Rhodium-catalyzed transformation of heteroaryl aryl ethers into heteroaryl fluorides
A rhodium complex catalyzed the conversion of the C-O bond of heteroaryl aryl ethers to the C-F bond. The reaction of (4-chlorophenylthio)pentafluorobenzene with heteroaryl aryl ethers provided heteroaryl fluorides and heteroaryl (4-chlorophenylthio)tetrafluorophenyl ethers; this involved the cleavage of a single heteroaryl C-O bond under equilibrium conditions. The reaction of heteroaryl aryl ethers with 2-fluorobenzothiazole in which two heteroaryl and aryl C-O bonds were cleaved provided heteroaryl fluorides and aryl fluorides. The reactions were applicable to five-membered and six-membered heteroaryl aryl ethers and also to diaryl ethers possessing one or two electron-withdrawing groups.
Silver-Catalyzed C-H Trifluoromethylation of Arenes Using Trifluoroacetic Acid as the Trifluoromethylating Reagent
Direct trifluoromethylation of arenes using TFA as the trifluoromethylating reagent was achieved with Ag as the catalyst. This reaction not only provides a new protocol for aryl C-H trifluoromethylation, but the generation of CF3· from TFA may prove useful in other contexts and could potentially be extended to other trifluoromethylation reactions. (Chemical Equation Presented).