Enzymatic Aldol Condensation/Isomerization as a Route to Unusual Sugar Derivatives

Preparative enzymatic synthesis of several unusual hexoketose and hexoaldose derivatives using fructose bisphosphate aldolase and glucose isomerase as catalysts has been developed. Fructose bisphosphate aldolase catalyzes a stereospecific aldol condensation between dihydroxyacetone phosphate and a number of aldehydes to form ketose 1-phosphates which upon removal of the phosphate groups by hydrolysis are converted stereospecifically to aldose derivatives catalyzed by glucose isomerase. These combined enzymatic processes allow preparation of 5-deoxy, 6-deoxy, 6-deoxy~6-fluoro-, and 6-O-methylhexoketoses and -hexoaldoses on 4-20-mmol scales. Dihydroxyacetone in the presence of inorganic arsenate has been found to be an effective substrate for fructose bisphosphate aldolase.