Synthesis
A mixture of 111.5 g of 7-chloroindole-2-carboxylate in 31.25 g of 96percent sodium hydroxide in 183 ml of methanol and 183 ml of water were heated under reflux for 1 hour, cooled to 45 ° C, and 10 percent hydrochloric acid was added dropwise to a pH of 3 to 4. The mixture was sufficiently cooled to obtain 89.7 g of product as an off-white 7-chloro-1H-indole-2-carboxylic acid.
References
[1] Journal of Medicinal Chemistry, 2003, vol. 46, # 19, p. 3957 - 3960
[2] Patent: CN104402795, 2017, B. Location in patent: Paragraph 0060; 0063
[3] Journal of the Chemical Society, 1955, p. 3499,3502
[4] Patent: US2003/207893, 2003, A1
[5] Patent: WO2004/22061, 2004, A1. Location in patent: Page/Page column 56-57
