Triethylamine → 2-(Methoxycarbonyl)-5-nitrophenyl 4-methylpiperazine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a dry flask are added 2-hydroxy-4-nitro-benzoic acid methyl ester (40 mmol) (from Example 1h) and triphosgene (26.6 mmol) and DCM (100 mL). The reaction mixture is cooled to 0° C. and diisopropylethylamine (40 mmol) is added slowly. After addition the mixture is warmed to rt. After 1 h at this temperature it is refluxed for 1 h. The mixture is cooled down and the solvents are removed. THF (100 mL), Et3N (80 mmol), and N-methyl piperazine (80 mmol) are added and the mixture is stirred at rt overnight. The solvent is removed and the residue dissolved in EtOAc. Phases are separated upon addition of a 10% solution of NaHCO3. The organic phase is washed with brine, dried on Na2SO4 and evaporated. The crude is used in the following reaction.

Provenance & Evidence