Reaction #5331

Reaction equation

Methyl 3,4-diamino-5-methylthiophene-2-carboxylate

triphosgene

→

title compound

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

Solvents

N,N-dimethyl formamide

dichloromethane

Conditions

Workup

1. 1
   Otherprecipitates
2. 2
   Filtrationwere collected by filtration
3. 3
   Washwashed with dichloromethane
4. 4
   Otherdried
5. 5
   workup.ADDITIONTo the suspension was added sodium hydride (60% in oil; 0.55 g)
6. 6
   workup.STIRRINGthe mixture was stirred for three days at room temperature
7. 7
   OtherThe solvent was evaporated under reduced pressure
8. 8
   workup.ADDITIONTo the residue was added 2N-HCl
9. 9
   OtherResulting
10. 10
    Otherprecipitates
11. 11
    Filtrationwere collected by filtration
12. 12
    Washwashed with water, ether and methanol successively
13. 13
    Otherby drying

Procedure

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.

Source