UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Photochemistry of dibenzobarrelenes and [alpha]-adamantyl acetophenones in both the solution and crystalline state Yang, Jie


Six di- and mono- aryl substituted dibenzobarrelene derivatives were synthesized for studies of the di-n-methane rearrangement in both solution and the solid state. The starting materials and their photoproducts were characterized by spectroscopic methods. The photoproduct ratios of these dibenzobarrelene derivatives in the di-it-methanere arrangement, in both the solution and solid state, were determined. Based on the X-ray crystal structures and Molecular Mechanics calculations (MMX), the regioselectivities of these dibenzobarrelene substrates in the multi-channel di-n-methane rearrangement were discussed in terms of electronic effects and intramolecular steric effects. A series of a-adamantyl acetophenone derivatives were synthesized for the structure-reactivity correlation studies in the solid state Norrish type II photoreactions. The structure assignments of both the starting substrates and the diastereomeric photoproducts were primarily based on NMR techniques, such as HETCOR and NOE experiments. The X-ray crystal structures of four a-adamantyl acetophenones were determined, and their solid state reactivities were discussed relative to the proposed ideal geometric requirements for hydrogen abstraction. Chiral crystals of carboxylic acid-amine salts were synthesized for solid state asymmetric induction studies. Some of these chiral salts were made from a prochiral, carboxylic acid group-containing a-adamantyl acetophenone (119) and optically pure chiral amines. The solid state photolyses of these chiral salts afforded photoproducts in optially active form (12%-97% e.e.). The solid state structure-reactivity was discussed based on X-ray crystal structures of crystals of these starting chiral salts. The absolute configuration correlation between a chiral crystalline salt 169n and its major photoproduct 159s was established, which revealed that salt 169n reacted stereospecifically via a topochernically allowed pathway to give a single diastereomer of photoproduct 159s. A macrocyclic diketone 108b was synthesized. It was found that this diketone did not undergo the Norrish type II reaction in the crystalline state. The hydrogen abstraction geometry of this diketone was analysed based on its crystal structure, and the distances between 7-hydrogens and the carbonyl oxygens were found to be beyond the proposed maximum abstracting distance of 3.0 A. Pyrazinone 197 and pyrazinethione 199 were synthesized for the solid state [4 +4] photocycloaddition reactions. It was found that pyrazinone 197 gave high optical yield of the photoproduct 198 (95% e.e.); this result was discussed based on the crystal structure of the substrate 197. Pyrazinethione 199 was found photochemically unreactive.

Item Media

Item Citations and Data


For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.