Date of Award
Doctor of Philosophy (PhD)
Mark L. McLaughlin
This dissertation describes the preparation of two classes of compounds: cyclopentadienes and pyrroles. These compounds are key elements in the synthesis of conducting materials. A general novel methodology for the cyclopentadienylannulation of strained cycloalkynes has been developed. Bromination of 1,5-cycloctadiene produces 1,2,5,6-tetrabromocyclooctane, which under further treatment with DBU eliminates two moles of HBr to produce a mixture of 2 diastereomeric bisvinylbromides. These isomers eliminate one mol of HBr when treated with t-BuOK under phase transfer conditions producing a cyclooctene-yne. This bromoalkyne reacts in situ with dimethylfulvene in a sealed tube at 100$\sp\circ$C to produce a Diels-Alder adduct. Treatment of this adduct with t-BuOK eliminates one mole of HBr producing a new cyclooctyne. Diels-Alder reaction of this alkyne in situ with dimethylfulvene produces a mixture of two diastereomeric pentacyclo hydrocarbons. Mild hydrogenation of these hydrocarbons using 1 atm of H$\sb2$ and Ni-P2 reduces the less hindered double bonds producing a mixture of two diastereomers. Flash vacuum pyrolysis of these colorless reduced products at 550$\sp\circ$C produces a bright yellow bis(cyclopentadienyl) compound. A methodology to obtain acetylenepyrroles and arenepyrroles has been developed. N-potassium pyrrole reacts twice with tetrachloroethylene to produce a 1,2-dichloro-1,2-dipyrroleethylene, which under treatment with an equimolar amount of butyllithium produces dipyrroleacetylene. This alkyne trimerizes upon treatment with Vollhardt's catalyst producing hexapyrrolobenzene in 3% yield. This hexapyrrole derivative can be obtained in an improved 9O% yield by the reaction of hexafluorobenzene with N-potassium pyrrole. In the same way pentafluorobenzene, pentafluoropyridine, decafluoronaphthalene and 2,3-dichloroquinoxaline react with N-potassium pyrrole producing their corresponding substituted pyrrole derivatives. Treatment of 2-methylpyrrole with potassium in THF produces its N-potassium salt. Reaction of N-potassium-2-pyrrole with 2,3-dichloroquinoxaline and 2,3,5,6-tetrafluoropyridine produces the corresponding substitution products.
Davila, Alfonso, "Synthesis of Novel Cyclopentadienyl and Pyrrole Compounds." (1997). LSU Historical Dissertations and Theses. 6476.