Indium-Mediated Preparation of Bis(α-hydroxyallenes) or α,α'-Dihydroxyallenynes and Further Gold-Catalyzed Cyclizations.

We present the regio- and diastereoselective Barbier-type allenylation reaction of glyoxals mediated by indium to furnish highly valuable syn -bis(α-hydroxyallenes) and syn -α,α'-dihydroxyallenynes. The gold-catalyzed controlled cyclization of these unsaturated diols enables the divergent preparation of three types of oxacycles.