p-Toluenesulfonic acid monohydrate → (R)-(+)-methyl 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylate

HRID 1699488Notes

Reaction equation

HRID 1699488 reaction equation
[OH:1][C:2]1[C:3]([CH3:18])=[C:4]([CH3:17])[C:5]2[O:10][C@@:9]([CH3:14])([C:11]([OH:13])=[O:12])[CH2:8][CH2:7][C:6]=2[C:15]=1[CH3:16].O.[C:20]1(C)C=CC(S(O)(=O)=O)=CC=1>CO.O>[OH:1][C:2]1[C:3]([CH3:18])=[C:4]([CH3:17])[C:5]2[O:10][C@@:9]([CH3:14])([C:11]([O:13][CH3:20])=[O:12])[CH2:8][CH2:7][C:6]=2[C:15]=1[CH3:16]

Participants

5

Reactant 2

HCID 521998p-Toluenesulfonic acid monohydrateHCID 65413546-Hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid, (+)-

Product 1

HCID 14308591(R)-(+)-methyl 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylate

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 962WaterSolvent

Procedure

A solution of 2 g (8 mmol) of optically pure (R)-(+)-3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl2 H-1-benzopyran-2-carboxylic acid (1) and 0.1 g of p-toluenesulphonic acid monohydrate in 40 ml methanol were stirred and re-fluxed for 4 hours. After cooling, the solution was diluted with water, extracted three times into ether that was subsequently washed with brine and aqueous sodium bicarbonate solution. The ether solution was washed, dried with MgSO4 and evaporated to give (R)-(+)-methyl 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2 H- 1-benzopyran-2 carboxylate (2).

Workup

  1. temperatureAfter cooling
  2. extractionextracted three times into ether that
  3. washwas subsequently washed with brine and aqueous sodium bicarbonate solution
  4. washThe ether solution was washed
  5. dry with materialdried with MgSO4
  6. customevaporated

Sources & evidence

ORD record
ord-5f5f06c236dd498bbd9f5f3ec01270f3
Source dataset
uspto-grants-2002_02
Patent number
US06346634B1

Reaction notes

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