Strong Base-Promoted Pd-Catalyzed Asymmetric Hydroalkoxylation of Alkoxyallene

A new protocol for the Pd-catalyzed hydroalkoxylation of alkoxyallene is presented that proceeds under strongly basic conditions. Notably, this method accommodates sterically hindered tertiary alcohols and carbohydrate-derived alcohols, which proved unreactive under the previous base-free conditions. This result was rationalized by the outer-sphere addition of alkoxide nucleophile to the <i>syn</i> π-allyl complex. Synthetic utility of the reaction was demonstrated by convergent synthesis of [1,4]-linked pentasaccharide.