7-Methoxy-1H-indole-2,3-dione is one of the key intermediates of the EP3 receptor, which has a variety of biological functions, including digestion, the nervous system, renal reabsorption, uterine contraction activity, and inhibition of gastric acid secretion.
7-Methoxyisatin is synthesized in four steps. a) 4-Hydroxybenzaldehyde reacts with methyl iodide in DMSO and K2CO3 to give 4-methoxybenzaldehyde. b) 4-Methoxybenzaldehyde reacts with methyl azidoacetate in sodium methoxide/methanol to yield an azide intermediate. This intermediate is refluxed in boiling xylene to give methyl 6-methoxyindole-2-carboxylate. c) This ester is saponified by refluxing with NaOH/methanol. Acidification yields 6-methoxyindole-2-carboxylic acid. d) This acid reacts with ethyl N,N-dichlorocarbamate in aqueous acetic acid. Work-up gives 7-methoxy-1H-indole-2,3-dione.
