Réaction #923

Équation de réaction

sulfur dioxide

n-butyllithium

N-methyl-pyrrole

t-butylamine

→

title compound

Rendement 28.5%

N-(1,1-Dimethylethyl)-1-methyl-1H-pyrrole-2-sulfonamide

Rendement 28.5%

Solvants

THF

Conditions de réaction

Traitement

1. 1
   Autrethe temperature below -60° C
2. 2
   workup.ADDITIONwas added rapidly
3. 3
   Autreat -20° C.
4. 4
   workup.STIRRINGAfter stirring for 1 h at ambient temperature
5. 5
   Autrethe THF was removed under reduced pressure
6. 6
   AutreThe solids were triturated with ether
7. 7
   Filtrationcollected by filtration with an ether
8. 8
   Lavagerinse
9. 9
   Autrethen dried under nitrogen
10. 10
    workup.ADDITIONThis intermediate sulfinate salt was added to a well
11. 11
    workup.STIRRINGstirred
12. 12
    workup.ADDITIONmixture of 350 mL water and 250 mL dichloromethane
13. 13
    Températurechilled to 0° C
14. 14
    workup.ADDITIONN-Chlorosuccinimide was then added in portions so as
15. 15
    Autrethe temperature below 3° C
16. 16
    workup.STIRRINGThe mixture was stirred vigorously for 30 min at ambient temperature
17. 17
    Autreafter which time, the layers were separated
18. 18
    Lavagethe organic layer was washed successively with 10% aq NaHSO3, twice with aq NaHCO3
19. 19
    Séchagedried (MgSO4)
20. 20
    Filtrationfiltered
21. 21
    TempératureThis dichloromethane solution was then cooled to 0° C.
22. 22
    workup.ADDITIONwas added over 2 min
23. 23
    workup.STIRRINGAfter stirring for 1 h at ambient temperature
24. 24
    Autresolids had precipitated from the brown solution which
25. 25
    workup.WAITwas then left
26. 26
    workup.STIRRINGstirring for 3 days
27. 27
    workup.ADDITIONThe mixture was diluted with more dichloromethane
28. 28
    Lavagethen washed three times with 1N HCl
29. 29
    Séchageonce with saturated aq NaCl, dried (MgSO4)
30. 30
    Autreevaporated
31. 31
    AutreThe resulting solid residue was triturated
32. 32
    Autrecollected with a mixture of hexanes and n-chlorobutane

Mode opératoire

A solution of 10 g (0.12 mol) of N-methyl-pyrrole in 120 mL of anhydrous THF under nitrogen atmosphere was cooled to below -70° C. then treated with 56 mL of 2.4M n-butyllithium in hexanes (0.13 mol) dropwise at such a rate as to keep the temperature below -60° C. The resulting brown colored mixture was stirred for 16 h at ambient temperature, then recooled to below -70° C. at which time liquified sulfur dioxide (9.0 mL, 0.21 mol) was added rapidly, causing an exotherm at -20° C. and the formation of a thick golden colored precipitate. After stirring for 1 h at ambient temperature, the THF was removed under reduced pressure. The solids were triturated with ether and collected by filtration with an ether rinse then dried under nitrogen. This intermediate sulfinate salt was added to a well stirred mixture of 350 mL water and 250 mL dichloromethane chilled to 0° C. N-Chlorosuccinimide was then added in portions so as to keep the temperature below 3° C. The mixture was stirred vigorously for 30 min at ambient temperature, after which time, the layers were separated and the organic layer was washed successively with 10% aq NaHSO3, twice with aq NaHCO3, dried (MgSO4) and filtered. This dichloromethane solution was then cooled to 0° C. and stirred while 82 mL (0.30 mol) of t-butylamine was added over 2 min. After stirring for 1 h at ambient temperature, solids had precipitated from the brown solution which was then left stirring for 3 days. The mixture was diluted with more dichloromethane then washed three times with 1N HCl, once with saturated aq NaCl, dried (MgSO4) and evaporated. The resulting solid residue was triturated and collected with a mixture of hexanes and n-chlorobutane to afford 7.4 g of the title compound as tan crystals, m.p. 125°-126° C.

Source