A Synthetic Methodology Towards the Construction of Spirocyclic Ethers
Leslie Laguna & Ruquia Ahmed-Schofield*
Department of Chemistry, Goucher College
1021 Dulaney Valley Rd., Baltimore, MD 21204
Introduction
Many natural and biologically important molecules contain a spirocyclic
ether as part of their structure. It can be found in molecules isolated from
the genus Leonorus where some have been used in the treatment of
cardiovascular diseases, antitumor, sedatives, and uterotonics. This
structural feature is also present in tea (theaspirane), vanilla (vetispirane),
and red wine grape skins. Our research aims to construct spirocyclic ethers
by the photodecomposition of cyclic derivatives of Barton PTOC esters with
alcohol nucleophiles.
Conclusions
Cyclic PTOC Ester Derivative Synthesis:
Make Varying Ring Sizes
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Cycloheptyl Barton PTOC ester derivative (n=3) has been synthesized
Its photodecomposition yielded the spirocyclic ethers, but in low yields.
The photodecomposition also yielded two by-products.
The use of CHCl3 to replace t-BuSH in the irradiation step was successful.
Previous Studies
In 2006, we reported the synthesis of a cyclohexyl PTOC ester derivative
and its photodecomposition in allyl alcohol.
Photodecomposition Result of Cycloheptyl PTOC Ester
The photodecomposition in the presence of allyl alcohol proceeded through
a mechanism involving the 5-exo-trig ring closure reaction of a radical
intermediate to yield spirocyclic ethers.
Future Studies
Acknowledgments
• Dr. Ruquia Admed-Schofield, Research Advisor*
• Department of Chemistry, Goucher College
• Claasen Research Fund
Future studies include the variation of the cyclic PTOC ester derivative and
the alcohol nucleophile, the use of CHCl3 to replace the potent smelling tBuSH, and the use of substituted benzaldehyde in the Aldol Addition step
of the synthesis. Changes in ring sizes, incorporation of selected functional
groups, as well as chiral induction studies can also be conducted to target
specific molecules.