Hydrochloric Acid → racemic-3,4-dihydro-7-(phenylmethoxy)-2H-1-benzopyran-2-carboxaldehyde

HRID 2232498Notes

Reaction equation

HRID 2232498 reaction equation
C([O:3][C:4]([CH:6]1[CH2:11][CH2:10][C:9]2[CH:12]=[CH:13][C:14]([O:16][CH2:17][C:18]3[CH:23]=[CH:22][CH:21]=[CH:20][CH:19]=3)=[CH:15][C:8]=2[O:7]1)=O)C.C(=O)=O.CC(C)=O.[H-].C([Al+]CC(C)C)C(C)C.Cl>C1(C)C=CC=CC=1.CO>[C:18]1([CH2:17][O:16][C:14]2[CH:13]=[CH:12][C:9]3[CH2:10][CH2:11][CH:6]([CH:4]=[O:3])[O:7][C:8]=3[CH:15]=2)[CH:19]=[CH:20][CH:21]=[CH:22][CH:23]=1

Participants

7

Reactant 4

HCID 313Hydrochloric AcidHCID 11162736Ethyl 7-(Benzyloxy)chroman-2-carboxylateHCID 18522661Acetone cardiceHCID 21225700Diisobutylaluminumhydride

Product 1

HCID 14541228racemic-3,4-dihydro-7-(phenylmethoxy)-2H-1-benzopyran-2-carboxaldehydeYield 94.9%

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 1140TolueneSolvent2×

Procedure

The ether ester product from example 82 (6.9 g, 22 mmoles) was dissolved in 70 ml of toluene and the solution was cooled to -78° C. (dry-ice-acetone bath). With stirring, 15.6 ml of a 25% solution of diisobutylaluminum hydride in toluene was added dropwise. The reaction mixture was stirred at -78° C. for 2 hours whereupon 2.5 ml of methanol was cautiously added followed by 2N HCl and ice. The mixture was extracted with ethyl acetate and the organic extracts were combined, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure. The residue (7.6 g) was chromatographed on silica gel. Elution with 9:1 toluene-ethyl acetate gave 5.6 g (70%) of racemic-3,4-dihydro-7-(phenylmethoxy)-2H-1-benzopyran-2-carboxaldehyde as a pale yellow oil.

Workup

  1. additionwas cautiously added
  2. extractionThe mixture was extracted with ethyl acetate
  3. washwashed with saturated brine
  4. dry with materialdried over anhydrous magnesium sulfate
  5. filtrationfiltered
  6. concentrationconcentrated under reduced pressure
  7. customThe residue (7.6 g) was chromatographed on silica gel
  8. washElution with 9:1 toluene-ethyl acetate

Sources & evidence

ORD record
ord-23ee7dc64d554386955d905acedee01e
Source dataset
uspto-grants-1988_11
Patent number
US04788214

Reaction notes

Loading…