Cerium(III) chloride → 2H,8H-Benzo[1,2-b:3,4-b′]dipyran-2-one, 9,10-dihydro-5,10-dihydroxy-8,9-dimethyl-4-propyl-

HRID 433966Notes

Reaction equation

HRID 433966 reaction equation
[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6](=[O:14])[CH:7]([CH3:13])[CH:8]([CH3:12])[O:9]2)=[C:4]2[O:15][C:16](=[O:22])[CH:17]=[C:18]([CH2:19][CH2:20][CH3:21])[C:3]=12.[Cl-].[Ce+3].[Cl-].[Cl-].[BH4-].[Na+]>CO>[OH:1][C:2]1[CH:11]=[C:10]2[C:5]([CH:6]([OH:14])[CH:7]([CH3:13])[CH:8]([CH3:12])[O:9]2)=[C:4]2[O:15][C:16](=[O:22])[CH:17]=[C:18]([CH2:19][CH2:20][CH3:21])[C:3]=12

Participants

5

Reactant 3

HCID 24636Cerium(III) chlorideHCID 4311764Sodium borohydrideHCID 11033986HCID 11033986, compound

Product 1

HCID 187563942H,8H-Benzo[1,2-b:3,4-b′]dipyran-2-one, 9,10-dihydro-5,10-dihydroxy-8,9-dimethyl-4-propyl-Yield 98%

Reagents, catalysts & solvents 1

HCID 887MethanolSolvent

Conditions

Temperature
0 °C

Procedure

A solution of 5-hydroxy-8,9-dimethyl-4-propyl-8,9-dihydro-pyrano[2,3-f]chromene-2,10-dione (a mixture of cis- and trans-37a) (2 g, 6.61 mmol, 1.00 eq) and cerium(III) chloride septahydrate (2.5 g, 6.71 mol, 1.02 eq) in methanol (300 mL) was cooled to 0° C. Sodium borohydride (0.62 g, 16.39 mmol, 2.48 eq) was added portionwise to the stirred solution within 1 h while the temp was maintained at 0-5° C. The reaction mixture was allowed to warm up to room temperature and stirring continued for 2 h. Solvent was removed under vacuum and the residue partitioned between dichloromethane (200 mL) and ice-cold 1N hydrochloric acid (100 mL). The organic layer was separated, washed successively with saturated solution of sodium bicarbonate (200 mL) and brine (200 mL). The organic layer was dried over anhydrous sodium sulfate and concentrated under vacuum yielding 1.97 g (98%) of a mixture of cis- and trans-17a. The crude product was used for the next step without further purification.

Workup

  1. temperaturewas maintained at 0-5° C
  2. temperatureto warm up to room temperature
  3. customSolvent was removed under vacuum
  4. customthe residue partitioned between dichloromethane (200 mL) and ice-cold 1N hydrochloric acid (100 mL)
  5. customThe organic layer was separated
  6. washwashed successively with saturated solution of sodium bicarbonate (200 mL) and brine (200 mL)
  7. dry with materialThe organic layer was dried over anhydrous sodium sulfate
  8. concentrationconcentrated under vacuum

Sources & evidence

ORD record
ord-dc6648b7e69c4efc8e8027641b77d211
Source dataset
uspto-grants-2003_12
Patent number
US06670383B2

Reaction notes

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