Palladium-Catalyzed Synthesis of Alkynylated 1,4:5,8:11,14:15,18-Tetrasulfido[20]annulenes

The syntheses of tetraalkynylated tetrasulfido[20]annulenes 2a−d are described. Treatment of the corresponding brominated tetrasulfido[20]annulene 5a (easily available by McMurry coupling of the brominated 2,2′-bithiophene-5,5′-dicarbaldehydes, 3a) with various acetylenes in the presence of Pd(II) and Cu(I) in NH(iPr)2 yields acetylenic tetrasulfido[20]annulenes 2a−d.