Thionyl Chloride → 2,5-Dichlorobenzooxazole

HRID 512443Notes

Reaction equation

HRID 512443 reaction equation
[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[O:9][C:8](S)=[N:7][C:6]=2[CH:11]=1.S(Cl)([Cl:14])=O>CN(C=O)C>[Cl:14][C:8]1[O:9][C:5]2[CH:4]=[CH:3][C:2]([Cl:1])=[CH:11][C:6]=2[N:7]=1

Participants

4

Reactant 2

HCID 24386Thionyl ChlorideHCID 178527795HCID 178527795, compound

Product 1

HCID 103975782,5-Dichlorobenzooxazole

Reagents, catalysts & solvents 1

HCID 6228DimethylformamideSolvent

Conditions

Temperature
65 °C

Procedure

Subsequently, 5-chloro-2-mercaptobenzoxazole (3.1 g, 16.7 mmol) was dissolved in thionyl chloride (30 mL, 413 mmol). DMF (1.5 mL) was added and the reaction mixture was heated at 65° C. for 45 min. The solvent was removed under reduced pressure and to the residue was added toluene (2×60 mL) followed by evaporation each time to remove the excess SOCl2 (azetrope). The resultant crude product was dissolved in ethyl acetate (100 mL), washed with water (100 mL) and dried over Na2SO4. Evaporation of ethyl acetate gave 2,5-dichlorobenzoxazole, compound 19, as a red oil (3.2 g).

Workup

  1. customThe solvent was removed under reduced pressure and to the residue
  2. additionwas added toluene (2×60 mL)
  3. customfollowed by evaporation each time
  4. customto remove the excess SOCl2 (azetrope)
  5. dissolutionThe resultant crude product was dissolved in ethyl acetate (100 mL)
  6. washwashed with water (100 mL)
  7. dry with materialdried over Na2SO4
  8. customEvaporation of ethyl acetate

Sources & evidence

ORD record
ord-ca1400236bfc4963980294c0d2c3095d
Source dataset
uspto-grants-2015_08
Patent number
US09102636B2

Reaction notes

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