I. Studies in Isomerism: Permutations, Point Group Symmetries, and Isomer Counting. II. Studies in the Photochemistry of Coumarin and Certain Coumarin Derivatives

Citation

Leonard, Jack Edward (1971) I. Studies in Isomerism: Permutations, Point Group Symmetries, and Isomer Counting. II. Studies in the Photochemistry of Coumarin and Certain Coumarin Derivatives. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0WGY-7455. https://resolver.caltech.edu/CaltechTHESIS:06112018-091948944

Abstract

PART I

Polya's group theoretical method for calculating the permutation isomers of a rigid molecular framework is extended to certain nonrigid systems. Symmetry operators are defined which allow the high symmetry of freely rotating, rapidly inverting, or ring-flipping molecules to be handled by group theoretical methods.

In the second portion of this discussion the effect of chiral ligands on the number of possible permutation isomers is discussed and a number of unusual possible meso compounds are presented.

PART II

The unusually high rate of energy dissipation in coumarin is discussed. In the raman spectrum of ultraviolet irradiated coumarin at 98°K evidence is found for the formation of an oxabicyclobutane derivative via the rearrangement:

[Diagram included in scanned thesis' abstract, p. iv.]

Bands at 875 and 1231 cm^-1 in the raman spectrum appear to arise from the oxabicyclobutane. When coumarin (or N-alkyl o-coumaramides) is irradiated in amine solution, N,N'-dialkyl-o-tyrosine amide derivatives are formed. This is a new pathway to o-tyrosine derivatives, but its generality is not known.

Thesis Files