[2,2'-Bithiophene]-3,3'-dicarboxylic acid → Dithieno(3,2-c:2',3'-e)oxepine-4,6-dione

Participants

Reaction Conditions

Reaction Steps

Diacid (3) (12.6 g, 49.4 mmol) was stirred in 100 mL of acetic anhydride at reflux for 6 h. Upon cooling to 0° C., the solid was collected by filtration, washed with 20 mL of cold acetic anhydride, and dried in vacuo at 120° C. overnight. The resulting light yellow crystals (11.4 g, 98% yield) were used without further purification. Anal. Calcd. for C10H4O3S2: C, 50.84; H, 1.71. Found: C, 50.78; H, 1.66; 1H NMR (CDCl3): 7.68 (d, J=4.0 Hz, 2H), 7.40 (d, J=5.0 Hz, 2H); m.p. 260-263° C.; MS (EI): m/z (%) 235.96 (100) [M+].

Provenance & Evidence