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Thesis

Synthetic studies on polycyclic indole alkaloids

Authors: Wu, Tao (2006)

The first part of this work details the formal total synthesis of HKI 0231B and the first total synthesis of both demethyl HKI 0231A and demethyl HKI 0231B. The formal synthesis used TBAF as a mild reagent to construct the indole. The total synthesis featured an efficient radical cyclization / oxidation step to construct the skeleton and a DDQ-mediated methoxylation reaction. The second part of this work is dedicated to the synthetic efforts towards the abeo¬ergolines and the total synthesis of the abeo-ergoline analogs. In the synthetic study toward the abeo-ergolines, a reaction between 4-lithioindole and the enaminone, which was prepared from the ketone and Brederick reagent, effectively brought together all the necessary carbons for the final product. The synthesis of the abeo-...

Thesis

Synthetic studies toward the total synthesis of amphidinolide B1

Authors: Zhang, Wei (2006)

As one of the most potent cytotoxic compounds of amphidinolide family, amphidinolide B1 was isolated from a culture of amphidinium genus free-swimming dinoflagellate.l In addition to its intriguing bioactivity, amphidinolide B1 has some attractive structural features including a C13-C15 highly substituted diene, an unusual allyl epoxide moiety, nine stereocenters and 26-membered macrolactone skeleton. Although numerous synthetic efforts toward the total synthesis of amphidinolide B1 have been published, it remains an unconquered target. In our synthetic study, many useful protocols have been developed. To establish the C13-C15 diene, we applied a novel Fleming-type coupling and subsequent dehydration sequence. A highly diastereoselective chelation controlled aldol between aldehyde ...

Thesis

The synthesis and carbon dioxide reactivity of alkylaminozinc complexes

Authors: McDonnell, Ryan (2006)

A number of organometallic complexes utilize carbamate ligands to incorporate CO2 into new molecules. In order to better understand metal-carbamate chemistry, a series of CO2 reactive alkylaminozinc complexes were synthesized by the addition of dimethylzinc to secondary amines, resulting in the isolation of Zn(CH3)2(HNC4H8O)2, 1. The addition of one equivalent of CO2 to 1 resulted in the formation of the partially converted complex [Zn(CH3,)(HNC4H8O)(02CNC4H8O)]n, 2. Addition of CO2 in excess under anhydrous conditions formed the complex [Zn(02CNC4H8O)2]n, 3, and the addition of one quarter equivalent of H2O to 3 caused the formation of the Zn4(O2CNC4H8O)6 complex, 4. The kinetics of CO2 addition to 1 indicated the presence of a pentacoordinate zinc transition state that is responsi...