Boron tribromide → HCID 13564460, compound

HRID 1284555Notes

Reaction equation

HRID 1284555 reaction equation
C[O:2][C:3]1[C:12]([CH:13]=[O:14])=[C:7]2[CH2:8][CH2:9][CH2:10][O:11][C:6]2=[CH:5][CH:4]=1.B(Br)(Br)Br>C(Cl)Cl>[OH:2][C:3]1[C:12]([CH:13]=[O:14])=[C:7]2[CH2:8][CH2:9][CH2:10][O:11][C:6]2=[CH:5][CH:4]=1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 10397697HCID 10397697, compound

Product 1

HCID 13564460HCID 13564460, compoundYield 80.8%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of 6-methoxy-3,4-dihydrobenzopyran-5-carboxaldehyde (30.00 g, 156 mmol) in dry methylene chloride (625 mL) was cooled to an internal temperature of -67°. A solution of boron tribromide (1M in methylene chloride, 67.5 mL, 67.5 mmol) was added dropwise. The cooling bath was removed and the mixture allowed to stir under nitrogen for three hours. The reaction was then quenched by the dropwise addition of methanol (75 mL) and the resulting mixture poured into satureated aqueous sodium chloride (1200 mL). The layers were separated and the organic extract washed with saturated sodium chloride (600 mL), dried (Na2SO4) and concentrated. Purification by preparative HPLC (Waters Prep 500, 9:1 hexane: ethyl acetate as eluant) afforded 6-hydroxy-3,4-dihydrobenzopyran-5 -carboxaldehyde (22.46 g, 80.8%), m.p. 93-95.

Workup

  1. customThe cooling bath was removed
  2. customThe reaction was then quenched by the dropwise addition of methanol (75 mL)
  3. additionthe resulting mixture poured into satureated aqueous sodium chloride (1200 mL)
  4. customThe layers were separated
  5. extractionthe organic extract
  6. washwashed with saturated sodium chloride (600 mL)
  7. dry with materialdried (Na2SO4)
  8. concentrationconcentrated
  9. customPurification by preparative HPLC (Waters Prep 500, 9:1 hexane: ethyl acetate as eluant)

Sources & evidence

ORD record
ord-95def54f95774bc49e15570fb2ceeccb
Source dataset
uspto-grants-1986_01
Patent number
US04563476

Reaction notes

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