New scorpionate ligands for catalysis and synthesis of oligocholate foldamers with various spacers using click chemistry

This thesis contains two chapters. The first chapter describes the design and synthesis of new oxazoline-based scorpionate ligands: the achiral compound hydrogen tris(4,4-dimethyl-2-oxazolinyl)phenylborate (H[ToM]) as well as the chiral compound lithium tris((4S)-4-isopropyl-2-oxazolinyl)phenylborate (Li[ToP]) and its protonated form hydrogen tris((4S)-4-isopropyl-2-oxazolinyl)phenylborate (H[ToP]). A series of ruthenium ((4S)-4-isopropyl-2-oxazolinyl) phenylborate complexes with different co-ligands, including {ruthenium(II)[tris((4S)-4-isopropyl-2-oxazolinyl)phenylborate]tris(acetonitrile)}tetraphenylborate {[Ru(κ3-ToP)(CH3CN)3]}BPh4, [ruthenium(II)tris((4S)-4-isopropyl-2-oxazolinyl)phenylborate (p-cymene)]chloride [Ru(κ3-ToP)(p-cymene)]Cl and ruthenium(II)[tris((4S)-4-isopropyl-2-oxazolynyl)phenylborate](cyclooctadiene)hydride Ru(κ3-ToP)(COD)H were designed and synthesized. The structure of {[Ru(ToP)(CH3CN)3]}BPh4 has been determined through NMR analysis and single-crystal X-ray diffraction. The κ3 coordination mode of ligand ToP was conformed in {[Ru(κ3-ToP)(CH3CN)3]}BPh4, which is similar to tris(pyrozolyl)borate ligand TP. Acetonitrile ligands in {[Ru(κ3-ToP)(CH3CN)3]}BPh4 are labile and could be replaced by pyridine, triphenylphosphine and trimethylphosphine. Reactivity of {[Ru(κ3-ToP)(CH3CN)3]}BPh4 has been systematically explored in several catalytic reactions, including allylic alkylation, dimerization of phenylalkynes and hydroamination. {[Ru(κ3-ToP)(CH3CN)3]}BPh4 was found to be effective in catalyzing dimerization of phenyl alkynes. All the compounds: {[Ru(κ3-ToP)(CH3CN)3]}BPh4, [Ru(κ3-ToP)(p-cymene)]Cl and Ru(κ3-ToP)(COD)H require further characterizations. The second chapter describes the design and attempted synthesis of several oligocholate foldamers. Extended oligocholates with various spacers in between the second and third cholate units were to be constructed through click chemistry, and labeled with 1-naphthylamine and dansyl chloride at the chain ends. The synthesis route has been paved out through the careful synthesis and characterization of different building blocks. New approach to monomer synthesis and new ways to construct the oligomers, which are expected to speed up the research in the future, were established during the exploration. Further effort in synthesis and fluorescence energy resonances transfer (FERT) study on the conformation change is needed to complete the project. Experimental condition of FERT and possible results of conformation change are discussed