Progress toward the synthesis of beta-branched Baylis-Hillman adducts via diastereoselective allenolate addition, and, Direct functionalization of tetrahydrofuran and other ethers with trimethylsilylketene, and, Synthesis and reactions of (eta6-phenyltric

Chapter 1. The Baylis-Hillman reaction was reviewed beginning with the initial discovery and organic mechanism. Many examples were cited that demonstrate both recent advancements and severe limitations. Finally, several alternative methods were cited that provide access to Baylis-Hillman adducts. Among them are the unique reactions that proceed through an allenolate intermediate. Development of an asymmetric version of the Baylis-Hillman reaction remains an elusive goal. The use of chiral auxillaries to control the addition of an allenolate to an electrophile has not been well documented. There remains a void that can only be filled by a general, diastereoselective reaction that can be used to synthesize beta-branched Baylis-Hillman adducts in high yield.;Chapter 2. We attempted to access high value beta-branched Baylis-Hillman adducts in a diastereoselective manner by utilizing an ambitious allenolate addition strategy. The 2-oxazolidinone chiral auxiliary, although widely applicable in many reactions, proved incompatible despite our diversified approaches. First, we ran into problems with allenolate instability and subsequent decomposition. Although this problem was eventually solved utilizing a hydroboration strategy, the opposite extreme of remarkable stability could not be overcome. A final effort was made by hydroalumination, but DIBAL failed to react with our substrate. Perhaps a different chiral auxiliary with a more reactive ester linkage may provide the necessary reactivity to undergo hydroalumination.;Chapter 3. We discoved a unique and operationally simple method to directly functionalize THF and other selected ethers utilizing TMS-ketene. Not only is this an unknown and potentially useful ketene reaction, it serves as a potential detrimental reaction of trimethylsilylketene in reactions employing ethereal solvents. We proposed a mechanism involving a new class of complex acyl oxonium ylide intermedieates and conducted experiments to support our proposal. We found much support and a single contradiction for our proposed mechanism from the official reviewers of a chemical publication. Extension of the reaction to more complex ketenes and ethers could provide a powerful new synthetic tool.;Chapter 4. We synthesized and fully characterized the previously unknown (eta6-phenyltricarbonylchromium) diazomethane (13). In addition to being a solid rather than an oil, and thus easier to work with, compound 13 has proven to be extremely stable relative to the uncomplexed form. Although we found no significant differences in selectivity, compound 13 does successfully participate in Rh(II) catalyzed cyclopropanations, as well as 1,3-dipolar cycloadditions with no appreciable decrease in yield. Complex 13 is also an important precursor to the as yet unreported chromium complex of phenyl carbene. We also successfully synthesized precursors (31 and 34) to two highly unique carbenes bearing one or two arene tricarbonylchromium substituents. Unfortunately we were not able to find conditions that permitted the formation and observation of these scientifically interesting carbenes. Since the preparation of the precursors should be easily reproducible, the possibility for further study has been facilitated.