P-Tether-Mediated, Iterative SN2'-Cuprate Alkylation Strategy to Skipped Polyol Stereotetrads: Utility of an Oxidative "Function Switch" with Phosphite-Borane Tethers.

The development of a P-tether-mediated, iterative SN2'-cuprate alkylation protocol for the formation of 1,3-skipped polyol stereotetrads is reported. This two-directional synthetic strategy builds molecular complexity from simple, readily prepared C2-symmetric dienediols and unites the chemistry of both temporary phosphite-borane tethers and temporary phosphate tethers-through an oxidative "function switch" of the P-tether itself-to generate intermediates that were previously inaccessible via either method alone.