Date of Award
Thesis and Dissertation
Master of Science (MS)
Department of Chemistry
Gregory M. Ferrence
This thesis reports the crystallization of two new quasiracemic crystals, the synthesis of a new oxadiazinanone, and the identification of crystals of two new compounds. In previous research the quasiracemates, (5,R,6,S)-4-cyclohexyl-5-methyl-6-phenyl-2H-1,3,4-oxadiazinan-2-one and (5S,6R)-4-isopropyl-5-methyl-6-phenyl-2H-1,3,4-oxadiazinan-2-one, were mixed in solution and crystallized. Instead of fractionally crystallizing, as would be expected, the compounds formed quasiracemic co-crystals. This suggested that other mixtures of oxadiazinanones would be possible candidates for studying compounds which fail to fractionally crystallize.
The first step in the process involves the synthesis of oxadiazinanones, using literature methods. A 4-step process is employed involving alkylation, nitrosation, reduction and cyclization. Because the starting material, norephedrine, is a chiral molecule, the desired enantiomer is synthesized starting with the proper enantiomer of norephedrine--either the (1S,2R) or (1R,2S) enantiomers. A new oxadiazinanone, (5R,6S)-4-cyclopentyl-5-methyl-6-phenyl-2H-1,3,4-oxadiazinan-2-one, was synthesized. After synthesis, the oxadiazinanones are mixed together and crystallized using vapor diffusion. X-ray diffraction is used to study the structures to determine the presence of quasiracemates.
From the sixteen racemic pairs compared, it was found that quasiracemic crystals were formed from oxadiazinanones containing either an N4-cyclopentyl substituent or an N4-cyclohexyl substituent. The quasiracemic crystal formed has a lower Z' than at least one of the quasienantiomers in the structure.
Two additional compounds were synthesized, and the crystal structures were identified. These crystals were obtained when the intended N4-ethylated and N4-n-butylated oxadiazinanones failed to cyclize in the final step of the oxadiazinanone synthesis.
Higgins, Patricia Ann, "Examination of Quasienantiomers of Oxadiazinanones Which Fail to Fractionally Crystallize" (2014). Theses and Dissertations. 203.