Popis: |
The syntheses of benzo-fused benzo[2, 1-b:3, 4-b′]dithiophenes 1 and benzo[2, 1-b:3, 4-b′:5, 6-c″]trithiophenes 2 are described. The treatment of easily available 3, 3′-bis(phenylethynyl)-2, 2′-bithiophene derivatives 5a and 6 (via PdII-catalyzed alkynylation of the corresponding 3, 3′-dibromo-2, 2′-bithiophenes; see Scheme 1) with chlorotris-(triphenylphosphine)rhodium(I) yields the corresponding cyclic rhodium complexes 7 (Scheme 2) which smoothly react with acetylenes and sulfur to give 1 and 2 in good yields (Schemes 3–5). |