2-[2-[(Ethoxycarbonyl)amino]ethyl]-6-methoxyphenyl ethyl carbonate → Ethyl 6-methoxy-1-oxo-1,2,3,4-tetrahydroisoquinolin-5-yl carbonate

Participants

Reaction Conditions

Reaction Steps

Into a 500-mL 3-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed polyphosphoric acid (PPA, 150 g). This was followed by the addition of 2-[2-[(ethoxycarbonyl)amino]ethyl]-6-methoxyphenyl ethyl carbonate (20 g, 64.24 mmol, 1.00 equiv) at 145° C. The resulting solution was stirred for 20 min at 140-145° C. The reaction mixture was cooled to room temperature with a water/ice bath. The resulting solution was diluted with 500 mL of ethyl acetate and 500 mL of water. The resulting mixture was washed with 3×300 mL of water. The mixture was dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column with ethyl acetate/petroleum ether (1:1). This resulted in 1.5 g (9%) of ethyl 6-methoxy-1-oxo-1,2,3,4-tetrahydroisoquinolin-5-yl carbonate as a gray solid. MS (ESI) m/z 266 ([M+H]+).

Provenance & Evidence