The synthesis of bis (oxazoline) ligand 1 bearing a spiro skeleton is achieved via double ring-closing metathesis (RCM) of tetraene 2 and subsequent oxazoline ring formation using N-bromosuccinimide (NBS). The Cu-spiro bis (oxazoline) complexes prepared from 1 and Cu (OTf) 2 or Cu (OAc) 2 act efficiently as chiral catalysts for promoting carbonyl-ene reactions or Henry reactions with good enantiocontrol.
