Direct Catalytic Asymmetric Addition Of Allylic Cyanides To Ketoimines

摘要

Catalytic enantioselective construction of a chiral tetrasub-stituted carbon center through an intermolecular C-C bond-forming reaction remains an intriguing challenge in modern organic synthesis. Catalytic asymmetric additions to ketoimines using active organosilicon or organometallic nu-cleophiles, e.g., TMSCN, allylboronates, enol silyl ethers, and dialkyllzinc, were recently developed as a new entry in this category. The formation of a C-C bond via proton transfer through catalytic generation of nucleophiles from otherwise inactive pronucleophiles, however, is an obviously more advantageous protocol that has been rarely explored in this class of reactions except for HCN or highly active α-alkoxycarbon-ylketoimines. Diastereoselective or racemic direct addition of nitroalkanes to ketoimines has been outlined via proton transfer conditions.