Yield:172152-53-3 85%

Reaction Conditions:

with sodium acetate in acetic acid at 50; for 4 h;Product distribution / selectivity;

Steps:

1

[48] Water (100ml) and anhydrous sodium acetate (16.02g, 0.20mole) were added, and then 2-mercapto-5- aminobenzimidazole (32.27g, 0.20mole),2,5-dimethoxytetrahydrofuran (28.4g, 0.21mole), and acetic acid (100ml) were added. Then, stirring was carried out at 5O⁰C for 4 hours. The resultant product was cooled to 5⁰C and tetrahydrofuran (420ml) was added thereto. The mixture was neutralized with a sodium hydroxide aqueous solution, and water (130ml) was added to carry out layer- separation. Then, an organic layer was washed with a sodium hydroxide aqueous solution. The organic layer was dried by anhydrous magnesium sulfate and concentrated, and then crystallized by ethyl acetate and n-hexane to provide a final compound, that is, 5-(lH-pyrrol-l-yl)-2-mercaptobenzimidazole represented by Formula 3. Then, the obtained compound was confirmed.[49] M.P. 311.8⁰C. Direct inlet MS (EI) for C H N S m/z (relative intensity) 215 (M⁺,100)[50] ¹H NMR (200MHz, DMSO) δ 6.22 (t, 2H), 7.19 (m, 3H), 7.25 (t, 2H), 12.46 (b, IH)[51] Yield: 35.7g (85%)

References:

WO2009/151189,2009,A1 Location in patent:Page 5-6