Lithium iodide → (R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyran

HRID 2253970Notes

Reaction equation

HRID 2253970 reaction equation
C[O:2][C:3]1[CH:19]=[CH:18][C:6]([CH2:7][C@H:8]2[CH2:13][CH2:12][C:11]3[CH:14]=[CH:15][CH:16]=[CH:17][C:10]=3[O:9]2)=[CH:5][CH:4]=1.[I-].[Li+]>N1C(C)=CC(C)=CC=1C.C(OCC)(=O)C.Cl>[OH:2][C:3]1[CH:19]=[CH:18][C:6]([CH2:7][C@H:8]2[CH2:13][CH2:12][C:11]3[CH:14]=[CH:15][CH:16]=[CH:17][C:10]=3[O:9]2)=[CH:5][CH:4]=1

Participants

6

Reactant 2

HCID 66321Lithium iodideHCID 18653186(R)-(-)-3,4-Dihydro-2-(4-methoxybenzyl)-2H-benzopyran

Product 1

HCID 18653185(R)-(-)-3,4-Dihydro-2-(4-hydroxybenzyl)-2H-benzopyranYield 94.9%

Reagents, catalysts & solvents 3

HCID 313Hydrochloric AcidSolventHCID 79532,4,6-TrimethylpyridineSolventHCID 8857Ethyl AcetateSolvent

Procedure

(R)-(-)-3,4-Dihydro-2-(4-methoxybenzyl)-2H-benzopyran (812 mg, 3.2 mmol), and lithium iodide (750 mg, 5.6 mmol) were dissolved in 2,4,6-collidine (2 ml) and heated to reflux for 24 hours. The reaction mixture was cooled, diluted with ethyl acetate (20 ml) and 10% HCl (20 ml), and stirred for 10 minutes. The layers were separated and the aqueous portion was extracted with ethyl acetate (50 ml). The combined organics were washed with water (20 ml), brine (20 ml), and were dried MgSO4). The solvent was removed in vacuo and the residue purified on silica gel using hexanes/ethyl acetate (3:1) as eluent to afford 730 mg of a colorless oil which crystallized upon standing, mp 60°-62° C.; [α]D -110.2° (c 1.0, MeOH); 1H NMR (300 MHz, CDCl3) δ1.7 (m, 1H), 2.0 (m, 1H), 2.7-2.8 (m, 3H), 3.1 (dd, 1H), 4.2 (m, 1H), 6.8 (m, 3H), 7.0-7.2 (m, 4H).

Workup

  1. temperatureheated
  2. temperatureto reflux for 24 hours
  3. temperatureThe reaction mixture was cooled
  4. customThe layers were separated
  5. extractionthe aqueous portion was extracted with ethyl acetate (50 ml)
  6. washThe combined organics were washed with water (20 ml), brine (20 ml)
  7. customThe solvent was removed in vacuo
  8. customthe residue purified on silica gel

Sources & evidence

ORD record
ord-5c52dd84d0db461c968a44af1f0a8074
Source dataset
uspto-grants-1993_08
Patent number
US05232945

Reaction notes

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