Trifluoroacetic acid → methyl 9-bromo-2,3,4,5-tetrahydro-1H-1-benzoazonin-6-carboxylate

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Reaction Conditions

Reaction Steps

To a solution of methyl 9-bromo-1-(4-methoxybenzyl)-2,3,4,5-tetrahydro-1H-1-benzoazonin-6-carboxylate (12.5 g) in toluene (62.5 ml) was added trifluoroacetic acid (62.5 ml) and the mixture was stirred under nitrogen atmosphere at 80° C. for 7 hours. After distilling off the solvent under reduced pressure, water was added at 0° C. and the mixture was neutralized with potassium carbonate, and extracted with ethyl acetate. After washing the organic layer with aqueous saturated sodium bicarbonate solution and saturated brine, the resultant was dried with magnesium sulfate. The solvent was distilled off under reduced pressure, and the resulting residue was purified by silica gel column chromatography (hexane-ethyl acetate=9:1) and recrystallized from hexane:ethyl acetate to give methyl 9-bromo-2,3,4,5-tetrahydro-1H-1-benzoazonin-6-carboxylate (7.4 g) as yellow crystals.

Provenance & Evidence