creator: Houri, Ahmad Farouk
description- – Chapter I. The chemistry and catalytic activity of $/rm Cp/sb2ZrCl/sb2$ is reviewed, particularly in connection with its interaction with Grignard reagents. The most recent advances in carbon-carbon bond formation by the addition of alkyl magnesium halide reagents to olefins in the presence of $/rm Cp/sb2ZrCl/sb2$ as a catalyst is discussed. Additionally, the use of zirconium based catalysts to facilitate intramolecular diene cyclization is presented. Chapter 2. The development of the zirconium-catalyzed carbomagnesation of unactivated olefins into a diastereoselective reaction is achieved. High levels of diastereoselectivity were obtained for allylic and homoallylic alcohols and ethers. The mechanism of this reaction was initially studied using norbornenol as a mechanistic probe. The rigidity of this system enabled us to draw significant mechanistic conclusions. The mechanism of the zirconium-catalyzed carbomagnesation of acyclic substrates was then studied. The identity of the active catalyst, mechanism of alkylation and origin of selectivity in zirconacyclopentane cleavage were thoroughly investigated. Chapter 3. The first synthesis of the aglycon portion of the antifungal agent sch 38516 was accomplished applying our newly developed diastereo- and enantioselective carbomagnesation reactions, in addition to a variety of other new catalytic reactions. The synthesis was accomplished in 13 steps, nine of which employed metal catalysis. Two new tandem catalytic reactions were discovered and a novel Molybdenum catalyzed macrocyclic metathesis was performed.
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