STEREOCHEMISTRY OF ALDOL REACTIONS WITH 3-HEXULOSE PHOSPHATE SYNTHASE

The enzymic reaction between ribulose-5-phosphate (1) and formaldehyde or acetaldehyde catalyzed by hexulose phosphate synthase (HPS) from M ethylomonas M 15 DSM 580 yielded D-arabino-3-hexulose-6-phosphate (2) and two new 7-deoxy-4-heptulose-1-phosphates (4, 6). By various NMR-sp ectroscopic methods, especially NOED, the configuration of the dephosp horylated products was established as (5R,6S) and (5R,6R). The configu ration of two earlier described 7,8-oxy-4-octulose-1-phosphates (8, 10 ) synthesized likewise by HPS catalysis must be corrected.