Studies On Total Synthesis Of Natural Product Conidiogenone

This thesis consists of two parts:partⅠis mainly about the studies on the total synthesis of natural product Conidiogenone.Conidiogenone is a novel natural product isolated from fermentation broth ofpenicillium cyclopium,and its new carbon skeleton was first reported.There are seven chiral centres,but only two functional groups on the molecule. It shows strong conidiation inducing activity,and it can completely induce conidiation of penicillium cyclopium at extremely low concentration(from 10^-7 to 10^-8 M). Moreover,the discovery of this natural product can well explain the elusive triggering system of conidiogenesis in fungi.Therefore,it is significant to synthesize this novel and important compound from the view of academe as well as application.In this thesis we have finished the synthesis of compound 8 starting from the cheap and easily available material such as acetoacetic acid ethylester.We have also investigated the synthesis of compound 23 from compound 8,which is an important intermediate for Conidiogenone.Intramolecular cyclization of 2,5-diketone,Michael addition, bromization,andα-oxidation of ketone were included in the synthesis.Moreover,we have optimized reaction conditions to seek applicable,high-yielding and economical methods for the synthesis of compound 8.In addition,we explored many methods of the synthesis of compound 23,which laid a solid foundation for the synthesis of the key intermediate 23.PartⅡmainly studies the synthesis of penta-heterocyclic compounds,which frequently occur in natural products and pharmaceutical compounds.Especially many polysubstituted penta-heterocyclic compounds present different bioactivities such as antibacterial,antiviral,anti-inflammatory,antioxidant.Therefore,studies on the synthesis of penta-heterocyclic compounds are very significant.In this thesis,we have synthesized wide variety of highly substituted furans and pyrroles by Paal-Knorr reaction.Besides,we have developed several efficient environmentally-friendly methods for Paal-Knorr reaction by using some green catalysts and reaction medium.In addition,we have proposed plausible mechanism for Paal-Knorr reaction.