Biosynthesis of Terpenes. Preparation of (E)-1-Hydroxy-2-methyl-but-2-enyl 4-Diphosphate, an Intermediate of the Deoxyxylulose Phosphate Pathway

(E)-1-hydroxy-2-methyl-but-2-enyl 4-diphosphate (E-6) was synthesized in six reaction steps from hydroxyacetone (9) and (ethoxycarbonylmethenyl)-triphenylphosphorane (11) with an overall yield of 38%. The compound was shown to be identical with the product of IspG protein, which serves as an intermediate in the nonmevalonate terpene biosynthetic pathway.