To understand the catalytic power of enzymes and to account quantitatively for the large rate accelerations they bring about is a challenging task. Model systems have given insight into how enzymes achieve their high efficiency and it is now possible to explain part of enzymic catalysis with 'ordinary' chemical reasoning. For the most common class of biological reactions, proton transfer, few models exhibiting high efficiency are available. Recent work in Cambridge has shown that highly efficient proton transfer in enol ether and acetal hydrolysis is possible, when strong intramolecular hydrogen bonds are present. Workers in the U.S. (in particular Gerlt and Gassmann) have independently come to a similar conclusion. We want to follow this lead and propose to synthesize and test several models for enolases and racemases. They are designed to shown high efficiency for the reverse reaction, i.e. abstraction of protons in Alpha-position to carbonyl groups.