Hydrochloric Acid → 5-Amino-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine

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Reaction Steps

To a mixture of 4-(2-chlorophenyl)-2-ethyl-5-nitrothieno[2,3-b]pyridine (4.0 g), dioxane (25 ml) and conc. hydrochloric acid (12.5 ml) was added tin(II) chloride dihydrate (8.5 g). After stirring at room temperature for one hour, water was added to the mixture, which was made strong alkaline with 6N NaOH and then extraced with chloroform. The extract was washed with water and dried over MgSO4 and the solvent was distilled off. The residue was chromatographed on a silica gel column and eluted with hexane-ethyl acetate (4 : 1). The solvent was distilled off and to the residue was added hexane to obtain 5-amino-4-(2-chlorophenyl)-2-ethylthieno[2,3-b]pyridine (3.1 g, 85.6%) as crystals. The crystals were recrystallized from isopropyl ether to obtain colorless prisms, mp: 87°-88° C.

Provenance & Evidence