Ketenimines are a group oforganic compounds with the general structureR2C=C=NR'. A ketenimine is a cumulatedalkene andimine and is related to anallene and aketene.[1] 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 ofisocyanates 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.[2]
The parent ketenimine (CH2CNH) has a distinctiverovibrational 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 (ν12).[3][4]
