Asymmetric Silaboration of Terminal Allenes

Significance

β-Borylallylsilanes are useful allylation reagents, allowing an easy preparation of functionalized chiral alkenylboron derivatives. Especially interesting are methods allowing the synthesis of chiral borylallylsilanes, which may serve, for example, as building blocks for the enantioselective synthesis of complex natural products. The combination of a chiral silylborane derivative and a chiral Pd-catalyst gives rise to a highly stereoselective reaction even in the case of mismatched combinations. Chiral α- and β-alkoxy- and -silyl­oxyallenes are suitable substrates for the reaction. Some interesting stereoselective transformations of the products are also described.