Calow, A. D. J., Carbó, J. J., Cid, J., Fernández, E., & Whiting, A. (2014). Understanding α,β-Unsaturated Imine Formation from Amine Additions to α,β-Unsaturated Aldehydes and Ketones: An Analytical and Theoretical Investigation. The Journal of Organic Chemistry, 79(11), 5163–5172.
In previous work, the researchers had reported a catalytic method to synthesize chiral γ-amino alcohols via in situ generation of α,β-unsaturated imines. They stated that there was a lack of kinetic or mechanistic studies regarding the relative 1,2- versus 1,4- addition of primary amines to α,β-unsaturated aldehydes and ketones. To further this understanding, the researchers used in situ ReactIR spectroscopy along with NMR studies and DFT calculations, to better characterize the addition of primary amines to α,β-unsaturated aldehydes and ketones (1,2- vs 1,4-addition) and examine the relative rates of these reactions.
ReactIR data showed that when benzylamine was added to crotonaldehyde, 1,2- addition resulted exclusively whereas when benzylamine was added to methyl vinyl ketone, 1,4- addition resulted exclusively.