Studies On Asymmetric Organocatalyzed Reactions

Based on the new concepts and new methodologies in the field of current asymmetric catalysis, this thesis mainly focused on the design, synthesis and application of chiral amine organocatalysts in asymmetric transformations. The details are summarized below:In Chapter 1, the significant progress of asymmetric aminocatalysis in the past ten years has been briefly reviewed. Representative activation modes, catalysts and types of reactions were listed. New directions and challenges in this field were also proposed.In Chapter 2, the background knowledge of polymer-supported catalysts was introduced. Two novel polystyrene-supported chiral amino alcohols were synthesized and applied as catalysts to promote enantioselective addition of diethylzinc to aldehydes. Good to excellent yields and moderate ees were accomplished in the ethylation of most aromatic aldehydes. The polymer-supported catalysts were easily separated and fully recycled without diminishing the catalytic effectiveness in five successive cycles.In Chapter 3, the development of thiourea bifunctional organocatalysts as well as the progress of asymmetric alcoholysis of meso-cyclic anhydrides were briefly reviewed. A novel inexpensive tertiary amine-thiourea bifunctional organocatalysts were developed from a by-product in the industrial production of chloramphenicol for the highly efficient asymmetric alcoholysis of a series of bi-and tricyclic succinic anhydrides and monocyclic glutaric anhydrides. The catalyst showed great activity and stereoselectivity in the preparation of (3aS,6aR)-lactone, a key chiral building block of d-biotin, which provided an effective strategy for the asymmetric total synthesis of d-biotin. Moreover, quantum chemical calculations were carried out to provide theoretical explanation for the predominant configuration of the product as well as the observed stereoinduction ability of the catalysts.In Chapter 4, the progress of secondary amine-catalyzed asymmetric domino reactions was briefly reviewed, and an unprecedentedly efficient pyrroridine-catalyzed cascade oxa-Michael—Mannich—1,3-rearrangement reaction between salicyl N-tosylimine derivatives andα,β-unsaturated aldehydes was developed, which enables the rapid access to highly optically pure benzopyran derivatives at room temperature in quantitive yields with a broad substrate tolerance. Moreover, the a plausible mechanism of the unexpected 1,3-nucleophilic rearrangement was proposed.