cl-.Probably Cl. and a cobalt(III) chloride complex are the reacting species in CAN/Cl- and cobalt(III) acetate/Cl-, respectively.