Acetic Acid → HCID 57428274, compound

Participants

Reaction Steps

To a solution of methyl 2-aminothiophene-3-carboxylate (1.76 kg, 11.2 mol) in glacial acetic acid (1.34 kg, 22.3 mol) and dichloromethane (8 L) were added trifluoroacetic acid (17.8 g, 156 mmol), 2,2-dimethoxypropane (6.83 kg, 65.6 mmol) and sodium triacetoxyborohydride (3.9 kg, 18.4 mol). The reaction mixture was stirred for 18 h at room temperature, quenched with saturated aqueous potassium carbonate solution (13.5 L) over 3 h and diluted with water (21 L). The organic layer was collected and the aqueous layer was extracted with dichloromethane (2×6 kg). The combined extracts were washed with aqueous sodium chloride solution (10 kg) and concentrated under reduced pressure to afford a dark black-red liquid (2.4 kg). This residue was purified on a 15-kg silica gel flash chromatography column eluted with 3% ethyl acetate-heptane to afford the title compound as a slightly yellow liquid.

Provenance & Evidence