Boron tribromide → HCID 13560308, compound

HRID 637729Notes

Reaction equation

HRID 637729 reaction equation
C[O:2][C:3]1[C:4]([CH:13]=[O:14])=[CH:5][C:6]2[O:11][CH2:10][CH2:9][CH2:8][C:7]=2[CH:12]=1.B(Br)(Br)Br>C(Cl)Cl>[OH:2][C:3]1[C:4]([CH:13]=[O:14])=[CH:5][C:6]2[O:11][CH2:10][CH2:9][CH2:8][C:7]=2[CH:12]=1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 10352557HCID 10352557, compound

Product 1

HCID 13560308HCID 13560308, compoundYield 67.6%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Procedure

A solution of 6-methoxy-3,4-dihydrobenzopyran-7-carboxaldehyde (30.00 g, 156 mmol) in dry methylene chloride (625 mL) under nitrogen 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 saturated aqueous sodium chloride (1200 mL). The layers were separated and the organic extract washed with saturated sodium chloride (600 mL), dried (Na2SO4) and concentrated to a dark solid (31.0 g). Purification by preparative HPLC (Waters Prep 500, 9:1 hexane:ethyl acetate as eluant) afforded 6-hydroxy-3,4-dihydrobenzopyran-7-carboxaldehyde (18.80 g, 67.6%), m.p. 97°-100°.

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 saturated 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 to a dark solid (31.0 g)
  9. customPurification by preparative HPLC (Waters Prep 500, 9:1 hexane:ethyl acetate as eluant)

Sources & evidence

ORD record
ord-9c40e516fd304c80b620e78075a047cf
Source dataset
uspto-grants-1985_12
Patent number
US04558067

Reaction notes

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