Activation of Chiral (Salen)TiCl2 Complex by Phosphorane for the Highly Enantioselective Cyanation of Nitroolefins

Org Lett. 2020 Mar 6;22(5):2099-2104. doi: 10.1021/acs.orglett.0c00612. Epub 2020 Feb 27.

Abstract

We report that phosphorane can activate (salen)TiCl2 complex to achieve unprecedented excellent enantioselectivity and a broad substrate scope in the cyanation of nitroolefins. Our cyanating reagent Me2(CH2Cl)SiCN proves to be more active than TMSCN in this reaction, allowing 11 β-aliphatic nitrolefins and 12 β-CF3 nitroolefins (either β-aryl or aliphatic) to work well to give the corresponding tertiary or quaternary β-nitronitriles with high to excellent enantioselectivity.