24424-99-5

2133-34-8

51077-14-6

The general procedure for the synthesis of 1-Boc-L-acridine-2-carboxylic acid from di-tert-butyl dicarbonate and (S)-2-carboxycyclobutanamine was as follows:Example 15: (S)-1-(tert-butoxycarbonyl)azetidine-2-carboxylic acid (13). NaOH (420 mg, 10.5 mmol) was slowly added to a mixed solution of ethanol (20 mL) and water (10 mL) of (S)-2-azetidinecarboxylic acid 12 (1.0 g, 10.0 mmol) and di-tert-butyl dicarbonate (2.83 g, 12.5 mmol) at 0 °C. The reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the ethanol was removed by evaporation and diluted by adding water (20 mL), followed by adjusting the pH with dilute HCl to 3. Extraction was carried out with ethyl acetate (50 mL x 3) and the organic phases were combined. The organic phase was washed sequentially with water (30 mL) and saturated NaCl solution (30 mL) and then dried with Na2SO4. Evaporation to remove the ethyl acetate gave 1.98 g (100% yield) of target product 13 as a white solid.1H NMR (300 MHz, CDCl3) δ 4.79 (m, 1H), 3.93 (m, 2H), 2.46 (m, 2H), 1.48 (s, 9H).