Asymmetric catalysis: preparation of chiral alcohols and their derivatives from highly functionalized organozinc reagents and application of new chiral ligands supported on magnetic nanoparticles

Abstract

The Asymmetric Catalysis plays a fundamental role in the construction of new chemical bonds in stereocontroled manner. There are several methodologies that allow the synthesis of enantiomerically pure compounds, among them we highlight the asymmetric metal catalyzed reactions. In this context the enantioselective addition of organozinc reagents to aldehydes and ketones in the presence of chiral ligands have received special attention, once since it is possible to obtain secondary or tertiary alcohols with high enantioselectivity, which are important precursors in the synthesis of pharmacologically and biologically active compounds. Recently, different approaches have been employed in the preparation of new poly-functionalized organozinc reagents. The low reactivity allows for the presence of many functional groups in these reagents. Many of these new reagents have been used successfully in several reactions, such as cross-coupling reactions catalyzed by palladium or nickel, acylation reactions, allylation among others. However there are few examples in the scientific literature regarding the use of these reagents in asymmetric reactions. Although the past decade has brought many advances in the preparation of new poly-functionalized organozinc reagents, it is evident that the application of these reagents in enantioselective transformations is still incipient, requiring the use of chiral ligands that can lead to formation of highly functionalized products in excellent enantiomeric excesses. In this sense, we aim to present in this project the use of these reagents in the presence of chiral ligand for the preparation of chiral functionalized alcohols and also some derivatives with biological activity. Epoxides and chiral azrididines will be also prepared by using poly-functionalized diorganozinc reagents. This project also will involve the preparation and application of new nanoparticle-supported and magnetically recoverable chiral catalyst in enantioselective addition reactions of organozinc reagents to carbonyl compounds. (AU)