Enantioselective Henry reaction catalysed by Chiral-copper(II) Complexes: Chirality effect derived from ligand backbone and Side-chain

Abstract

• Two diastereopure camphor-derived iminomethylpyridine ligands were resolved. • Distorted square planar geometry has been featured around the Cu(II) complexes. • Phenyl propionaldehyde and CH 3 NO 2 reaction yields > 99 % 1-nitro-4-phenylbutan-2-ol. • ee > 99 % resulted in opposite configurations with R , R , S and R , R , R -Cu(II) complexes. • The combined backbone and side-chain chirality of the ligand governed the activity. Copper(II) complexes based on two diastereopure camphor-derived iminomethylpyridine ligands were resolved and structurally characterised by single-crystal X-ray diffraction. Each chiral Cu(II) complex was an efficient catalyst for theenantioselective Henry reaction of phenyl propionaldehyde and nitromethane, affording 1-nitro-4-phenylbutan-2-ol in high yields (up to 99%) and excellent enantioselectivities (up to 99%) that were governed by the combined chirality effect of the ligand backbone and side-chain.