Acetic acid, 2-(triphenylphosphoranylidene)-, methyl ester → 5-Acetamino-2-indoleacrylic acid

Participants

Reaction Steps

16 (340 mg, 0.7 mmol) was added to a solution of methyl(triphenylphosphoranylidene)acetate (2|57 mg, 0.77 mmol) in toluene (30 mL) and the reaction mixture was heated to reflux for 3 days. The solvent was removed after cooled to room temperature. Ethyl acetate (10 mL) was added to the residue and the resulted precipitate 17 was filtered. MS (ion spray) (M+H) 259. Without further purification 17 was dissolved in DMF (3 mL) and methanol (5 mL) was added. 3N NaOH solution (2 mL) was added and the reaction mixture was stirred overnight. The solvent was removed and water (10 mL) was added. The solution was neutralized using 20% HCl. The resulting precipitate was filtered and washed with water. 44 mg (26% yield) of yellow solid 18 was obtained. mp: 238°-239° C. 1H NMR (DMSO-d6, ppm): 12.25 (brs, 1 H, COOH), 11.42 (s, 1 H, NH), 9.74 (s, 1 H, NH), 7.88 (s, 1 H, Ar--H), 7.55-7.50 (d, 1 H, J=16.0 Hz, CH=CH), 7.28 (s, 2 H, Ar--H) 6.80 (d, 1 H, J=2.0 Hz, Ar--H), 6.44-6.40 (d, 1 H, J=15.8 Hz, CH=CH), 2.03 (s, 3 H, CH3), Anal. (C13H12N2O3 0.3H2O), C, H, N.

Provenance & Evidence