Trimethyl orthoformate → 6-Bromo-5-chlorobenzoxazole

HRID 2272175Notes

Reaction equation

HRID 2272175 reaction equation
[NH2:1][C:2]1[CH:7]=[C:6]([Cl:8])[C:5]([Br:9])=[CH:4][C:3]=1[OH:10].[Yb+3].F[C:13](F)(F)S([O-])(=O)=O.FC(F)(F)S([O-])(=O)=O.FC(F)(F)S([O-])(=O)=O.C(OC)(OC)OC>CCO.CC(=O)OCC.CCCCCC>[Br:9][C:5]1[C:6]([Cl:8])=[CH:7][C:2]2[N:1]=[CH:13][O:10][C:3]=2[CH:4]=1

Participants

7

Reactant 3

HCID 9005Trimethyl orthoformateHCID 2733225Ytterbium triflateHCID 584871002-Amino-5-bromo-4-chlorophenol

Product 1

HCID 584872776-Bromo-5-chlorobenzoxazoleYield 6,559.2%

Reagents, catalysts & solvents 3

HCID 702EthanolSolventHCID 8058HexaneSolventHCID 8857Ethyl AcetateSolvent2×

Conditions

Temperature
90 °C

Procedure

A mixture of 2-amino-5-bromo-4-chlorophenol (29) (865 mg, 3.89 mmol), trifluoromethanesulfonic acid Ytterbium (III) salt (24 mg, 1% mol) and trimethyl orthoformate (511 μl, 1.2 eq.) in 2 ml EtOH was heated at 90° C. for 2 h. After cooling down to r.t., the reaction mixture was taken up in EA, washed with aq. NaHCO3 and brine, dried over Na2SO4, concentrated to dryness. The resulting brown solid was dissolved in DCM and subjected to silica gel column purification using 0-100% B (A: hexane; B: 50% EA in hexane) to furnish 590 mg 30 as yellow solid (yield: 65.2%).

Workup

  1. temperatureAfter cooling down to r.t.
  2. washwashed with aq. NaHCO3 and brine
  3. dry with materialdried over Na2SO4
  4. concentrationconcentrated to dryness
  5. dissolutionThe resulting brown solid was dissolved in DCM
  6. customsubjected to silica gel column purification

Sources & evidence

ORD record
ord-d882ecca016b49c0add45a0487e3ce82
Source dataset
uspto-grants-2015_09
Patent number
US09120751B2

Reaction notes

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