Trimethyl orthoformate → 6-Bromo-5-chlorobenzoxazole

HRID 1036078Notes

Reaction equation

HRID 1036078 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 65.2%

Reagents, catalysts & solvents 3

HCID 702EthanolSolventHCID 8058HexaneSolventHCID 8857Ethyl AcetateSolvent2×

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

Sources & evidence

ORD record
ord-f9bf62325b3042e2a61c384075780223
Source dataset
uspto-grants-2013_10
Patent number
US08546403B2

Reaction notes

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