Cu-Catalyzed Catalytic Diboration of Aldehydes

Significance

Methods of formation of a new carbon-heteroatom σ-bond are highly desirable for synthetic organic chemistry. The authors developed the first practical method for the direct addition of boranes to the C=O bond, leading to α-hydroxyboranes, potentially useful equivalents of α-oxycarbanions. The reaction proceeds smoothly with a variety of aryl-, hetaryl-, and alkylcarbaldehydes, affording uniformly high yields of products. The resulting boronic esters are sufficiently stable for isolation and storage and open an interesting perspective for use in synthesis.