Ketenimines

[Image:ketenimine.png|thumb|right|100px|General structure of a ketenimine]
Ketenimines are a group of organic compounds with the general structure. A ketenimine is a cumulated alkene and imine and is related to an allene and a ketene. When the substituents on the terminal carbon differ, the ketenimines are intrinsically chiral owing to the non-linearity of the C=N-R group.
Ketenimines can be prepared by reactions of isocyanates with Wittig reagents:
Similarly, aza-Wittig reagents react with ketenes to give ketenimines:
This method was employed in the preparation of the first example of a ketenimine.

Astronomical detection

The parent ketenimine has a distinctive rovibrational spectrum. The ν₈ and ν₁₂ bands in the high-resolution FTIR spectrum are pair of Coriolis-coupled bands. They provide a rare example where intensity sharing between bands yields sufficient intensity for an otherwise invisible band.