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Thesis

Chiral Cyclopentadienyl Ruthenium (II) Complexes: Synthesis and Applications in Catalysis

Cyclopentadienyl ruthenium(II) complexes are an important class of homogenous catalysts. They engage in a multitude of different transformations, for example cycloisomerizations. Due to a lack of suitable chiral cyclopentadienyl ligands, no efficient enantioselective version of the cationic CpRu(MeCN)3PF6 catalyst had been developed in the past, despite synthetic needs and potential. This thesis describes a general synthesis of efficient chiral CpxRu(II) catalysts. An atropchiral C2-symmetric biaryl ligand scaffold proved to be the most suitable and allows for fine-tuning of the corresponding complexes. The synthesis of the best performing ligand has been reduced to six steps form (R)-BINOL by implementing a C–H activation strategy. The cationic catalyst I enabled the highly enantioselective cyclization of yne-enone II to 4H-pyrans III. A tremendous counterion effect on the reaction outcome was observed. In situ formation of neutral CpxRu(II) species IV gave rise to a complementary set of catalysts, competent for an enantioselective formal [2+2] reaction of strained alkenes V and internal alkynes VI. Cyclobutenes VII were rapidly formed under mild conditions. Both propiolates and alkynyltriazenes were suitable substrates, enabling rich follow-up chemistry via derivatization of the products

    Keywords: ruthenium ; cyclopentadienyl ligand ; asymmetric catalysis ; cycloisomerization

    Thèse École polytechnique fédérale de Lausanne EPFL, n° 7744 (2017)
    Programme doctoral Chimie et Génie chimique
    Faculté des sciences de base
    Institut des sciences et ingénierie chimiques
    Laboratoire de catalyse et synthèse asymétriques
    Jury: Prof. Jieping Zhu (président) ; Prof. Nicolai Cramer (directeur de thèse) ; Prof. Jérôme Waser, Prof. Lutz Ackermann, Prof. Corinna Schindler (rapporteurs)

    Public defense: 2017-5-30

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    Record created on 2017-05-24, modified on 2017-09-05

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