An efficient synthesis of 5′-(4-cyanophenyl)-2,2′-bifuran-5-carbonitrile and analogues

Abstract

5′-(4-Cyanophenyl)-2,2′-bifuran-5-carbonitrile (6a) was prepared by two approaches. The first approach involves four steps, employs Stille coupling conditions utilising 2-tributylstannylfuran and 5-bromofuran-2-carboxaldehyde to furnish 3a in excellent yield. Oxime formation of 3a followed by acetic anhdride induced-dehydration gives the carbonitrile 4a, which on treatment with N-bromosuccinimide furnished 5a. A subsequent Suzuki coupling of 5a with 4-cyanophenylboronic acid gave 6a in good yield. The second approach used to prepare 6a involves cyanation of bromo-compound 10a with Cu(I)CN in DMF. Oligo-chalcophenes 7a–d were obtained via hexabutylditin-mediated homocoupling of respective brominated precursors 5a–d. Nitro-containing bichalcophenes 14 and 15 were obtained from the 1,4-dicarbonyl compound 13.