Date of Award

1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Mark L. McLaughlin

Abstract

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.

ISBN

9780591591248

Pages

107

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