Reduction of Nitroalkene Isomers by Base-Induced Equilibration

Significance

The authors report a highly practical and efficient reduction of isomeric mixtures of 1a and 1b to give the corresponding chiral nitro compound in high yield and enantiomeric excess. Prior to this work, the authors reported the asymmetric reduction of nitroalkene 1a (Angew. Chem. Int. Ed. 2003, 42, 4793). However, in the presence of adventitious base or after prolonged storage 1a isomerizes to give 1b. Addition of n-Bu₄OH to the reaction mixture converts 1b into 1a without any loss of catalytic activity.