Synthesis of chiral homogeneous and heterogeneous Betti bases andinvestigation of their catalytic activity in the Kharasch-Sosnosky reaction

The enantioselective formation of C-H, C-C, C-O, and C-N bonds is an attractive methodfor producing single enantiomers, and chiral catalysts are the most effective means ofachieving this goal[۱].Chiral Betti bases are one of the important classes of compounds thatpossess beneficial biological properties and have been extensively studied for their catalyticapplications in asymmetric organic reactions. These compounds can be used as chiral ligandsin asymmetric allylic C-H bond oxidation, also known as enantioselective Kharasch-Sosnovsky reaction to prepare functional alkenes such as chiral allylic esters[۲, ۳].In thisstudy, nanoporous silica SBA-۱۵ was prepared using a hydrothermal method andfunctionalized with ۳-chloropropyltrimethoxysilane.Chiral Betti base ligands were thensynthesized via a multicomponent reaction of ۲-naphthol, benzaldehyde, and ammoniumacetate, and the resulting enantiomers were separated by diastereomeric crystallization [۳].The obtained chiral Betti bases were immobilized on functionalized SBA-۱۵. The preparedchiral homogeneous and heterogeneous ligands were investigated in the Kharasch-Sosnovskyreaction by varying parameters such as temperature, solvent, and the amount of homogeneousand heterogeneous chiral ligands and copper salts (Scheme ۱). The resulting chiral allylicesters were obtained in high yields and moderate enantioselectivities. These findings suggestthat the mentioned ligands have promising applications as catalysts in the enantioselectiveKharasch-Sosnovsky reaction.

کلیدواژه ها:

Betti base ، Chiral homogeneous and heterogeneous catalyst ، Chiral allylic esters ، Kharasch-Sosnovsky reaction