Formaldehyde → Ethyl 6-iodo-1-(1-methylpiperidin-3-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

Ethyl 6-iodo-4-oxo-1-(piperidin-3-yl)-1,4-dihydroquinoline-3-carboxylate hydrochloride (Intermediate 132, 500 mg, 1.08 mmol) was suspended in methanol (15 mL) then 37% formaldehyde in water (405 μl, 5.4 mmol) and sodium cyanoborohydride (612 mg, 9.7 mmol) were added. The reaction was stirred at 23° C. for 16 h. The volume of the reaction was reduced by half and water (25 mL) was added. The suspension was extracted with 2:1 ethyl acetate: tetrahydrofuran (3×10 mL). The organic phases were combined, dried over sodium sulfate, and the solvent was removed in vacuo. The residue was passed through a plug of silica gel (2 g) eluting with 10% methanol in dichloromethane to remove any remaining borohydride. The solid was then dried in a vacuum oven at 50° C. for 18 h to give 386 mg (81% yield) of ethyl 6-iodo-1-(1-methylpiperidin-3-yl)-4-oxo-1,4-dihydroquinoline-3-carboxylate as an off white solid.

Provenance & Evidence