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Exploratory organic photochemistry : internal epoxy ketones and medium sized dienes Gayler , Rudolf Erich

Abstract

In Part I of this work octahydro-4a, 8a-epoxy-l(2H)-naphthalenone, hexahydro-3a,6a-epoxy-l(2H)-pentalenone, and octahydro-3a,8a-epoxy-4(lH)-azulenone were photolyzed. The major course of these reactions was one of polymerization. Small amounts of monomeric products could however be obtained with difficulty and were tentatively assigned the structures which arise mechanistically via the same path as in the rearrangement of ordinary aliphatic α,β-epoxy ketones i.e, 1,3-diketone formation. In order to prove the structure of the photoproduct of the naphthalenone epoxide the synthesis of 2-cyclopentylidene-cyclopentanone oxide was attempted. In Part II of this thesis the nature of the excited state in the photolysis of cis, cis-cyclodeca-3, 8-diene-l, 6-dione was investigated by quenching and sensitization experiments. These suggested that the reactive excited state involved was a highly reactive triplet state. Furthermore, the thermal reaction of cis, trans-cyclodeca-3, 8-diene-1, 6-dione was investigated and found to give rise to three new products in low yields whose structures are still under investigation. They probably arose from an ene-reaction. Thermolysis of cis, cis-cyclodeca-3, 8-diene-1, 6-dione afforded 3a, 5, 8, 8a-tetrahydro-8a-hydroxy-4(1H)-azulenone. A low temperature photolysis of cis, trans-cyclodeca-3, 8-diene-l, 6-dione was carried out at 77°K in order to trap the potential intermediate trans, trans-cyclodeca-3, 8-diene-l, 6-dione. However, besides a minor amount of cis, cis-isomer, the low temperature photolysis afforded the same product as that obtained by photolysis at ambient temperature. Finally the centrosymmetric anti-configuration of the tricyclic photo-product from cis, cis-cyclodeca-3, 8-diene-l, 6-dione was further supported by a dipole measurement and by infrared and Raman spectroscopy.

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