Enantio‐ and Diastereoselective Desymmetrization of 1,1’‐Biaryl‐2,6‐dicarbaldehydes by Copper‐Catalyzed 1,2‐Addition of Silicon Nucleophiles

A desymmetrizing 1,2‐addition of silicon nucleophiles to biaryl derivatives containing an 2,6‐dicarbaldehyde‐1‐yl unit is reported. The reaction is catalyzed by copper with a triazolium‐derived N‐heterocyclic carbene as the chiral ligand and an Si–B reagent as the silicon pronucleophile. The practical methodology furnishes axially chiral aromatic carbaldehydes decorated with a centrally chiral α‐hydroxysilane moiety in moderate to high yields and with high enantio‐ as well as excellent diastereoselectivities. The silicon nucleophile always attacks at either carbonyl group away from the ortho substituent on the phenyl ring at C1 of the 2,6‐dicarbaldehyde‐1‐yl fragment. The resulting axially and centrally chiral products can be further converted into valuable biaryl compounds with hardly any erosion of the enantiomeric excess.