Acyl azide

Preparation

Typically acyl azides are generated under conditions where they rearrange to the isocyanate.

Acid chlorides and anhydrides react with sodium azide or trimethylsilyl azide to give acyl azides: :[[File:Preparation of acyl azides from acyl chlorides.png|300px]] In a Mitsunobu variant, triphenylphosphine and trichloroacetonitrile catalyze excellent yields from various carboxylic acids and sodium azide at mild conditions.

The second major route to azides is from treating acylhydrazines with nitrous acid. Alternatively, the acyl azide can be formed by the direct reaction of a carboxylic acid with diphenylphosphoryl azide (DPPA).

Another route oxidizes aldehydes with iodine azide, formed from sodium azide and iodine monochloride in acetonitrile.

Uses

On Curtius rearrangement, acyl azides yield isocyanates.

:[[File:Curtius Rearrangement Scheme.png|300px]]

Acyl azides are also formed in Darapsky degradation,

:[[File:Degradación de Darapsky.png|800px|Darapsky degradation]]

Acyl azides react with amines to give aminimides (R3N+N−C(=O)R′).

Historical references

References

References

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3. Munch-Petersen, Jon. (1953). "''m''-Nitrobenzazide (Benzoyl azide, ''m''-nitro-)".
4. (1961). "Modified Curtius reaction". J. Org. Chem..
5. (2007). "Advanced Organic Chemistry: Part B: Reactions and Synthesis". Springer.
6. (1980). "Formation and Curtius rearrangement of acyl azides from unreactive acid chlorides". Synth. Commun..
7. (2008). "Direct Synthesis of Acyl Azides from Carboxylic Acids by the Combination of Trichloroacetonitrile, Triphenylphosphine and Sodium Azide". [[Synlett]].
8. (1987). "Azide synthesis with stable nitrosyl salts". Tetrahedron Lett..
9. (1972). "New convenient reagent for a modified Curtius reaction and for peptide synthesis". J. Am. Chem. Soc..
10. (2007). "Advanced Organic Chemistry: Part B: Reactions and Synthesis". Springer.
11. (2003). "Radical Azidonation of Aldehydes". [[J. Org. Chem.]].
12. Smith, Peter A. S.. (1946). "The Curtius reaction". [[Org. React.]].
13. (1988). "Azides: Their preparation and synthetic uses". [[Chem. Rev.]].
14. (1951). "Synthesis of Amino Acids from Substituted Cyanoacetic Esters". [[Can. J. Chem.]].
15. E. H. Rodd. (1965). "Chemistry of Carbon Compounds".
16. (1952). "Synthesis of α-Amino Acids from Ethyl Cyanoacetate". [[Can. J. Chem.]].
17. Wawzonek, Stanley. (1980). "Chemistry of Aminimides". Industrial & Engineering Chemistry Product Research and Development.