Asymmetric synthesis of functionalised Pyrrolidines and their application in Total Synthesis

The intramolecular aza-Michael reaction has been used effectively in the synthesis of nitrogen heterocycles, with several efforts made in recent years to do so asymmetrically. The selection of the Michael acceptor can play an important role in both the rate and enantioselectivity of the reaction. The research in this thesis demonstrates how the use of a chiral phosphoric acid can catalyse the intramolecular asymmetric aza-Michael reaction of a protected amine with an α,β- unsaturated thioester. The scope of the reaction was demonstrated in the synthesis of 2,2- and 3,3-spirocyclic pyrrolidines in high yields and enantioselectivity. The synthesis of an unsubstituted pyrrolidine provided the core of two natural products (R)- bgugaine and (R)-irnidine and both succumbed to total synthesis. (R)-Bgugaine was synthesized in a 33% overall yield in 6 steps while (R)-irnidine was synthesized for the first time in an overall yield of 18% over 6 steps.