Compounds containing simple carbonyl and amine functionalities have been shown to act as both substrates and catalysts. A proline-catalyzed Mannich reaction utilizing acetaldehyde as substrate (Scheme 12a) may be compared with the hydrolysis of diamino maleonitrile, the HCNtetramer (Scheme 12b). This process starts with the same step as the Mannich reaction, but the roles of catalyst and substrate are reversed in the cycle that ensues. The hydrolysis of diamino maleonitrile is arguably an important step for a putative synthesis of RNA.