Triphenylphosphine → 2-Methoxy-6-(6-methoxy-4-((5-phenyl-1,3,4-thiadiazol-2-yl)methoxy)benzofuran-2-yl)imidazo[2,1-b][1,3,4]thiadiazole

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In a 200 mL round-bottomed flask, benzene was added to ethyl 5-phenyl-1,3,4-thiadiazole-2-carboxylate (Example 8B, 80 mgs, 0.252 mmol) and 6-methoxy-2-(2-methoxyimidazo[2,1-b][1,3,4]thiadiazol-6-yl)benzofuran-4-ol (Example 1H, 58.2 mgs, 0.303 mmol) and the mixture was sonificated for 30 sec. and concentrated in vacuo to remove traces of water in the starting material. Triphenylphosphine (99 mgs, 0.378 mmol) was added and the mixture was dried on high vacuum for 10 min. THF (40 mL) were added and the mixture was sonificated/heated for 5 min. Diisopropyl azodicarboxylate (68.6 μl, 0.353 mmol) in THF (4 mL) was added dropwise on app. 1 h and LC/MS showed that the reaction was not complete. Diisopropyl azodicarboxylate (2 drops) were added again and the mixture was diluted in CH2Cl2, washed with sat. aqueous NaHCO3 (1×), brine (1×), and dried over anhydrous MgSO4 and concentrated. The residue was purified on silica gel chromatography (100% CH2Cl2 up to 15% EtOAc/CH2Cl2) to give a residue which was triturated with MeCN and afforded the title material (36 mgs, 29%). LC (Method A): 2.901 min. HRMS (ESI) calcd for C23H17N5O4S2 [M+H]+ m/z 492.0722, found 492.0806. 1H NMR (CDCl3, 400 MHz) δ ppm: 7.96-8.02 (m, 2H), 7.87 (s, 1H), 7.45-7.55 (m, 3H), 7.10 (s, 1H), 6.73-6.78 (m, 1H), 6.48 (d, J=1.57 Hz, 1H), 5.63 (s, 2H), 4.22 (s, 3H), 3.86 (s, 3H).

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