Chiral amines are ubiquitous functionalities found in the architecture of the natural world and have been embedded into materials, catalysts, pharmaceuticals, agrochemicals, and bioactive natural products. However, limited approaches are accessible for the construction of an enantioenriched tertiary or quaternary-containing amine. This thesis describes the development of new methodologies for the synthesis of 7-membered nitrogen-containing heterocycle and 1,2-diamine compounds. Chapter one describes the application of dynamic kinetic asymmetric amination (DYKAT) of branched allylic acetimidates in the synthesis of 2-alkyldihydrobenzoazepin-5-ones. These 7-membered-ring aza-ketones are generated in good yield with high enantiomeric excess through sequential rhodium-catalyzed allylic amination with 2-amino aryl aldehydes followed by intramolecular olefin hydroacylation of the resulting alkenals. This two-step procedure is efficient, straightforward and convenient for the enantioselective preparation of these ring systems. In Chapter two, we further extended the methodology towards the allylic amination of racemic secondary and tertiary allylic trichloroacetimidates possessing β-nitrogen substituents, and proximal nitrogen-containing heterocycles, using the DYKAT transformation to provide branched allylic 1,2-diamines with high enantioselectivity. The catalytic system is versatile in the synthesis of 1,2-diamines possessing two contiguous stereocenters, with excellent diastereoselectivity. Additionally, the nitrogen-containing heterocycles suppress competing vinyl azirdine formation, allowing for the high enantioselective syntheses of 1,2-diamines possessing tertiary and quaternary centers. Chapter three gives a very brief outlook on our efforts in rhodium-catalyzed amination strategy in providing access to a variety of enantiopure α-fluoromethylated allylic amines.

Chitooligosaccharides are composed of linear β-(1→4)-linked 2-acetamido-2-deoxy-β-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-β-D-glucopyranose (GlcN). They are of interest due to their remarkable biological properties including antibacterial, antitumor, antifungal and elicitor activities. They can be obtained from the aminoglucan chitosan by chemical or enzymatic degradation which obviously affords rather heterogenous mixtures. On the other hand, chemical synthesis provides pure compounds with defined sequences of GlcNAc and GlcN monomers. The synthesis of homo- and hetero-chitobioses and hetero-chitotetraoses is described in this thesis. Dimethylmaleoyl and phthaloyl groups were used for protection of the amines. The donor was activated as the trichloroacetimidate in order to form the β-linkages. Glycosylation in the presence of trimethylsilyl trifluoromethanesulfonate, followed by N- and O-deprotection furnished chitobioses and chitotetraoses in good yields. / Chitooligosacchride bestehen aus linear β-(1→4)-verknüpften 2-acetamido-2-deoxy-β-D-glucopyranose (GlcNAc) and/or 2-amino-2-deoxy-β-D-glucopyranose (GlcN) Einheiten. Sie beanspruchen aufgrund ihrer bemerkenswerten biologischen Eigenschaften – u.a. antibakterielle, antitumor, antimykotische und Elicitor Aktivität - grosses Interesse. Sie sind durch chemischen oder enzymatischen Abbau von Chitosan zugänglich, wobei diese Methoden unausweichlich zu komplexen, sehr heterogenen Mischungen von Chiooligosacchariden führen. Chemische Synthesen von Chitooligosacchariden mit definierter Sequenz von GlcNAc und GlcN Einheiten sind daher von erheblichem Interesse. In der vorliegenden Arbeit werden Synthesen von partiell acetylierten Chitobiosen und –tetraosen beschrieben. Die Aminogruppen wurden als N-Dimethylmaleoyl- bzw. Phthaloylimide geschützt. Die Donoren wurden als Trichloacetimidate aktiviert, wobei aufgrund von Nachbargruppeneffekten ausschliesslich die β-Glycoside entstehen. Die Trimethylsilyltrifluoromethansulfonat-promovierte Glycosidierung geeigneter Akzeptoren lieferte schliesslich die Chitobiosen und die Chitotetraosen in guten Ausbeuten.