The Studies Of Asymmetric Organocatalytic Novel Michael Addition And Caseade Reaction

In this article, we have developed some novel asymmetric Michael additions and cascade reactions with Jorgensen-Hayashi catalyst. Besides, we designed and synthesized a new type of tertiary amine-thiourea bifunctional catalyst and realized the synthesis of chiral curcumin derivatives.The first enantioselective direct Michael reaction ofα,β-unsaturated aldehyde with acetophenone was developed under base-base bifunctional catalysis. This approach posseses the advantages of easily available starting materials, the atoms economy and the simple manipulation. Futhermore, it is also a powerful tool for the access to synthetically importantδ-keto aldehyde, which has an good potential application. The Michael addition products could be obtained in up to 82% yield and 91:9 of regioselectivity. Besides, all of the ee values were higher than 94%(up to 98%).We have developed an environmentally friendly method to realized the asymmetric cyclopropanation reactions between chloroacetophenones andα,β-unsaturated aldehydes with Jφrgensen-Hayashi catalyst, which provided the cyclopropane motifs in high diastereo- and enantioselectivities. The cyclopropanation products could be obtained in high yields (up to 85%) and excellent diastereo-(8:1->30:1) and enantioselectivities (90%->99%). It should be noted that this approach posseses the mild experimental conditions, low cost of the experiment and the excellent stereoselectivities.We have developed a novel and simple organocatalytic domino Michael-Aldol reaction betweenα,β-unsaturated aldehyde and bifunctional nucleophile of imidazole derivative under iminium-enamine mechanism. Catalyzed by Jφrgensen-Hayashi catalyst and 2-nitrobenzoic acid, the cascade reactions could proceed in high yields and excellent diastereo- and enantioselectivities. This process could provide the products in one pot in high yields (up to 95%) with 6:1->30:1 dr and 87%->99% ee. A broad substrate scope has been successfully employed in this process, including aromatic and alkyl a. (3-unsaturated aldehydes.Catalytic asymmetric Michael additions between nitroolefins and curcumin derivatives were developed for the synthesis of the chiral curcumin derivatives by a new type of tertiary amine-thiourea catalyst. The Michael products could be afforded in up to 96% yield and excellent ee values (84-97%). This methodology is not only an important development of the asymmetric Michael addition of nitroolefin, but also provides a method for synthesis of chiral curcumin derivatives, which provide the possibility of further drug bioactivity tests.