Synthetic Studies Of Rubrolone Aglycon And Silver(â… )-Catalyzed Ring-Contractive Rearrangement Of5-Substituted6-Diazo-2-cyclohexenones

This dissertation is mainly concentrated on the synthetic study towards the skeleton constructions of Rubrolone aglycon and the methodology study towards silver(â… )-catalyzed ring contraction rearrangement of5-substituted6-diazo-2-cyclohexenones.Part â… :Synthetic study of Rubrolone aglyconThe first generation strategy began with the Suzuki coupling between3,5-dimethoxyphenylboronic acid and polysubstituted pyridine, synthesized the diazoketone via Danheiser diazo transfer reaction, the skeleton of Rubrolone aglycon was constructed by the Buchner reaction. The oxidation of cycloheptatriene to tropone was easily achieved when we used SiO2/O2as oxidant, unfortunately, the two C=O bonds were in syn plane.The second generation strategy initiated with the Suzuki coupling between2,3,5-trimethoxyphenylboronic acid and polysubstituted pyridine. The trimethoxyl-substituted cycloheptatriene was formed via Rhodium(â…¡) catalyzed Buchner reaction as a key step. Rubrolone aglycon could be synthetized via deprotection/oxidation from trimethoxyl-substituted cycloheptatriene compound. However, we have not obtained the target molecular so far.Part â…¡:Ag(â… )-catalyzed ring-contraction rearrangement of5-substituted6-diazo-2-cyclohexenonesA novel silver(â… )-catalyzed ring-contractive rearrangement has been developed to synthesize5-alkylidene-2-cyclopentenones. This reaction is conducted in the presence of AgOTf forming silver-carbenoid, followed by the endocyclic allyl [1,2] migration to afford the desired products. In this method various6-diazo-2-cyclohexenones bearing5-substituted group could be engaged with good yields and excellent stereoselectivity. Further applications in total synthesis of natural products are in progress.