Dimethylformamide → 6-Methylindole-3-carboxaldehyde

Phosphorus oxychoride (3.2 ml, 34.3 mmol) was added dropwise to dimethyl formamide (26 ml) over ten minutes at ~5° C. To this solution was added a dimethyl formamide (32 ml) solution of 6-methylindole (3.307 g, 25.2 mmol) over 10 minutes. The mixture was slowly warmed to ambient temperature, then heated to 50° C. for four hours. The mixture was cooled to ambient temperature, then poured onto ice (500 g). The aqueous solution was left to stand for 16 hours. Sodium hydroxide (6.0 g) was dissolved in water (22 ml) and added dropwise to the brown solution. The resultant yellow precipitate was boiled and filtered hot. It was left to cool to room temperature, then to 5° C. The precipitate was filtered off and washed with water (800 ml), dried at the pump, then further dried in vacuo at 50° C. for 16 hours to yield a yellow solid.

1. temperatureheated to 50° C. for four hours
2. temperatureThe mixture was cooled to ambient temperature
3. additionpoured onto ice (500 g)
4. waitThe aqueous solution was left
5. additionadded dropwise to the brown solution
6. filtrationfiltered hot
7. waitIt was left
8. temperatureto cool to room temperature
9. customto 5° C
10. filtrationThe precipitate was filtered off
11. washwashed with water (800 ml)
12. customdried at the pump
13. customfurther dried in vacuo at 50° C. for 16 hours
14. customto yield a yellow solid

ORD record

ord-b4086be081a44eb2a170ac9b66d9a69d

Source dataset

uspto-grants-1996_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05563147