ChemInform Abstract: The Diyne Reaction of 3,3′‐Bis(phenylethynyl)‐2,2′‐bithiophene Derivatives via Rhodium Complexes: A Novel Approach to Condensed Benzo( 2,1‐b:3,4‐b′)dithiophenes.

Abstract

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Synthesis and Characterization of Bis[1]benzothieno[3,2-b:2′,3′-d]pyrroles: Quantitative Effects of Benzannulation on Dithieno[3,2-b:2′,3′-d]pyrroles

“…Although the earliest methods involved the cyclization of 3-nitro-2,2′-dibenzo[ b ]thiophene to give the unfunctionalized BBTP 1a [ 23 ] , which could then be N -functionalized, the majority of the known synthetic methods utilize a 3,3′-dihalo-2,2′-bi(benzo[ b ]thiophene) (either 4 or 5 ) from which the central pyrrole ring is formed via catalytic amination [ 24 , 25 , 26 , 27 ]. The intermediate 4 is not only the most common route to BBTPs, but also to other benzannulated species [ 35 , 36 , 37 , 38 , 39 , 40 ] such as thieno[3,2- b :4,5- b ’]bis[1]benzothiophene [ 36 , 38 , 40 ] and phospholo[3,2- b :4,5- b ’]bis[1]benzothiophene [ 37 ].…”

“…However, these reports either provide no synthetic procedure or details to support the claim [ 25 , 26 ], or the reported data is indicative of material of low purity, with one such report stating 4 to be a “purple brown solid” [ 24 ]. Most reports give more realistic yields of 40–56% via these basic methods [ 35 , 36 , 37 , 38 , 39 ]. In the optimized methods reported here, formation of the copper intermediate is facilitated by initial transmetallation with ZnCl 2 , followed by sequential reaction with CuCl 2 [ 15 , 41 ].…”

“…mp 169.0–171.0 °C (lit. mp 178 °C [ 35 ]); 1 H NMR (CDCl 3 ) δ 7.93 (dd, J = 1.2, 7.2 Hz, 2H), 7.87 (dd, J = 1.2, 7.2 Hz, 2H), 7.53 (dt, J = 1.2, 7.2 Hz, 2H), 7.49 (dt, J = 1.2, 7.2 Hz, 2H); 13 C NMR (CDCl 3 ) δ 139.2, 138.1, 129.4, 126.4, 125.5, 124.1, 122.3, 110.9. NMR data agree well with previously reported values [ 35 , 36 , 37 , 38 , 39 , 40 ].…”