Investigations On The Metal-catalyzed Diazo-carbene Involved Cascade Reactions

Metal carbene, which generated from diazo compounds, has receivedgreat attention due to its unique reactivity in organic synthesis. Meanwihle,transition metal-catalyzed decomposition of diazo compounds is one of themost important methods to give the formation of this type of complexes. Onthe other hand, the development of various organic transformation in one-pot,namely the cascade, tendem and domino reactions, which featured advantagesof atom economy and high synthetic efficiency, is always a hot research areafor the organic chemists. This dissertation is mainly focused on the study ofcascade reactions involving metal carbene which generates from thedecomposition of diazo compounds. There are four parts for this dissertation:1. We investigated a controllable CuI-catalyzed cross-coupling reactionbetween diazoacetamide and terminal alkynes, which allows chemoselectivesynthesis of diverse substituted dienamides and3-butynamides under differentreaction conditions. Further investigation disclosed that base can promote thetransformation from3-butynamides to dienamides.2. A palladium-catalyzed cascade reaction of N-H insertion andintramolecular Heck cyclization has been studied, which afforded a efficientapproach for the synthesis of indoles and quinolines. Additionally, thechemoselective synthesis of indoles or quinolines can be achieved just bychanging the subsitituents on the anilines as well as the diazo compounds.When alkylvinyldiazoacetates were employed in the reaction, migratoryinsertions occurred and delivered the corresponding cyclization product inmoderate to high yields.3. We have described a novel copper-catalyzed cascade process of N-Hinsertion and oxidative aromatization, which afforded a new protocol toprepare various2-arylamino-phenols. The N-H insertion intermediate hasbeen successfully isolated, which confirmed that the first transformation iscopper-catalyzed N-H insertion and the second is copper-catalyzedoxygenative aromatization. With the newly established methodology, anefficient way to access the natural1-oxygenated carbazole alkaloids has beenaccomplished. 4. A palladium-catalyzed cascade reaction of N-H insertion and oxidativedehydrogenative aromatization has been developed under relatively mildreaction conditions, which provided a alternative way to synthesize various2-amino-phenols. When aromatic amines were employed, PdCl2displayed thebest catalytic activity, while Pd(TFA)2worked better for the aliphatic amines.