Synthesis
General procedure for the synthesis of 1-indolepropionic acid from indole and methyl 3-bromopropionate: Synthesis of 3-(1H-indol-1-yl)propionic acid (Intermediate-25): 10 mL of DMF was added to a 100 mL round bottom flask fitted with a magnetic stirrer. to the stirred solvent was added indole (1.0 g, 8.53 mmol) followed by sodium hydride (400 mg, 10.24 mmol). The resulting mixture was stirred at room temperature for 1 hr. Methyl 3-bromopropionate (2.13 g, 12.79 mmol) was added to the above reaction solution and stirring was continued for 24 hours at room temperature. After completion of the reaction (the progress of the reaction was monitored by TLC), the reaction mixture was diluted with 30 mL of ice water and washed with ether. The aqueous phase was acidified with 1N HCl to pH=2 and subsequently extracted with EtOAc and concentrated to give Intermediate-24 (900 mg).
References
[1] Patent: WO2013/128465, 2013, A1. Location in patent: Page/Page column 94
[2] Patent: US2015/158860, 2015, A1. Location in patent: Paragraph 0332
[3] Patent: WO2004/43899, 2004, A1. Location in patent: Page 37; 38
