(formula presented) A chiral bis(isoxazoline) ligand (SPRIX) containing a rigid spiro skeleton was designed and synthesized via a double intramolecular nitrile oxide cycloaddition. The optically pure SPRIX greatly accelerated the Cu(acac)2-catalyzed asymmetric reaction of diisopropylzinc with cyclohexenone to give the Michael adduct with 49% ee. This is the first example of the use of an isoxazoline ligand for a transition metal-catalyzed reaction. The X-ray crystallographic analysis of the hexacoordinated copper complex of SPRIX confirmed the ligand character.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry