Boron tribromide → 2-(5-Oxazolyl)phenol

HRID 1272193Notes

Reaction equation

HRID 1272193 reaction equation
B(Br)(Br)Br.C[O:6][C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][C:8]=1[C:13]1[O:17][CH:16]=[N:15][CH:14]=1>ClCCl>[O:17]1[C:13]([C:8]2[CH:9]=[CH:10][CH:11]=[CH:12][C:7]=2[OH:6])=[CH:14][N:15]=[CH:16]1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 167406765-(2-Methoxyphenyl)-1,3-oxazole

Product 1

HCID 227234652-(5-Oxazolyl)phenolYield 114.7%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

A mixture of 2-methoxybenzaldehyde (10.0 g, 73.4 mmol), tosylmethylisocyanide (14.34 g, 73.4 mmol) and potassium carbonate (10.14 g, 73.4 mmol) in 220 ml methanol is heated at reflux for 6 hours. The solvent is removed under reduced pressure and the residue poured into ice-water (800 ml). The precipitate is collected by filtration, washed with water, and dried in vacuo to give 9.05 g of 5-(2-methoxyphenyl)oxazole (70%). Boron tribromide (1M in dichloromethane, 36 ml) is added slowly to a cold solution (0° C.) of the above oxazole (3.0 g, 17.1 mmol) in dichloromethane (215 ml). After stirring overnight at room temperature, ice-water (50 ml) is added carefully. The aqueous layer is extracted with dichloromethane (50 ml), and the combined organic layers are dried over sodium sulfate and concentrated under reduced pressure. The precipitate which formed after addition of dichloromethane (70 ml) is collected by filtration, heated with dichloromethane (15 ml), and filtered again to give 3.16 g of 2-(5-oxazolyl)phenol. This phenolic product is reacted with (2S)-glycidyl 3-nitrobenzenesulfonate substantially as described for Epoxide 1 to give 400 mg of the title epoxide (9.5%).

Workup

  1. extractionThe aqueous layer is extracted with dichloromethane (50 ml)
  2. dry with materialthe combined organic layers are dried over sodium sulfate
  3. concentrationconcentrated under reduced pressure
  4. customThe precipitate which formed
  5. filtrationis collected by filtration
  6. temperatureheated with dichloromethane (15 ml)
  7. filtrationfiltered again

Sources & evidence

ORD record
ord-81c28a981c064773830963708faab4ac
Source dataset
uspto-grants-2007_04
Patent number
US07208505B2

Reaction notes

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