One-pot desilylation-Sonogashira coupling

Abstract

Abstract Coupling of diethynyldiphenylsilane (1) with aryl halides under Sonogashira conditions affords the symmetrical diarylacetylenes bis(2-methylpyridin-5-yl)acetylene (2), bis(4-fluorophenyl)acetylene (3) and bis(4-trifluoromethylphenyl)acetylene (4) in 60% to 82% yield. In the case of 2, the by-product bis(2-methylpyridin-5-yl)butadiyne (2a) was isolated in 12% yield. The occurring desilylation reaction was investigated by treating bis(phenylethynyl)diphenylsilane (5) under the same conditions. The formation of 1-fluoro-4-(phenylethynyl)benzene (6), 1-trifluoromethyl-4-(phenylethynyl)benzene (7) and (tetrafluoropyridin- 4-yl)ethynylbenzene (8) in 70 to 84% yield and the cleavage of hexaphenylcyclotrisiloxane were observed in all cases.