Nickel(II)-catalyzed asymmetric propargyl and allyl Claisen rearrangements to allenyl- and allyl-substituted β-ketoesters

Abstract

Highly efficient catalytic asymmetric Claisen rearrangements of O-propargyl β-ketoesters and O-allyl β-ketoesters have been accomplished under mild reaction conditions. In the presence of the chiral N,N'-dioxide/Ni(II) complex, a wide range of allenyl/allyl-substituted all-carbon quaternary β-ketoesters was obtained in generally good yield (up to 99%) and high diastereoselectivity (up to 99:1 d.r.) with excellent enantioselectivity (up to 99% ee).

Keywords: allenic compounds; asymmetric catalysis; heterocycles; nickel; rearrangement.