Investigation of the stereochemistry of the dehydration of the diketide, (3R)-3-hydroxybutyrate to crotonate, in the first chain extension cycle on the aspyrone polyketide synthase in intact cells of Aspergillus melleus

Abstract

When samples of the diketide, (3R)-3-hydroxybutyrate, labelled stereospecifically with deuterium at C-2 in the Re and Si positions, are administered to Aspergillus melleus, and the resulting aspyrone examined by ²H NMR, the (2R-)-[2-²H₁]-enantiomer gives a much higher level of incorporation at the expected position which is consistent with a syn elimination mechanism.