Triphosgene → Methyl 1,3-dihydro-4-methyl-2-oxo-thieno[3,4-d]imidazole-6-carboxylate

Methyl 3,4-diamino-5-methylthiophene-2-carboxylate (3.0 g) was dissolved in a mixture of N,N-dimethyl formamide (5 ml) and dichloromethane (15 ml). To the solution was added triphosgene (2.4 g) in portions. The mixture was stirred for two days at room temperature, and precipitates were collected by filtration, washed with dichloromethane and dried. Resultant white powder (2.4 g) was suspended in N,N-dimethylformamide (25 ml). To the suspension was added sodium hydride (60% in oil; 0.55 g), and the mixture was stirred for three days at room temperature. The solvent was evaporated under reduced pressure. To the residue was added 2N-HCl. Resulting precipitates were collected by filtration, washed with water, ether and methanol successively, followed by drying to afford the title compound (82 g, 53%) as pale brown powder.

1. customprecipitates
2. filtrationwere collected by filtration
3. washwashed with dichloromethane
4. customdried
5. additionTo the suspension was added sodium hydride (60% in oil; 0.55 g)
6. stirringthe mixture was stirred for three days at room temperature
7. customThe solvent was evaporated under reduced pressure
8. additionTo the residue was added 2N-HCl
9. customResulting
10. customprecipitates
11. filtrationwere collected by filtration
12. washwashed with water, ether and methanol successively
13. customby drying

ORD record

ord-d1f8bbd3082843679aac7401c460d216

Source dataset

uspto-grants-1998_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05736555