4-Ethylbenzoic Acid → Methyl 3-methyl-1H-indole-6-carboxylate

Temperature

130 °C

Methyl 4-ethyl-3-nitrobenzoate (5.0 g), which had been prepared through nitration followed by methyl-esterification of 4-ethylbenzoic acid, is dissolved in N,N-dimethylformamide (50 ml), to which is added N,N-dimethylformamide dimethyl acetal (8.45 g), and stirred under heat at 130° C. for 3 hours. The reaction mixture is concentrated under reduced pressure, and the resulting red oily residue is dissolved in methanol (50 ml), to which is added palladium-carbon (5%, 0.400 g), and stirred in a hydrogen atmosphere at room temperature for 2.5 hours. Then, this is further stirred at 50° C. for 2 hours and thereafter at room temperature for 3 days. The catalyst is removed through filtration, and the filtrate is concentrated under reduced pressure. The resulting residue is recrystallized from t-butyl methyl ether to obtain a pale yellow crystal of the intended product (2.4 g).

1. concentrationThe reaction mixture is concentrated under reduced pressure
2. dissolutionthe resulting red oily residue is dissolved in methanol (50 ml), to which
3. additionis added palladium-carbon (5%, 0.400 g)
4. stirringstirred in a hydrogen atmosphere at room temperature for 2.5 hours
5. stirringThen, this is further stirred at 50° C. for 2 hours
6. customThe catalyst is removed through filtration
7. concentrationthe filtrate is concentrated under reduced pressure
8. customThe resulting residue is recrystallized from t-butyl methyl ether

ORD record

ord-356be7b1a1e84db4bfec2619f722bea0

Source dataset

uspto-grants-2006_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07115647B2