Oxalyl chloride → Ethyl 6-chloro-7-(4-(2,4-dichlorophenethylcarbamoyl)phenoxy)chroman-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

4-(6-Chloro-4-(ethoxycarbonyl)chroman-7-yloxy)benzoic acid was dissolved in 700 mL of dichloromethane containing 8 drops of DMF and cooled to 5° C. Oxalyl chloride (31 mL, 355 mmol) was added as a solution in 10 mL of dichloromethane dropwise over 20 minutes keeping the reaction temperature between 8 and 11° C. After stirring at ambient temperature for 20 hours, the solution was cooled to 0° C. and 2,4-dichlorophenethyl amine (55 mL, 365 mmol) was added as a solution in 20 mL of dichloromethane dropwise over 20 minutes keeping the reaction temperature below 10° C. To the resulting thick, cream-colored slurry was added diisopropyl ethyl amine (70 mL, 402 mmol) dropwise over 20 minutes keeping the reaction temperature below 10° C. After 3 hours at ambient temperature, the reaction mixture was diluted with 2 L of dichloromethane and washed sequentially with three 500 mL portions of 1 N HCl, two 500 mL portions of water and two 500 mL portions of brine. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to give 178 g of crude ethyl 6-chloro-7-(4-(2,4-dichlorophenethylcarbamoyl)phenoxy)chroman-4-carboxylate. The crude material was slurried in hot ethyl acetate, cooled to ambient temperature and the solids were collected, washing with 20% ethyl acetate in hexanes. The white solids were dried under high vacuum to give ethyl 6-chloro-7-(4-(2,4-dichlorophenethyl-carbamoyl)phenoxy)chroman-4-carboxylate (145 g, 80% yield). 1H NMR (400 MHz, CDCl3) δ 7.68 (d, J=8.4 Hz, 2H), 7.40 (s, 1H), 7.36 (s, 1H), 7.20 (s, 2H), 6.96 (d, J=8.6 Hz, 2H), 6.53 (s, 1H), 6.12 (t, J=5.3 Hz, 1H), 4.21-4.29 (m, 4H), 3.67-3.75 (m, 3H), 3.05 (t, J=6.7 Hz, 2H), 2.30-2.35 (m, 1H), 2.05-2.14 (m, 1H), 1.31 (t, J=7.0 Hz, 3H).

Provenance & Evidence