Ammonium Chloride → 3-Methylthieno[3,2-b]pyridine-2-carbaldehyde

Participants

Reaction Steps

To a mixture of ethyl 3-methylthieno[3,2-b]pyridine-2-carboxylate (3.00 g) synthesized above, calcium chloride (3.02 g), ethanol (30 mL) and tetrahydrofuran (30 mL) was added sodium borohydride (2.06 g) at 0° C., and the mixture was stirred at room temperature for 5 hr. Saturated aqueous ammonium chloride solution was added to quench the reaction, and the reaction mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure to give a white solid. To a solution (50 mL) of the obtained solid in tetrahydrofuran was added active manganese dioxide (12.2 g), and the mixture was stirred at 50° C. overnight. Manganese dioxide was filtered off, and the filtrate was concentrated under reduced pressure to give the title object compound (2.24 g, 93%) as a white solid.

Provenance & Evidence