Commeyras reported sigmoidal kinetic behavior in the synthesis of amino acids via hydration of aminonitriles. Kinetic studies revealed that carbonyl compounds (acetaldehyde or acetone) formed from partial decomposition of the aminonitrile can act to catalyze the hydration of the remaining aminonitrile (Scheme 5). This reaction presents a product-induced mechanism but does not correspond to a self-replicative autocatalytic model and does not directly offer a mechanism for enantioenrichment.