A Mild and General <i>trans</i>-Diboration of Both Terminal and Internal Propargyl Alcohols

A practical and efficient <i>trans</i>-diboration of propargyl alcohols was accomplished using sodium hydride (NaH) as a base in <i>N</i>,<i>N</i>-dimethylformamide at room temperature. The mild reaction conditions demonstrate general applicability, facilitating the successful conversion of both terminal and internal propargyl alcohols with diverse structures and functional groups into highly functionalized alkenediboronates [4-borylated 1,2-oxaborol-2(5<i>H</i>)-oles]. The resulting products, which incorporate two boron groups, can be selectively activated and subjected to stepwise transformations, thereby providing an effective platform for synthesizing a wide range of structurally diverse trisubstituted alkenes.