Pyruvic Acid → 6-Chloro-5-(ethoxycarbonyl)-1H-indole-2-carboxylic acid

Temperature

100 °C

A solution of ethyl 4-amino-2-chloro-5-iodobenzoate (1.82 g, 5.59 mmol) in N,N-dimethylformamide (18 ml) under argon was admixed with pyruvic acid (1.27 ml, 18.2 mmol) and 1,4-diazabicyclo[2.2.2]octane, evacuated and flooded with argon. Then argon was passed through the solution for 5 min, and then palladium(II) acetate (68 mg, 0.30 mmol) was added and the mixture was heated to 100° C. for 2 h. The cooled solution was filtered through Celite and the filtercake was rinsed with ethyl acetate (100 ml). The filtrate (suspension) was washed with hydrochloric acid (2 M; 2×25 ml) and with water (2×25 ml), dried over sodium sulphate and filtered. The filtrate was concentrated to dryness under reduced pressure and gives a red-brown solid (1.93 g, approx. 51% product), which was used for the next step without further purification.

1. customevacuated
2. filtrationThe cooled solution was filtered through Celite
3. washthe filtercake was rinsed with ethyl acetate (100 ml)
4. washThe filtrate (suspension) was washed with hydrochloric acid (2 M; 2×25 ml) and with water (2×25 ml)
5. dry with materialdried over sodium sulphate
6. filtrationfiltered
7. concentrationThe filtrate was concentrated to dryness under reduced pressure

ORD record

ord-b3117a517844495abd2415846e5cda4d

Source dataset

uspto-grants-2014_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08889878B2