Session: Undergraduate Research Posters: Organic Chemistry:

The preparation of macrocyclic organic molecules containing pi-conjugation is a focus of our group. Structures of this type are expected to show directed energy and electron transfer and thus should be effective in the preparation of photoreactive materials such as electronic sensors or light harvesting materials. The syntheses of several macrocyclic model systems, with varying degrees of conjugation will be presented. All of the model structures can be prepared from the same key intermediate structure, (3-ethynylphenoxy)(tert-butyl)dimethylsilane. This key intermediate was prepared from the commercially available 3-hydroxybenzaldehyde. Protection of the hydroxyl with tert-butyldimethylsilyl chloride in the presence of a weak base (imidazole), under microwave conditions gave the protected compound in 94% yield. Next the aldehyde functional group was converted into the alkyne via Corey-Fuchs olefination reaction conditions. This involved reacting with an ylide (formed from carbon tetrabromide, triphenylphosphine and zinc) to give the dibromide in high yield. The second part of the olefination was accomplished by reaction of the dibromide with n-butyllithium to give the key intermediate. Sonogashira coupling (palladium / copper(I) iodide catalyst) of the alkyne with aryl halides gave polyphenylethynylarenes in high yields. Cyclization of the polyphenylethynylarenes alcohols can be accomplished under dilute conditions via nucleophilic substitution reactions.

Dr. Trent Selby

Associate Professor, Mississippi College

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