General procedure for the synthesis of 1-(4-nitrobenzyloxycarbonyl)benzotriazole from benzotriazole and p-nitrobenzyl chloroformate:
- P-nitrobenzyl chloroformate (0.5 mmol) was dissolved in 5 mL of dichloromethane, triethylamine (2 mmol) was added as a base followed by benzotriazole (0.5 mmol).
- The reaction mixture was stirred at room temperature overnight. After completion of the reaction, the reaction solution was diluted with 20 mL of dichloromethane and washed sequentially with 3 x 5 mL of 1N hydrochloric acid, 2 x 5 mL of 1N sodium hydroxide solution and 1 x 5 mL of saturated saline.
- The organic phase was separated, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to remove the solvent.
- The residue was ground with ether to give a light yellow solid product in 59% yield with a melting point of 160-162 °C. The structure of the product was confirmed by NMR.
- The structure of the product was confirmed by nuclear magnetic resonance hydrogen spectroscopy (1H NMR), nuclear magnetic resonance carbon spectroscopy (13C NMR) and high resolution mass spectrometry (HRMS):
1H NMR (CDCl3) δ 8.27 (d, 1H, J = 8.9 Hz), 8.17 (m, 3H), 7.72 (d, 1H, J = 8.9 Hz), 7.65 (td, 1H, J = 8.3 Hz, 1.1 Hz), 7.53 (m, 2H), 5.26 (s, 2H).
13C NMR (CDCl3) δ 154.84, 146.17, 142.27, 141.30, 132.01, 130.82, 128.78, 126.37, 124.16, 120.86, 113.58, 68.66.
HRMS (FAB) calculated value C14H11N4O4 ([M+H]+): 299.0775, measured value: 297.0775.
