Curtius rearrangement

Also known as: Curtius degradation

Schematic of the Curtius rearrangement. Reagents: acyl azide, heat. Product: isocyanate.

The Curtius rearrangement is an organic reaction used to convert an acyl azide to an isocyanate under thermal conditions. The mechanism consists of an alkyl shift of the R group from the carbonyl carbon to the closest nitrogen with the release of nitrogen gas. The release of gas drives the reaction forward and results in the formation of the isocyanate product which can potentially react further in the presence of nucleophiles in solution.[1][2][3]

Mechanism

Mechanism of the Curtius rearrangement.

References:

1.
Curtius, T. Ber. Dtsch. Chem. Ges. 1890, 23, 3023–3033.
3.
Curtius, T. J. Prakt. Chem. 1894, 50, 275–294.