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Full structural formula Skeletal formula with numbers
Ball-and-stick model Space-filling model
CAS number 288-42-6 YesY
PubChem 9255
ChemSpider 8898 N
EC number 206-020-8
MeSH D010080
Jmol-3D images Image 1
Molecular formula C3H3NO
Molar mass 69.06 g mol−1
Density 1.050 g/cm3
Boiling point 69 to 70 °C (156 to 158 °F; 342 to 343 K)
Acidity (pKa) 0.8 (of conjugate acid) [1]
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon.[2] Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a pKa of 0.8, compared to 7 for imidazole.


Classical oxazole synthetic methods in organic chemistry are

Other methods are reported in literature.

oxazoline from propargyl amides Merkul 2006
Oxazoline Synthesis Continuous Reactor


In biomolecules, oxazoles result from the cyclization and oxidation of serine or threonine nonribosomal peptides:

Where X = H, CH
for serine and threonine respectively, B = base.
(1) Enzymatic cyclization. (2) Elimination. (3) [O] = enzymatic oxidation.

Oxazoles are not as abundant in biomolecules as the related thiazoles with oxygen replaced by a sulfur atom.


Oxazoline CAN oxidation
In the balanced half-reaction three equivalents of water are consumed for each equivalent of oxazoline, generating 4 protons and 4 electrons (the latter derived from CeIV).

See also[edit]


  1. ^ Zoltewicz, J. A. & Deady, L. W. Quaternization of heteroaromatic compounds. Quantitative aspects. Adv. Heterocycl. Chem. 22, 71-121 (1978).
  2. ^ Heterocyclic Chemistry TL Gilchrist, The Bath press 1985 ISBN 0-582-01421-2
  3. ^ A new consecutive three-component oxazole synthesis by an amidation–coupling–cycloisomerization (ACCI) sequence Eugen Merkul and Thomas J. J. Müller Chem. Commun., 2006, 4817 - 4819, doi:10.1039/b610839c
  4. ^ Fully Automated Continuous Flow Synthesis of 4,5-Disubstituted Oxazoles Marcus Baumann, Ian R. Baxendale, Steven V. Ley, Christoper D. Smith, and Geoffrey K. Tranmer Org. Lett.; 2006; 8(23) pp 5231 - 5234; (Letter) doi:10.1021/ol061975c
  5. ^ They react together in the first phase in a continuous flow reactor to the intermediate enol and then in the second phase in a phosphazene base (PS-BEMP) induced cyclization by solid-phase synthesis.
  6. ^ Ceric Ammonium Nitrate Promoted Oxidation of Oxazoles David A. Evans, Pavel Nagorny, and Risheng Xu Org. Lett.; 2006; 8(24) pp 5669 - 5671; (Letter) doi:10.1021/ol0624530