Trifluoroacetic acid → HCID 66777568, compound

Participants

Reaction Steps

To a mixture of 3-methyl-1-(3-methyl-1-benzothiophen-2-yl)butan-1-one (1.00 g) synthesized in Example A32(1), methyl 6-aminopyridine-3-carboxylate (654 mg), triethylamine (4.79 mL) and dichloromethane (20 mL) was added titanium (IV) chloride (566 μL) at 0° C., and the mixture was stirred overnight at room temperature. Saturated aqueous sodium hydrogen carbonate solution was added to quench the reaction, and the 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 dark brown solid. To a mixture of the obtained solid, acetic acid (2 mL) and tetrahydrofuran (20 mL) was added sodium cyanoborohydride (540 mg), and the mixture was stirred at room temperature for 2 hr. Saturated aqueous sodium hydrogen carbonate solution was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:4, volume ratio) to give a pale-brown solid. To a mixture of the obtained solid, trifluoroacetic acid (1.00 mL) and ethanol (10 mL) was added sodium cyanoborohydride (251 mg), and the mixture was stirred at room temperature for 1 hr. In addition, sodium cyanoborohydride (251 mg) was added, and the mixture was stirred at room temperature for 30 min then at 50° C. for 1 hr. Saturated aqueous sodium hydrogen carbonate solution was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure to give the title object compound (743 mg, 47%) as a pale-yellow solid.

Provenance & Evidence