The epoxide deoxygenation reaction is formally the reverse of the
epoxidation reaction. Compared to epoxidation, which has reached its full
maturity, epoxide deoxygenation has not been as intensively developed.
Among the few deoxygenation reagents, a handful are catalytic in a metal
complex, show high stereospecificity and operate under mild conditions. A
common feature of all present deoxygenation reagents is that they do not
perform asymmetric deoxygenation of racemic epoxides.
Rhenium (VII) trioxo complexes are emerging as pliable catalysts for
epoxide deoxygenation. Designing a chiral rhenium (VII) trioxo complex
was our goal. Guided by the mechanism of rhenium (VII) trioxo catalyzed
epoxide deoxygenation and the mechanism of the stereogenic information
transfer, we have designed and prepared a chiral rhenium(VII) trioxo
complex. This complex is void of stereogenic centers and the source of
asymmetry is the restricted rotation around a carbon-carbon bond.
Detailed conformational analysis of the new chiral complex was done by
extensive NMR measurements and molecular modeling. The rotation
barrier for the diolate was experimentally and computationally estimated to
be 9.72 kcal/mol and 8.06 kcal/mol, respectively.
Unsuccessful attempts were made to prepare a camphor based
scorpionate because of the extreme steric congestion. A menthone based
scorpionate was successfully prepared. The related rhenium (TII) trioxo
complex with this scorpionate revealed contradicting chemical and
spectroscopic features. / Graduation date: 2005
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29844 |
| Date | 10 December 2004 |
| Creators | Juniku, Rajan B. |
| Contributors | Gable, Kevin P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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