Hydrochloric Acid → 4-(2-oxo-2,3-dihydro-1H-indol-3-yl)butanoic acid

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Reaction Steps

Concentrated HCl (16.6 mL) was added dropwise with stirring, over 10 minutes, to a solution of 4-(3-indolyl)butanoic acid [II: R1 =R3 =H, R2 =(CH2)3COOH] (2.00 g) in DMSO (7.0 mL) at room temperature (method of Savige WE, Fontana A, J. Chem. Soc. Chem. Commun. 1976:599). After 15 minutes reaction, the mixture was diluted with water (80 mL) and extracted with EtOAc (4×100 mL). Removal of the solvent gave crude 4-(2-oxo-3-indolinyl)butanoic acid [III: R1 =R3 =H, R2 =(CH2)3COOH] (2.07 g, 96%) as a green-brown solid; mp (water) 169°-171° C. (Hinman RL, Bauman CP, J. Org. Chem, 1964;29:1206 record mp 170°-171° C.).

Provenance & Evidence