Date of Completion
Field of Study
Doctor of Philosophy
This thesis demonstrates in many ways how the extraordinary structural stability of the porphyrin macrocycle redirects the reactivity of classic ring expansion reactions, delineating the limits of the “breaking and mending of porphyrins” approach toward pyrrole-modified porphyrins on the activity of octaethyl-2-oxochlorin and its derivatives.
The Baeyer-Villiger oxidations are potentially suited to generate such pyrrole-expanded porphyrinoids from known octaethyloxochlorin. However, the application of a number of Baeyer- Villiger oxidation conditions to this ketone merely led to the formation of novel or known porphyrinic meso-OH or N-oxide derivatives. Applied to octaethyloxochlorin oxime, a Beckmann rearrangement is potentially suited to generate a nitrogen-expanded porphyrinoid. Unexpectedly, this reaction led to a ring-expansion by an oxygen atom. The Schmidt reaction is an alternative to the Beckmann rearrangement to expand a cyclic ketone to a lactam. However, when applied toward the conversion of a synthetic porphyrin to a derivative containing a non-pyrrolic building block this approach failed to generate the expected lactam. Instead, a novel heptaethyl-2-hydroxy-chlorin-3-one and a somewhat regioselective chlorination of themeso-positions of the oxochlorin were observed. The work demonstrates how the extraordinary structural stability of the porphyrin macrocycle redirects the reactivity of classic ring expansion reactions, delineating some limits of the methodology to convert a pyrrole into a non- pyrrolic building block
We describe the oxidative ring-opening of octaethyl-2-oxochlorin using two different oxidation methods, providing a mixture of all possible regioisomeric products. The three major products were spectroscopically characterized (IR, MS, 1D- and 2D NMR spectroscopy) and their configurations were deduced
Li, Ruoshi, "Ring Expansion and Oxidative Transformations of Octaethyl-2-oxochlorin" (2018). Doctoral Dissertations. 1922.