Acetohydrazide → 3-methyl-6,7-dihydro-5H-pyrrolo[2,1-c][1,2,4]triazole-7-carboxylic acid

Dissolved commercially available ethyl 2-oxopyrrolidine-3-carboxylate (2.50 g, 15.9 mmol) in 30 ml dichloromethane in 50 ml round bottom flask. To this solution was added trimethyloxonium tetrafluoroborate (2.59 g, 17.5 mmol) as a solid and rinsed in with 20 ml dichloromethane. The resulting mixture was stirred at room temperature for 2 h. Acetohydrazide (1.18 g, 15.9 mmol) was introduced as a solid to the mixture and the resulting solution was stirred at room temperature for 3 h. The solution was then concentrated under vacuum to remove all dichloromethane and the residue was then taken up in 100 ml n-butanol which was heated to reflux in an oil bath set at 120° C. overnight. The solution was cooled to room temperature and concentrated under vacuum. The residue was purified silica gel chromatography eluting with 10% dichloromethane: in methanol to afford the title compound (454 mg, 11%). 1H NMR (500 MHz DMSO-d6) δ; 4.16-4.06 (m, 1H), 4.00-3.88 (m, 1H), 2.85-2.78 (m, 1H), 2.29 (s, 3H), 1.55 (dt, J=6.7, 13.9 Hz, 2H), 1.32 (dt, J=6.7, 14.0 Hz, 2H), 0.88 (t, J=7.5 Hz, 3H). LC-MS: m/z (ES)=196 (MH)+.

1. washrinsed in with 20 ml dichloromethane
2. stirringthe resulting solution was stirred at room temperature for 3 h
3. concentrationThe solution was then concentrated under vacuum
4. customto remove all dichloromethane
5. temperaturewas heated
6. temperatureto reflux in an oil bath
7. waitset at 120° C. overnight
8. temperatureThe solution was cooled to room temperature
9. concentrationconcentrated under vacuum
10. customThe residue was purified silica gel chromatography
11. washeluting with 10% dichloromethane

ORD record

ord-9ff177d4bf5646d48ddb6d859695a6ff

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08501786B2