Sulfur Dioxide → HCID 23716504, compound

HRID 2081813Notes

Reaction equation

HRID 2081813 reaction equation
C([Li])CCC.[CH3:6][C:7]1([CH3:18])[CH:16]=[CH:15][C:14]2[C:9](=[CH:10][CH:11]=[C:12](Br)[CH:13]=2)[O:8]1.[S:19](=[O:21])=[O:20].[Li].C[O-].[Na+:25]>CCCCCC.[Na]>[CH3:6][C:7]1([CH3:18])[CH:16]=[CH:15][C:14]2[C:9](=[CH:10][CH:11]=[C:12]([S:19]([O-:21])=[O:20])[CH:13]=2)[O:8]1.[Na+:25]

Participants

8

Reactant 5

HCID 1119Sulfur DioxideHCID 3028194LithiumHCID 10942334Sodium MethoxideHCID 117705336-Bromo-2,2-dimethyl-2H-chromeneHCID 178418339Butyllithium

Product 1

HCID 23716504HCID 23716504, compound

Reagents, catalysts & solvents 2

HCID 8058HexaneSolventHCID 5360545SodiumSolvent

Conditions

Temperature
-20 °C

Procedure

A 1.5M solution of butyllithium in hexane (5.2 ml) was added to a stirred solution of 2,2-dimethyl-6-bromochromene [prepared by the procedure described in Bull. Chem. Soc. Jap., 1982, 55(4) 1153] (2.0 g, 8.4 mM) in sodium dried ether (24 ml). The mixture was stirred for 3 hours, then cooled to -20° C. and treated with excess gaseous sulphur dioxide, whereupon the lithium sulphinate salt immediately began to separate out as a solid. The resultant suspension was stirred rapidly for one hour and then allowed to attain ambient temperature. The solid precipitate of lithium 2,2-dimethylchromene-6-sulphinate was collected by filtration and washed with dry acetone and sodium dried ether. The lithium salt was then dissolved in water and the solution acidified to pH 1 and extracted with ethyl acetate. The combined extracts were dried (Na2SO4) and evaporated. The resultant 2,2-dimethylchromene-6-sulphinic acid was dissolved in methanol (10 ml) containing sodium methoxide (400 mg, 7.3 mmol). After 10 minutes, the methanol was removed in vacuo to leave a solid residue of sodium 2,2-dimethylchromene-6-sulphinate, which was dried by azeotropic distillation with toluene in vacuo and used directly in the above reaction.

Workup

  1. customprepared by the procedure
  2. customto separate out as a solid
  3. stirringThe resultant suspension was stirred rapidly for one hour
  4. customto attain ambient temperature
  5. filtrationThe solid precipitate of lithium 2,2-dimethylchromene-6-sulphinate was collected by filtration
  6. washwashed with dry acetone and sodium dried ether
  7. dissolutionThe lithium salt was then dissolved in water
  8. extractionextracted with ethyl acetate
  9. dry with materialThe combined extracts were dried (Na2SO4)
  10. customevaporated
  11. dissolutionThe resultant 2,2-dimethylchromene-6-sulphinic acid was dissolved in methanol (10 ml)
  12. waitAfter 10 minutes
  13. customthe methanol was removed in vacuo

Sources & evidence

ORD record
ord-d86012ffc6b94bd0a83781f038fec8c0
Source dataset
uspto-grants-1993_02
Patent number
US05185452

Reaction notes

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