Reaction #919

Reaction equation

N-chlorosuccinimide

n-butyllithium

N-(1,1-dimethylethyl)-1-methyl-1H-pyrrole-3-sulfonamide

tetrahydrofuran

sulfur dioxide

→

title compound

(1,1-Dimethylethyl)-N2,N2,1-trimethyl-1H-pyrrole-2,3-disulfonamide

Solvents

Conditions

Workup

1. 1
   OtherThe colorless reaction
2. 2
   Otherthe temperature below -65° C
3. 3
   workup.ADDITIONwas added (180 mmol)
4. 4
   OtherThe THF was removed under reduced pressure
5. 5
   workup.DISSOLUTIONThe residue was dissolved in 150 mL glacial acetic acid
6. 6
   Temperaturecooled to 20° C.
7. 7
   OtherAfter ca. 1 hour at room temperature the acetic acid was evaporated at reduced pressure
8. 8
   workup.DISSOLUTIONthe residue was dissolved in ethyl acetate
9. 9
   WashThis solution was washed successively with water, NaHCO3 solution, brine
10. 10
    Dryingdried (MgSO4)
11. 11
    Otherevaporated invacuo
12. 12
    workup.DISSOLUTIONThe residue was dissolved in methylene chloride (150 mL)
13. 13
    Temperaturecooled to -20° C.
14. 14
    Temperatureto warm to room temperature
15. 15
    workup.STIRRINGstir overnight ca. 16 hours
16. 16
    WashThe solution was washed with 1N HCl
17. 17
    Dryingdried (MgSO4)
18. 18
    Otherevaporated
19. 19
    workup.DISSOLUTIONThe crude material was dissolved in acetonitrile
20. 20
    workup.ADDITIONtreated with activated charcoal
21. 21
    Filtrationfiltered
22. 22
    Concentrationconcentrated
23. 23
    OtherThe residue was triturated with hexanes/n-butyl chloride

Procedure

A solution of 6.48 g (30 mmol) of N-(1,1-dimethylethyl)-1-methyl-1H-pyrrole-3-sulfonamide in 150 mL of anhydrous tetrahydrofuran (THF) under nitrogen atmosphere was cooled to -78° C. The colorless reaction was treated with 61.5 mmol of 2.38M n-butyllithium in hexanes dropwise at such a rate as to keep the temperature below -65° C. After ca. 1 hour at -78° C., liquified sulfur dioxide was added (180 mmol). The amber solution was warmed to room temperature and stirred for ca. 1 hour. The THF was removed under reduced pressure. The residue was dissolved in 150 mL glacial acetic acid, cooled to 20° C. and then treated with 31 mmol of N-chlorosuccinimide. After ca. 1 hour at room temperature the acetic acid was evaporated at reduced pressure and the residue was dissolved in ethyl acetate. This solution was washed successively with water, NaHCO3 solution, brine, dried (MgSO4) and evaporated invacuo. The residue was dissolved in methylene chloride (150 mL), cooled to -20° C. and treated with 75 mmol of liquefied dimethylimine. The reaction mixture was allowed to warm to room temperature and stir overnight ca. 16 hours. The solution was washed with 1N HCl, dried (MgSO4) and evaporated. The crude material was dissolved in acetonitrile and treated with activated charcoal, filtered and concentrated. The residue was triturated with hexanes/n-butyl chloride to yield 6.95 g of the title compound as a light brown solid, m.p. 98°-101° C.

Source