Amino acid-catalysed retroaldol condensation: the production of natural benzaldehyde and other flavour compounds

The amino acid-catalysed retroaldol condensation previously described for citral has been extended to other α,β-unsaturated aldehydes. In the presence of glycine and an elevated pH, six other α,β-unsaturated aldehydes also underwent retroaldol condensation. Crotonaldehyde, as well as its proposed intermediate, aldol, were converted into acetaldehyde. Hexenal, decenal, methyl crotonaldehyde, farnesal and cinnamaldehyde were also converted into acetaldehyde plus butanal, octanal, acetone, geranyl acetone and benzaldehyde, respectively. Subsequently, the effects of temperature, pH, the buffer and substrate concentration on the conversion rate were studied, using the conversion of cinnamaldehyde into the important flavour compound benzaldehyde as a model. Copyright © 2004 John