Synthesis of New Chiral Heterogeneous Catalysts by Immobilization of Aromatic Substituted Chiral Amino Oxazoline Ligands on Nonoporous SBA-15 and Their Applications in Asymmetric Allylic C-H Bond Oxidation of Cycloalkenes

Compounds containing a chiral oxazoline ring are one of the accessible and useful classes of ligands for asymmetric catalysis[1,2]. In the recent decade, using chiral heterogeneous catalysts for the synthesis of asymmetric allylic esters by oxidation of allylic C-H bond has attracted much attention in organic chemistry [3-5]. Herein chiral amino oxazoline ligands with aromatic substituent groups such as (S)-4-benzyl-4, 5 -dihydrooxazol-2-amine and (S)-4-phenyl-4, 5-dihydrooxazol-2-amine were synthesized from inexpensive and available amino acids. The obtained chiral ligands were grafted on ordered mesoporous silica SBA-15 and Characterized by TGA, DTA, BET, TEM, EDX, SEM and FT-IR. The catalytic and induced asymmetric effects of the copper (I) complexes of these new chiral heterogeneous ligands on the asymmetric allylic oxidation of cycloolefins with tert-butyl p-nitroperbenzoate as oxidant were investigated under different conditions.