Cesium carbonate → Methyl 4-benzyloxythieno[2,3-c]pyridine-2-carboxylate

Participants

Reaction Steps

To an ice cold solution of Example 236B (4.2 g, 17 mmol) in anhydrous tetrahydrofuran (42 mL) under nitrogen atmosphere was added methyl thioglycolate (1.83 mL, 20.4 mmol) followed by powdered cesium carbonate (6.65 g, 20.4 mmol). Then the reaction mixture was allowed to warm to room temperature with stirring under nitrogen. After 30 minutes the reaction was refluxed for 15 minutes and cooled to room temperature. The reaction mixture was quenched with ice (50 mL) and partitioned with ethyl acetate (250 mL). The organic layer separated was washed with an ice cold solution of saturated NaCl (3×60 mL), dried (Na2SO4), and concentrated under reduced pressure to obtain the crude product which was recrystallized from methanol. The mother liquor was purified by flash chromatography on silica gel eluting with 7% acetone-hexane. The combined fractions gave the title compound in 55% yield (3.07 g). MS (APCI) m/e: 300 (M+H)+; 1H NMR (300 MHz, DMSO-d6) d: 3.92 (s, 3H), 5.42 (s, 2H), 7.35-7.47 (m, 3H), 7.52-7.57 (m, 2H, Ar—CH), 8.12 (s, 1H,), 8.36 (s, 1H), 8.98 (s, 1H).

Provenance & Evidence