Curtius Rearrangement · Acyl Azide → Isocyanate
unseel.com · RCON₃ → R-N=C=O + N₂ · retention of config
Stage acyl azide
N₂ lost 0
Step acyl azide assembled
R group (migrates)
Carbonyl carbon
Oxygen
Nitrogen
N₂ leaving / trap
Unseel.com · Curtius Rearrangement