Studies On The Asymmetric Total Synthesis Of Hydramicromelin B And Methylcleomiscosin D

The dissertation aims at the studies on the asymmetric total synthssis of a few naturally occurring coumarinolignoids and cembrane diterpene, sarcophytonolide E. It consists of the following four parts:Chapter 1. Organocatalytic Enantioselective Michanel and hetero-Michael (Review)The enantioselective methods reported to date for carrying out conjugate additions of carbon- and heteroatom-centered nucleophiles to electron-deficient olefins, using small chiral organic molecules as catalysts, are reviewed.Chapter 2. Enantioselective Total Synthesis of Hydramicromelin B.The definition, classification of coumarins were introduced briefly. The approach of enantioselective total synthesis of Hydramicromelin B was studied starting from 2,4-dimethoxybenzaldehyde using Sharpless AD reaction, Wittig reaction and an AuCl₃/AgOTf catalyzed intramolecular reaction as key steps, meanwhile the absolutely configuration was established.Chapter 3. The first asymmetric total synthesis of coumarinolignoids enantiomer of Methylcleomiscosin D.The definition, classification of lignans and previous synthetic reports of coumarinolignoids were introduced briefly. The first asymmetric total synthesis of coumarinolignoids enantiomer of Methylcleomiscosin D was accomplished starting from 7-hydroxycoumarin and 3,4,5-trimethoxybenzaldehyde, in which Sharpless asymmetric dihydroxy reaction was used to construct chiral center, and Mitsunobu reaction was used to obtain product.. Chapter 4. Study on the enantioselective total synthesis of cembrane diterpene Sarcophytonolide EThe syntheses of cembrane diterpene lactone compounds was introduced briefly. Starting from the natural commercially L - glutamic acid as chiral materials, Using Sharpless asymmetric epoxidation reaction and intramolecular HWE reaction to form the five-membered ring lactone and completed the precursor of key fragments of Sarcophytonolide E.