Asymmetrische Rhodium-katalysierte Additionen an Cycloalkenone: Kinetische Racematspaltungen sowie NMR-gestützte Optimierung der 1,2-Addition von Trimethylaluminium

This thesis deals with asymmetric Rhodium/binap-catalysed addition reactions to cyclic alpha,beta-unsaturated ketones. Substituent effects in chiral starting materials can play a major role in synthetic applications due to double stereodifferentiation. Therefore, several substituted cyclohexenones were investigated regarding their behaviour in the 1,2-addition of trimethylaluminium as well as in the 1,4-addition of arylboronic acids or arylzinc chlorides (Hayashi-Miyaura reaction). A new example of a „regiodivergent reaction on a racemic mixture“ was discovered and new methodologies for kinetic resolutions were developed in this context. 31P NMR spectroscopic experiments toward the reaction mechanism subsequently led to the elaborate optimization of the reaction conditions by using a silver additive. To demonstrate the synthetic applicability of the thus formed enantiopure tertiary allylic alcohols, a formal total synthesis of the natural product frontalin was conducted.