Cu-Catalyzed Divergent Transformations of Allenylethylene Carbonates with Diboron Reagents.

Divergent transformations of allenylethylene carbonates with diboron reagents catalyzed by copper are disclosed. By using CuCl/IPr·HCl as the catalyst, the allenylethylene carbonates react with B 2 hex 2 to afford 2,4-dien-1-ols as the product in the presence of Cs 2 CO 3 as the base, i PrOH as the additive, and 1,4-dioxane as the solvent. And they react with B 2 pin 2 to form boronic half acids in the presence of NaO t Bu as the base, water as the additive, and THF as the solvent. The reactions afford corresponding products in good stereoselectivities and yields, and further derivatizations of boronic half acids and study of the mechanism are also demonstrated.