[S:1]1[C:5]2[S:6][CH:7]=[CH:8][C:4]=2[CH:3]=[CH:2]1.Cl[C:10]([C:12]1[CH:13]=[C:14]([CH:18]([CH3:21])[C:19]#[N:20])[CH:15]=[CH:16][CH:17]=1)=[O:11].[Cl-].[Al+3].[Cl-].[Cl-]>C(Cl)Cl>[S:1]1[C:5]2[S:6][CH:7]=[CH:8][C:4]=2[CH:3]=[C:2]1[C:10]([C:12]1[CH:13]=[C:14]([CH:18]([CH3:21])[C:19]#[N:20])[CH:15]=[CH:16][CH:17]=1)=[O:11]A mixture of thieno[2,3-b]thiophene (23.8 g) and 2-(3-chloroformyl-phenyl)propionitrile (29.6 g) is added dropwise to a suspension of anhydrous aluminium chloride (50 g) in methylene chloride (425 cc). After 16 hours at 25° C., the reaction mixture is heated under reflux for 40 minutes and then, after cooling, distilled water (600 cc) and 12 N hydrochloric acid (50 cc) are added. The organic phase is decanted and the aqueous phase is extracted twice with methylene chloride (total 200 cc). The combined methylene chloride solutions are washed three times with distilled water (total 1500 cc), and then stirred with 5 N aqueous sodium hydroxide solution (50 cc) for 2 hours at 25° C. The organic phase is decanted, washed four times with distilled water (total 2000 cc) and dried over anhydrous sodium sulphate, decolourizing charcoal (5 g) is added, and the organic phase is filtered and evaporated. The residue obtained (43.6 g) is chromatographed on a column (4.8 cm diameter, 47 cm height) containing silica gel (410 g). Elution is carried out with methylene chloride (total 1500 cc). The first fraction (500 cc) is discarded, whilst the two following fractions are combined and concentrated to dryness. 2-{3-(Thieno[2,3-b]thien-2-yl)carbonylphenyl}propionitrile (16.9 g) is obtained in the form of an oil. Rf=0.60 (silica gel chromatographic plate; solvent: methylene chloride).
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