Studies On Biomimetic Synthesis Of Hyperolactones And Biyouyanagin B

The thesis aims at the studies on synthesis of natural products spirolactones Hperolatone B-D, 4-epi-Hyperolactone C,4-hydroxyHyperolactone D through a common biomimetic way. The synthesis of Hyperolactone C and its isomers provide a foundation for studies on total synthesis of anti-HIV natural product Biyouyanagin B. The dissertation consisted of mainly two parts as follows:Chapter 1:Studies on the Biosynthesis of Hyperolactones and Biyouyanagin BSpirolactone copound Hyperolactones and anti-HIV natural product were isolated from Hypericum plant and there were many work about their syntheis. What our group wanted to do is to find a common biomimetic way to finish their synthesis. Through a biomimetic way from methyl acetoacetate via Weiler's dianion method, asymmetric allylic alkylation, biomimetic lactonization, oxidation and cyclization, we synthesized concisly Hyperolactone D 4-hydroxyHyperolactone D, Hyperolactone C and its isomers, and also determined it's absolute configuration. With isobutyraldehyde and methyl acetoacetate as starting materials, the synthesis of Hyperolactone B was fininshed though the same procedure.The synthesis of compound Hyperolactones provided a good opportunity for study on synthesis of Biyouyanagin B. According to K.C.Nicolaou and our's synthetic experience, we synthesized the reported Biyouyanagin B with its two precusors 4-epi-Hyperolactone and natural Zingiberene and found its wrong structure. For synthesizing Biyouyanagin B and determining its structure, we synthesized a series of biyouyanagins compound and analyzed the structure of the natural Biyouyanagin B.Chapter 2:Studies on the methods of synthesizing a-hydroxy-β-dicarbonyl compounds (review)The substructure unit a-hydroxy-β-dicarbonyl can be found in biologically important compounds such as vindorosine and vindoline. For its importance as key intermediates in the synthesis of natural products, there were many efforts toward the construction of the motif in the development of organic history. One impotant way was the a-hydoxylation of 1.3-dicarbonyl compounds. This thesis summarized 68 references about sythsizing the substructure and it was especially a review for the construction of tert-hydroxy.There were mainly two parts consisted in this section:studies on the methods with oxygen involved and methods without oxygen involved. In addition to the above, the other methods including enantioselectivity were summarized briefly.