Thesis (M. Phil.)--University of Hong Kong, 1990.

Thesis (M. Phil.)--University of Hong Kong, 1991.

Thesis (Ph. D.)--University of Hong Kong, 1993.

No description available.

No description available.

The arylation of readily accessible N-tosyl hydrazones has been achieved using arynes generated in situ under mild conditions. The resulting N-tosyl-N-aryl hydrazones undergo a one-pot Fischer indole reaction on the addition of acid, giving a synthesis of protected indoles that avoids handling unstable intermediates and arylhydrazines. A new route to functionalised 2-(trimethylsilyl)phenyl triflate aryne precursors via Suzuki cross-coupling has been developed. The method allows the incorporation of a wide range of aryl and heteroaryl groups and reactions of arynes generated from these novel precursors have been demonstrated, including a cyclotrimerisation and a fluorenone synthesis. Work was also undertaken on aryne σ-insertion reactions. The addition of benzyne to ynamides was found to result in its net insertion between the nitrogen and acetylene species. The reaction proceeds from attack at the terminal carbon in an analogous manner to C(sp)–O insertions.

Ab initio Hartree-Fock and density functional theory calculations were carried out to investigate the structures, energies, and vibrational spectra of indole and two of its hydrogen migration tautomers. The calculated results of indole are in good agreement with experiments. Rotational constants and infrared spectral features of 2H-indole and 3H-indole are predicted to assist future experimental identification of the two tautomers. Transition states of unimolecular isomerization among the three tautomers are also optimized and activation barriers of the isomerization reactions evaluated. The results indicate that unimolecular indole → 3H-indole proceeds via 2H-indole with an activation barrier of 51 kcal/mol.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

This thesis is divided into two main chapters, which are focused on two separated and uncorrelated research areas. The first part of this thesis is dedicated to the research I carried out in benzyne chemistry and the second part is focused on catalytic C-H bond activation. In the first place, a novel insertion reaction of arynes into the nitrogen-carbonyl σ-bond of amides has been investigated as a rapid and powerful approach for the preparation of valuable ortho-disubstituted arenes. Readily available aromatic amides undergo smooth insertion when treated with O-triflatophenyl silane aryne precursors, producing versatile anthranilic derivatives in good to excellent yields. The process is entirely metal-free and has been expanded to the synthesis of biologically active heterocycles such as acridones and acridines. Secondly, the synthesis of medium-sized ring systems by intramolecular oxidative CH bond coupling has been explored. Despite the abundance of biologically active natural products featuring mediumsized rings, the synthesis of such ring systems using classical synthetic routes faces many challenges and has led to a dearth of medium ring compounds in medicinal chemistry. In contrast to the more facile 5-membered ring synthesis by oxidative C-H coupling, medium ring synthesis has not been previously reported using this approach. The chemistry, which requires zero pre-functionalisation of the substrates, is catalysed by palladium and has been exemplified using heteroaromatic substrates at the core of numerous biologically active molecules. The mechanism of the reaction has also been studied and a catalytic cycle has been proposed.