Sodium Carbonate → 1-Methyl-2,4-bis(5-methylthiophen-2-yl)-1H-imidazole

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Reaction Steps

A mixture of 2-iodo-1-methyl-4-(5-methylthiophen-2-yl)-1H-imidazole 6 (1.31 g, 4.31 mmol), 5-methylthiophene-2-boronic acid pinacol ester (1.35 g, 6.03 mmol), Na2CO3 (1.80 g, 17.2 mmol) in H2O (10 mL) and DMF (40 mL) was degassed (N2 bubbling). Pd(PPh3)4 (125 mg) was added and the mixture was heated to reflux for 5 h. The mixture was allowed to cool to room temperature and concentrated. The mixture was diluted with EtOAc and H2O and the organic phase was separated. The aqueous phase was re-extracted (EtOAc) and the combined organics were washed (saturated aqueous NaCl), dried (MgSO4), filtered and concentrated to give a residue. The residue was purified by flash chromatography (EtOAc/hexanes 10:90 then 15:85 then 20:80) to give 1-methyl-2,4-bis(5-methylthiophen-2-yl)-1H-imidazole 7 (930 mg, 79%) as a colourless solid. A portion of this material was further purified by, firstly, recrystallisation (EtOAc/hexanes) and, secondly, by sublimation (130° C., 10−6 mBar): m.p. 138-140° C. 1H NMR (CDCl3, 400 MHz) δ2.48 (d, J=0.7 Hz, 3H), 2.51 (d, J=0.7 Hz, 3H), 3.76 (s, 3H), 6.64-6.67 (m, 1H), 6.73-6.77 (m, 1H), 7.00 (s, 1H), 7.10 (d, J=3.4 Hz, 1H), 7.14 (d, J=3.4 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ15.2, 15.3, 34.5, 117.0, 122.1, 125.5, 125.6, 126.7, 136.3, 137.7, 141.5, 142.4; HRMS (EI) m/z 274.0589 C14H14N2S2 [M]+. requires 274.0593.

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