Synthesis of chiral oxazoline based ligands with aliphatic substituents and their application in Kharasch-Sosnovsky reaction

Allylic oxidation of alkenes is one of the most important reactions in organic chemistry, in this reaction double bond is remained unchanged while the second functional group is formed. The stereochemistry of this reaction can be controlled by the use of asymmetric methods.1 Using chiral catalysts, especially heterogeneous chiral catalysts have drawn a lot of attention among all other methods because they can be separated easily and reused for the production of enantiorich compounds. One way to produce these catalysts is to immobilize chiral ligands onto mesoporous substrates.2 For this purpose, chiral amino oxazoline ligands such (S)-4- isobutyl-4,5-dihydroxazole-2-amine and (S)-4-isopropyl-4,5-dihydroxazole-2-amine were synthesized from inexpensive and available amino acids and then immobilized onto Cl- MCM-41. The copper (I) complexes of the obtained chiral heterogeneous ligands were used in asymmetric allylic oxidation of alkenes with perseter as oxidant under different conditions. The chiral allylic esters were obtained in good yields and enantioselectivities.3

Keywords:

Chiral oxazoline based ligands , Heterogeneous catalysts , Chiral allylic ester , Kharasch-Sosnovsky reaction