Syntheses of Acetylenes Substituted with Heteroaromatic Containing Trifluoromethyl Groups

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1. Fluorination of 2-carboxylic acids of heteroaromatics, such as furan, thiophene and N-methylpyrrole, by sulfur tetrafluoride were attempted to give only, tarry polymeric materials. 2,5-Dicarboxylic acids of furan and thiophene, however, afforded 2,5-bis (trifluoromethyl) furan and thiophene together with 5-trifluoromethy1-2-carboxylic acids of the corresponding heteroaromatics by fluorination with sulfur tetrafluoride. 2-Trifluoromethylfuran and thiophene were synthesized by decarboxylation of the 2-trifluoromethyl-5-carboxylic acids on heating in the presence of copper powder.2. The lithiated furans and thiophenes containing trifluoromethyl groups were treated with 1,1-dichloro-2,2-difluoroethylene to give the corresponding furans and thiophenes with a 1-fluoro-2,2-dichlorovinyl group, which was then converted to a ethynyl group by dehalogenation with n-butyllithium.3. Several trifluoromethyl-substituted furans and thiophenes with a ethynyl group were polymerized using a catalyst such as WC1_6-Ph_4Sn, to yield the corresponding polyacetylenes. 2,5-Bis (trifluoromethyl)-3-ethynylfuran and thiophene were found to give a high molecular weight polyacetylenes.