Immobilization of L-proline on functionalized MCM-۴۱ and its applicationin the synthesis of chiral allylic esters

Recently, metal-catalyzed organic reactions through C-H bond activation have attracted alot of attention from the point of view of atom economy, and also various types of catalyticprocesses have been developed using different modes to activate the existing bond [۱]. Allylicesters which can be prepared through allylic oxidation, play an important role as effectiveintermediates in the preparation of organic and pharmaceutical compounds[۲]. Using chiralcatalysts is an available, low-cost and effective method for the preparation of chiral products.Most of organic catalysts are homogeneous and require high molar concentrations; As a result,they increase the cost of separation. One of the ways to recover homogeneous catalysts is theimmobilization of them on different substrates, including inorganic substrates [۳]. In themeantime, mesoporous MCM-۴۱ has attracted countless attention due to its different advantagessuch as higher and better efficiency compared to other similar compounds [۴].For this purpose,MCM-۴۱ was prepared and functionalized by ۳-chloropropyl trimethoxy silane. Afterwards, thechiral L- proline ((۲S)-pyrrolidine-۲-carboxylic acid), was immobilized on it. Finally, the coppercomplex of synthesized chiral heterogeneous ligandwas used for the preparation of chiral allylicesters and the resulting chiral products were obtained in relatively good yields andenantioselectivities (Scheme ۱).