Facile Enzymatic Aldol Reactions with Dihydroxyacetone in the Presence of Arsenate

Aldol reactions of in situ formed dihydroxyacetone arsenate with different aldehydes were catalyzed by bacterial D-fructose-1,6-bisphosphate aldolase (FruA). Aldolases from bacteria were found to be much more stable and active than FruA from rabbit muscle. Arsenate acts as a phosphate mimic and can, in principle, be used in catalytic amounts. The use of inorganic arsenate and dihydroxyacetone afforded high yields with hydrophobic aldehydes. Cosolvents increased the solubility of hydrophobic aldehydes and afforded higher reaction rates and enzyme stability. Insight is given, for the first time, in the influence of arsenate on the stereoselectivity of the aldol reaction.