The Curtius rearrangement (or Curtius reaction or Curtius degradation), as first defined by Theodor Curtius, is a chemical reaction that involves the rearrangement of an acyl azide to an isocyanate. Several reviews have been published.
The isocyanate can be trapped by a variety of nucleophiles. Water is often added in order to hydrolyze the isocyanate to an amine. When done in the presence of tert-butanol, the reaction generates Boc-protected amines, useful intermediates in organic synthesis.
Carboxylic acids 1 can be easily converted to acyl azides 3 using diphenylphosphoryl azide 2.
Likewise, when the Curtius reaction is performed in the presence of benzyl alcohol, Cbz-protected amines are formed.
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