ISBN 9783843945165

978-3-8439-4516-5, Reihe Organische Chemie

Friederike Ratsch
Stereo-controlled cleavage of cyclobutanols through Ir-catalyzed C-C bond activation: Mechanistic studies and application in the Total Synthesis of (R,R,R)-α-tocopherol

458 Seiten, Dissertation Universität Köln (2020), Softcover, A5

Zusammenfassung / Abstract

The aim of this work was the development of new transition metal-catalyzed stereo-controlled C-C bond transformations which are at the same time atom-economic. The main focus lied on the enantioselective cleavage of cyclobutanols through iridium-catalyzed C-C bond activation. The mechanism was elucidated by means of deuteration experiments and kinetic isotope effect measurements and supported by DFT calculations. A substrate screening revealed a rather broad scope of the reaction with some limitations for certain functional groups. The new methodology was applied in the total synthesis of (R,R,R)-α-tocopherol to generate the quaternary center from a prochiral spiro[chromane-2,3'-cyclobutanol] unit. To introduce the aliphatic side chain of α-tocopherol, an unprecedented combination of enyne metathesis followed by 1,4-hydrogenation for the stereospecific synthesis of trisubstituted olefins was used.