臺灣博碩士論文加值系統

Asymmetric organocatalysis in particular plays the key role in the formation of assorted chiral molecules. Synthesis of organic compounds are usually achieved via the stepwise formation of the individual bond in the target molecule. Although this methodology has reached a considerable success, yet the formation of several bonds in single sequence without isolating the intermediates, changing the reaction conditions, or adding reagents thus makes the reaction an ecologically and economically favorable with respect to stepwise reactions. Additionally, the sequential organization of cascade double Michael reaction is required for an efficient reaction. The ever-expanding contributions of asymmetric organocatalytic 1,4-conjugate addition reactions confirm that this field of research continues to be very attractive for synthetic chemists and further exciting discoveries of novel chiral organocatalysts are to be expected in the near future.
This dissertation compiles our novel discovery in the area of asymmetric organocatalyzed cascade Michael reactions via iminium-enamine activation of carbonyl compounds and their application towards the synthesis of biologically active natural products and their intermediates.
The second chapter introduces the organocatalytic direct self-trimerization of acrolein afforded novel adduct dialdehyde 14 on preparative scale as a result of sequentially organized cascade double-Michael/Mannich reaction and equilibrium process. Furthermore, its application to the total synthesis of biologically active natural product montiporyne F (15) has been successfully proved.
Third chapter discusses the organocatalytic double Michael reactions of 7-oxohept-2-enoate to nitrostyrene. The first conjugate addition and subsequent intramolecular cyclization afforded the highly functionalized cyclohexane carboester with four stereogenic centers with high diastereoselectivity and high enantioselectivity (>99% ee). Some adducts were transformed into the intermediates for the synthesis of (–)-

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