Public defence of the Doctoral Thesis with Kaiheng Zhang

Fri 31 Mar 2023 16:44

On March 30th, 2023, Kaiheng Zhang presented his Doctoral Thesis in Chemistry and he passed it. Congratulations Kaiheng!

Three well-dressed people are standing in front of a large window

Title of the Thesis

Hiqhly enantioselective synthesis of lactam and sugar derivatives by chiral aminocatalysis and merging with transition metal catalysis

Abstract

This thesis presented novel methodologies for enantioselective synthesis of highly functionalized lactam and sugar derivatives. Asymmetric organocatalysis, cooperative dual catalysis and one-pot multicomponent reaction strategies were applied for the construction of continuous and quaternary stereogenic center.

In Chapter II, a unique strategy for enantioselective synthesis of bicyclic lactam N,S-acetals scaffolds was developed. The reaction intiates from an aminocatalyzed transformation. Next, the addition of thiol amine leads to the construction of bicyclic lactams via a imine/N,S-acetal formation/lactamization cascade sequence.

Chapter III focuses on a stereodivergent synthesis of fluorinated lactams bearing two vicinal stereogenic centers by multicomponent reaction. The reaction proceeds via enantioselective Michael addition /imine formation/lactamization cascade process. The reaction solvent used in the lactamizarion step gives switchable diastereoselectivity to the fluorinated quaternary stereocenter. DFT calculation revealed a mechanistic insight into the unexpected diastereoselectivity.

The usefulness of fluorinated lactams was demonstrated in fluorinated drug analogue synthesis. Chapter IV illustrates a new enantioselective allylic alkylation of acetonide protected trioses and furanosides by merging enamine catalysis with transition metal catalysis. An intrinsic sugar-assisted kinetic resolution mechanism between aldehyde and aminocatalyst was proposed and monitored in NMR studies.

Chapter V is about a new chiral amine-catalyzed C4’ α-aminomethyl-ation of furanoside and nucleoside derived C5’ aldehydes. The C4’ aminomethyl functionalized furanoside precursors have potentials for new nucleoside analogue synthesis.

 

Supervisor were Armando Cordova Professor Mid Sweden University

Opponent was Professor Andrei Malkov, Loughborough University, Storbritannien

Examination committee were professor Pavel Kocovsky from Charles University in Tjeckien, Professor emeritus Ari Koskinen from Aalto University in Finland, Professor Monica Ek from KTH and Professor Magnus Norgren, Mid Sweden University.

Link to the Thesis in DIVA


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The page was updated 3/31/2023