Recently, CuH-catalyzed reductive coupling processes involving carbonyl compounds and imines have become attractive alternatives to traditional methods for stereoselective addition to carbonyls due to their ability to use readily accessible and stable olefin as surrogates for organometallic nucleophiles. However, the inability to use aldehydes, which usually reduce too rapidly in the presence of copper hydride complexes to be viable substrates, has been a major limitation. We show that by exploiting relative concentration effects through kinetic control, we can invert this intrinsic reactivity and achieve the reductive coupling of 1,3-dienes with aldehydes. Using this method, both aromatic and aliphatic aldehydes can be transformed to synthetically valuable homoallylic alcohols with high levels of diastereo- and enantioselectivity and in the presence of many useful functional groups. Furthermore, using a combination of theoretical (DFT) and experimental methods, important mechanistic features of this reaction related to stereo- and chemoselectivity were uncovered.
“Engaging Aldehydes in CuH-Catalyzed Reductive Coupling Reactions: Stereoselective Allylation with Unactivated 1,3-Diene Pronucleophiles”, Angew. Chem. Int. Ed., 2019, 58, 17074-17080.