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 B₂hex₂ to afford 2,4-dien-1-ols as the product in the presence of Cs₂CO₃ as the base, ⁱPrOH as the additive, and 1,4-dioxane as the solvent. And they react with B₂pin₂ to form boronic half acids in the presence of NaO^tBu 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.