2-Methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic acid → 2-Methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic anhydride

HRID 1655877Notes

Reaction equation

HRID 1655877 reaction equation
[CH3:1][C:2]1[O:3][C:4]2[C:9]([N:10]=1)=[CH:8][C:7]([C:11]([OH:13])=O)=[C:6]([C:14]([OH:16])=[O:15])[N:5]=2>C(OC(=O)C)(=O)C>[CH3:1][C:2]1[O:3][C:4]2[C:9]([N:10]=1)=[CH:8][C:7]1[C:11]([O:16][C:14](=[O:15])[C:6]=1[N:5]=2)=[O:13]

Participants

3

Reactant 1

HCID 199581932-Methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic acid

Product 1

HCID 153898982-Methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic anhydrideYield 97%

Reagents, catalysts & solvents 1

HCID 7918Acetic AnhydrideSolvent

Conditions

Temperature
70 °C

Procedure

A suspension of 2-methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic acid (4.84 g, 0.0218 mol) in acetic anhydride (150 mL) is slowly heated to 70° C. at which point all the solids dissolve forming a yellow solution. The reaction mixture is heated at 70° C. overnight, cooled to room temperature, and concentrated in vacuo. Xylene is added to remove excess acetic anhydride by codistillation. 2-Methyloxazolo[5,4-b]pyridine-5,6-dicarboxylic anhydride is obtained as a pale yellow solid in 97% yield melting point 194°-196° C.

Workup

  1. dissolutiondissolve
  2. customforming a yellow solution
  3. temperatureThe reaction mixture is heated at 70° C. overnight
  4. temperaturecooled to room temperature
  5. concentrationconcentrated in vacuo
  6. additionXylene is added
  7. customto remove excess acetic anhydride by codistillation

Sources & evidence

ORD record
ord-7974c6c1ef1b4a53a83292e222c8f104
Source dataset
uspto-grants-1993_10
Patent number
US05252538

Reaction notes

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