CHIBACHA · Chiral Base C−H Activation
7РП — „Хора“ (Действия „Мария Кюри“)
- Период
- 2014-11-03 → 2016-11-02
- Финансиране от ЕС
- 269 744 €
- Участници
- 2
- Схема
- MC-IIF
Линиите свързват координатора с партньорите.
Накратко на български
Хиралното основание се изследва като средство за създаване на специфични молекули, като например хирални индолини. Този подход помага за по-ефективното и пестеливо изграждане на сложни функционални молекули от прости въглеводороди.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
Chiral Base C−H Activation
The transition-metal-catalyzed asymmetric C(sp3)−H activation is a powerful tool and an emerging research frontier for the atom-economical and step-economical construction of chiral functionalized molecules from simple hydrocarbon compounds. In this context, the oxidative addition-directed strategy was applied to asymmetric C(sp3)−H bond activation by using different catalytic systems composed of Pd0/base/chiral ligand. Mechanistically, C(sp3)−H bond cleavage in this approach has been shown to occur via a coordinated base-assisted concerted metalation-deprotonation mechanism. In the enantiodetermining step, not only the ligand, but also the base should be able to interact with the substrate via non-covalent bonding, and hence induce enantioselectivity. However, compared with the more studied Pd0/base/chiral ligand catalytic systems, no efficient enantioselective transformation catalyzed by Pd0/chiral base/achiral ligand systems has been reported before this project CHIBACHA. The EU-funded CHIBACHA (Chiral Base C−H Activation) project is an FP7-PEOPLE-2013 International Incoming Fellowship (IIF) Action. This work was carried out in UMR CNRS5246-ICBMS, University Claude Bernard Lyon 1 and the department of chemistry at University of Basel. The main purpose of this research project was to investigate the feasibility of the concept, i.e. asymmetric C(sp3)−H activation using a chiral base instead of a chiral ligand. Following the original plan described in the proposal, enantioselective synthesis of chiral indolines was first selected as a benchmark reaction to test the feasibility of our concept. Through an extensive optimization study, it was found that high levels of enantioselectivity (up to 98:2 e.r.) and efficiency (up to 96% yield) can be obtained for a variety of indoline products containing both tri- and tetrasubstituted stereocenters using a chiral catalytic base, which is formed in situ upon deprotonation of a chiral phosphoric acid, as the sole source of chirality. Given that the chiral base C−H activation concept was successfully realized, we continued to extend this approach to the construction of valuable chiral six-membered nitrogen cycles (up to 95:5 e.r.) and four-membered carbon cycles with a promising e.r. (68:32). As we expected in the proposal, this project thus opened a very important field in asymmetric C(sp3)−H activation and will allow more researchers to work in this area. We are confident that more interesting results related to chiral base C−H activation will be disclosed and reported in the near future.
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
The goal of this proposal is to develop a new strategy for asymmetric C(sp3)−H activation using a chiral base instead of chiral ligand, and will focus on oxidative addition-induced and decarboxylation-induced reactions. Using this new strategy, a wide range of representative and valuable chiral four-membered (hetero)cyclic and five-membered (hetero)cyclic organic molecules will be synthesized.Typical chiral Br¢nsted acids and the designed ionic liquid-functionalized chiral phosphoric acids will be prepared by using commercially available raw materials. They will be tested in the two proposed concepts. In the case of oxidative addition-induced reactions, some feasible examples aiming at synthesizing chiral indanes, indolines, dihydrobenzofurans, benzocyclobutenes, and lactams will be developed from readily available aryl or alkenyl halides or triflates. For the decarboxylation-induced reactions, a racemic version will be first developed. Then, the chiral base concept will be applied in the synthesis of chiral benzocyclobutenes, indanes, indolines, and dihydrobenzofurans. In each of the reactions involved, some key reaction parameters including chiral acid, ligand, solvent, base, reaction temperature as well as the structural features of the substrates will be studied. In addition, recyclable ionic liquid-functionalized chiral Br¢nsted acids and the effect of traditional ionic liquids as the additives or solvents will be first studied in enantioselective C(sp3)−H bond activation. In order to get a clear understanding on the nature of the asymmetric induction during the catalytic cycle, computational studies will also be performed using DFT methods.The applicant's previous research experience in C−H activation, ionic liquids catalysis and asymmetric catalysis areas will benefit the project. The project will foster mutually beneficial research collaboration in Europe in the field of C−H activation and green chemistry.
Оригинален текст от CORDIS (на английски).
Участници
Връзки
Данни: CORDIS, © Европейски съюз