A General, Asymmetric, and Noniterative Synthesis of Trideoxypropionates. Straightforward Syntheses of the Pheromones (+)-Vittatalactone and (+)-Norvittatalactone

A novel, highly stereocontrolled, and very flexible synthetic
access
to biologically relevant trideoxypropionate building blocks in optically
pure form has been developed. On the basis of a three-step sequence
comprising a thermal oxy-Cope rearrangement, an iridium-catalyzed
hydrogenation, and an auxiliary-controlled enolate methylation, trideoxypropionates
with easily adjustable relative configuration were synthesized in
excellent yields. In addition, the functionalized end groups allow
for chemoselective manipulations and further elongation of the chain.
The underlying strategy constitutes the first noniterative process
for the assembly of polydeoxypropionates and has further been applied
in total syntheses of the pheromones (+)-vittatalactone and (+)-norvittatalactone, which had been isolated from the striped cucumber beetle Acalymma
vittatum.