Studies On The Construction Of Aryl-Substituted Chiral Carbon Centers By Michael Addition

In this thesis, we mainly aimed at the stereoseletive construction of the aryl-substituted chiral carbon centers. To address this topic, the asymmetric1,6-Michael addition reaction of quinone methide compounds was designed and preliminarily investigated. Besides featured by the construction of aryl-substituted chiral carbon centers strategically based on the Michael addition, we explored one synthetic route to the key tricyclic benzofuran intermediate, which was of importance in the chemical synthesis of Galanthamine-type alkaloids. The main contents of this thesis are divided into the following two parts:Part I:Methylene quinones (Quinone methides, QMs) are considered to be the important intermediates in many chemical and biological processes. However, due to its strong polarity and high reactivity, these kinds of compounds are quite prone to undergo dimerization and trimerization reactions, and most of the methylene quinones can not be stably separated by conventional purifying methods. So, the progress towards the study of the isolated methylene quinones was made slowly, particularly those based on its catalytic asymmetric reaction. In the context with the recent development of the catalysis of small organic molecules, the asymmetric1,6-Michael Addition between several isolated stable methylene quinones as a Michael receptor and malonates as a Michael donor was preliminarily explored and presented in this thesis.Part II:To asymmetrically access the crucial tricyclic core structure in the synthesis of (-)-galanthamine and (-)-lycoramine, one enantioselective route to the key tricyclic benzofuran intermediate was accomplished successfully base on the asymmetric Michael addition developed by our research group. The current synthetic efforts laid down a basis for the asymmetric total synthesis of the structurally related Amaryllidaceae alkoids.