Oxalyl chloride (0.38 mL, 4.33 mmol) was added to the crude Troc-protected anthranilic acid, prepared in the previous reaction, together with 2 drops of dry DMF in dry dichloromethane (30 mL). After initial strong effervescence, the mixture was allowed to stir at room temperature overnight. The resulting acid chloride was added dropwise, over 30 minutes, to a solution of 2S-(+)-pyrrolidinemethanol (0.44 g, 4.33 mmol) and TEA (1.37 ml, 9.85 mmol) of dry dichloromethane (15 mL) at −16° C. The reaction mixture was diluted with ethyl acetate (20 mL), and washed with dilute HCl (1N, 2×30 mL), satd. aqueous NaHCO3 (2×30 mL), water (30 mL) and brine (30 mL). The organic layer was then dried over MgSO4 and evaporated to give a yellow oil. The crude product was purified by flash chromatography (petroleum ether/ethyl acetate=50/50) to yield the product (1.2 g, 70%) as a pale yellow oil: 1H NMR (270 MHz, CDCl3) δ1.75 (m, 2H); 1.92 (m, 1H); 2.17 (m, 1H); 3.53 (m, 2H); 3.72 (m, 1H); 3.86 (s, 3H); 3.93 (s, 3H); 4.19 (m, 1H); 4.43 (m, 1H); 4.77 (d, J=12 Hz, 1H); 4.85 (d, J=12 Hz, 1H); 6.85 (s, 1H); 7.69 (s, 1H); 9.08 (bs, 1H). 13C NMR (67.8 MHz, CDCl3) δ25.1; 28.2; 51.4; 56.0; 56.4; 60.8; 65.9; 74.4; 95.3; 104.7; 110.7; 116.3; 130.8; 144.4; 151.0; 152.1; 170.4. MS: m/e (relative intensity) 454 (M−1, 5), 356 (3), 306 (10), 275 (5), 206 (100), 179 (15), 150 (10), 136 (3), 70 (45). HRMS Calculated for C17H21C13N2O6: 454.0465. Found: 454.0464. [α]25D=−72.2° (c=0.18, CHCl3).
