Nitroalkenes in the Ni(II) Catalyzed Asymmetric<i>Michael</i>Addition. Convenient Route to the Key Intermediate of Brivaracetam

Abstract

Abstract A series of Ni(II) complexes with novel chiral ligands derived from (1 R ,2 R )‐1,2‐diphenylethane‐1,2‐diamine was synthesized. The catalytic activity of these complexes in the asymmetric Michael reaction is demonstrated. Asymmetric addition of diethyl malonate to ω ‐nitrostyrene and 1‐nitropent‐1‐ene in the presence of these complexes leads to the enantiomerically enriched diethyl ( S )‐2‐(2‐nitro‐1‐phenylethyl)malonate (up to 96 % ee ) and ( R )‐diethyl 2‐(1‐nitropenthan‐2‐yl)malonate (up to 91 % ee ). (4 R )‐4‐Propylpyrrolidin‐2‐one, the key intermediate of antiepileptic drug brivaracetam, was obtained from the corresponding nitroester.