Synthesis and study of some novel and interesting cyclophanes

Houghton, Tom J. (1999) Synthesis and study of some novel and interesting cyclophanes. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

The somewhat vague title of this thesis is due to the fact that several fairly loosely-connected projects were investigated, the common thread being the classification of all the targets as "cyclophanes". [For a definition of this term see Chapter 1.] This approach has naturally had its disadvantages, but it has allowed the author the opportunity to explore some fascinating concepts and methodologies. -- The idea of a tethered-cyclophane-based molecular switch was investigated in Chapter 2. This work led to a new thiacyclophane-forming methodology, and ultimately to the observation of the desired syn-anti equilibrium process sought at the outset. This process was studied by dynamic NMR, and the thermodynamic data for the process, including the transition state, calculated. -- The previous project was expanded to the study of cyclophanes and pyrenophanes bridged by crown ether tethers. Two tethers were used, corresponding to 15-crown-5 and 18-crown-6. The target compounds were successfully synthesised and their conformational properties predicted by computational studies and observed by NMR. -- Two C₂-symmetric chiral tetra-functionalised [2.2]paracyclophanes were synthesised, paving the way for the synthesis of some interesting chiral ligands. In the course of this study a much-simplified and very economical apparatus for flash vacuum thermolysis was developed. -- A dithiatetraynophane, a tetraynophane and an enediynophane were synthesised. -- Finally, a new class of "esterophane" was synthesised. The structural features of one example were studied by X-ray crystallography, and a computational analysis performed.

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