[4+3] Cycloaddition To Construct Benzofunan Seven-membered Ring Skeleton And Total Synthesis Of Tardioxopiperazine B

This thesis aimed at the studies on the development of a [4 + 3] cycloaddition reaction to construct benzofunan seven-membered ring skeleton and studies on the total synthesis of Tardioxopiperazine B.Accordingly,the content could be divided into the following two parts: Charpter 1.Studies on the [4 + 3] Cycloaddition to Construct Benzofunan Seven-Membered Ring SkeletonThis chapter introduced the recent progress of the [4 + 3] cycloaddition,including Lewis acid-induced,transition-metal-catalyzed,and the asymmetric organocatalyzed [4 + 3] cycloaddition.As an efficient and brief method,[4 + 3] cycloaddition plays an important role in the total synthesis of complex natural products.In order to construct benzofunan seven-membered ring skeleton by employing [4 + 3] cycloaddition,we firstly synthesized benzofunan alcohols over two steps using salicylaldehyde as starting material.We then studied the Zn Cl2·Et2O induced-[4 + 3] cycloaddition of benzofunan alcohols with conjugated dienes,and 13 target molecules are obtained with yield up to 62%.This research provides a useful protocol to synthesize benzofunan seven-membered ring skeleton.Charpter 2.Studies on the Total Synthesis of Tardioxopiperazine BThis chapter firstly presented the isolation,identification,and research progress on the total synthesis of Tardioxopiperazine B and its derivatives.Due to their excellent bioactivity in low concentration(such as antibiosis,anti-radical oxidation,immunosuppression and antiultraviolet).Tardioxopiperazine B and its derivatives attracted great attention from biochemists.Based on the interests in activities and structures of these natural products,we chose Tardioxopiperazine B as the research target,and designed a new synthetic route for it.Key reactions included a Mannich reaction and a coupling reaction.By now,we have successfully synthesized the cyclization precursor 2-52 of the target molecule.The overall yield is 32% except the step of installation of prenyl.The successful preparation of the cyclization precursor 2-52 has laid a solid foundation for the total synthesis of Tardioxopiperazine B.Related work is still going on in our lab.In this thesis,49 compounds have been synthesized,among which 39 compounds are synthesized for the first time.These new compounds are identified by 1H,13 C NMR and mass spectrum.