Oxalyl chloride → N1-[2-[2-(tert-butoxycarbonylamino)ethoxy]-4-methoxybenzoyl]-N2-(4-methoxybenzoyl)-1,2-benzenediamine

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Reaction Steps

2-[2-(tert-Butoxycarbonylamino)ethoxy]-4-methoxybenzoic acid (187 mg, 600 μmol) was suspended in 3.5 ml of CH2Cl2 under nitrogen, then 50 μl DMF was mixed in, followed by oxalyl chloride (63 μl, 720 μmol, 1.2 equivalents). Significant evolution of gas was observed upon oxalyl chloride addition. The clear solution was stirred at room temperature a few minutes, transferred to a 50 ml flask containing 5 ml toluene and stripped of volatiles on a rotary evaporator. The cloudy oil was resuspended in 5 ml of toluene and stripped again of volatiles to provide a cloudy oil. The oil was suspended in 10 ml of amylene-stabilized CHCl3 and added to a chilled suspension of N1-(4-methoxybenzoyl)-1,2-benzenediamine (122 mg, 500 μmol, 0.8 equivalents) also in 10 ml of amylene-stabilized CHCl3. Next was added 200 μl of pyridine (2.47 mmol, 4 equivalents) to the mixture, and it was stirred on ice under a blanket of nitrogen. The slurry cleared to give a pale yellow solution within 10-15 min after pyridine addition. Stirring was continued on ice overnight, then at room temperature for a few hours. The clear mixture was diluted with 30 ml CH2Cl2 and washed once each with dilute NaHSO4 and water. The organic layer was dried over Na2SO4 and concentrated to give a brown oil that was subsequently purified on a 2 mm thick chromatotron rotor using 1:1 hexanes:EtOAc as eluent. There was obtained N1-[2-[2-(tert-butoxycarbonylamino)ethoxy]-4-methoxybenzoyl]-N2-(4-methoxybenzoyl)-1,2-benzenediamine (201 mg, 62%) as a brittle off-white foam after drying the pure fractions from the chromatotron plate.

Provenance & Evidence