Phosgene is a very useful molecule, but it's often not the best for the situation, and it has the unfortunate side effect of being a gas. A war gas.

Carbonyl diimidazole isn't exactly a pussycat; by nature, it has to be very reactive. At least it's not a gas. It's a useful phosgene alternative that acts very much like an acyl chloride. It finds some use in peptide synthesis, along with various other spheres of organic chemistry.

Molecules: You'd better learn to live with them.


Comments
Is this structure correct? It's difficult to generate imidazole C-anion...
Posted by: AS | April 20, 2007 11:56 PM
Fixed, thanks.
Posted by: Molecule of the Day | April 21, 2007 2:10 AM
Its always worth trying this reagent if you have a difficult amide coupling; I know of two projects that were saved by CDI.
Posted by: Handles | April 22, 2007 6:51 PM