3,4-dihydro-2H-1-benzopyran-2-carboxylic acid → (R)-chroman-2-carboxylic acid

HRID 2298794Notes

Reaction equation

HRID 2298794 reaction equation
[O:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[CH2:4][CH2:3][CH:2]1[C:11]([OH:13])=[O:12]>C(O)C>[O:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[CH2:4][CH2:3][C@@H:2]1[C:11]([OH:13])=[O:12]

Participants

3

Reactant 1

HCID 27236653,4-dihydro-2H-1-benzopyran-2-carboxylic acid

Product 1

HCID 6933107(R)-chroman-2-carboxylic acidYield 13.4%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent2×

Procedure

A solution of (+)-(R)-α-methylbelnzylamine (0.37 mol) in ethanol (100 ml) was added to a solution of 3,4-dihydro-2H-1-benzopyran-2-carboxylic acid (0.36 mol) in ethanol (200 ml). The mixture was allowed to crystallize out. The precipitate was filtered off and dried. The residue was crystallized 4 times from ethanol. The precipitate was filtered off and dried. The residue was taken up in water, treated with HCl 10% and extracted with diethyl ether. The organic layer was separated, dried, filtered and the solvent was evaporated, yielding 8.6 g of (−)-(R)-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid (mp. 85.5° C., [α]D20=−6.7° (c=100 mg/10 ml in methanol)) (interm. 1).

Workup

  1. customto crystallize out
  2. filtrationThe precipitate was filtered off
  3. customdried
  4. customThe residue was crystallized 4 times from ethanol
  5. filtrationThe precipitate was filtered off
  6. customdried
  7. additiontreated with HCl 10%
  8. extractionextracted with diethyl ether
  9. customThe organic layer was separated
  10. customdried
  11. filtrationfiltered
  12. customthe solvent was evaporated

Sources & evidence

ORD record
ord-1a9c1139e145451397779da8ca8012d7
Source dataset
uspto-grants-2002_12
Patent number
US06495547B1

Reaction notes

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