Trifluoroacetic acid → Methyl 7-methoxy-2-oxo-1-(2-oxoethyl)-1,2-dihydroquinoline-4-carboxylate

Participants

Reaction Steps

To 0.19 g of methyl 1-(1,3-dioxolan-2-ylmethyl)-7-methoxy-2-oxo-1,2-dihydroquinoline-4-carboxylate, 2 mL of 90% aqueous trifluoroacetic acid solution was added and stirred for 14 hours. The solvent was removed under reduced pressure, and aqueous saturated sodium hydrogen carbonate solution and ethyl acetate were added. The organic layer was separated, and the aqueous layer was extracted with ethyl acetate. The organic layer and extracts were combined, washed with aqueous saturated sodium chloride solution, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure to give 0.19 g of methyl 7-methoxy-2-oxo-1-(2-oxoethyl)-1,2-dihydroquinoline-4-carboxylate. (2) To 3 mL of a dichloromethane solution containing 0.17 g of methyl 7-methoxy-2-oxo-1-(2-oxoethyl)-1,2-dihydroquinoline-4-carboxylate, 0.24 g of tert-butyl (2,3-dihydro-1,4-benzodioxin-6-ylmethyl)(piperidin-4-yl)carbamate and 34 μL of acetic acid were added and stirred for 1 hour. To the reaction mixture, 0.19 g of sodium triacetoxyborohydride was added and stirred for 1 hour. Ethyl acetate and aqueous sodium hydrogen carbonate solution were added, the organic layer was separated, and the aqueous layer was extracted with ethyl acetate. The organic layer and extracts were combined, washed with aqueous saturated sodium chloride solution, dried over anhydrous magnesium sulfate, and the solvent was removed under reduced pressure. The residue thus obtained was purified by silica gel column chromatography [eluent; chloroform:methanol=100:1] to give 0.25 g of methyl 1-(2-(4-((tert-butoxycarbonyl) (2,3-dihydro-1,4-benzodioxin-6-ylmethyl)amino)piperidin-1-yl)ethyl)-7-methoxy-2-oxo-1,2-dihydroquinoline-4-carboxylate as a brown oil.

Provenance & Evidence