Studies On Asymmetric Decarboxylative Protonation Of Carbazolones

In recent years,because of innovative research of Stoltz and Trost, etc.the application of transitional metal palladium catalytic reaction of asymmetric decarboxylative protonation is more and more in the total synthesis of organic chemistry, Obviously, the asymmetric decarboxylation protonation reaction has become a kind of transformation method,which is very powerful building C3chiral center in organic synthesis. Although in the cyclic ketones, enol esters and a series of compounds as substrates have been successfully transformed, there is no report on the reaction for Pd-Catalyzed asymmetric enantioselective decarboxylative protonation of Four hydrogen carbazole ketone and other similar compounds. This paper mainly research is based on four hydrogen carbazole ketone and other similar compounds as substrate,though the reaction of the palladium catalyzed enantioselective decarboxylation protonation,we has gained an important chiral tertiary carbon chiral centers protonation four hydrogen carbazole ketone products, the structure of this product in many natural products are found. Asymmetric structure of active drug molecules in medicinal chemistry and biology in the chiral C3chiral centers, in organic synthesis in the modern is very difficult and has got a lot of chemists’ favor, So based on the above facts, our research group reports the reaction of asymmetric decarboxylation protonation in the natural product of synthesis of (-)-Aspidofractinine.In this paper, the content about the reaction of the asymmetric decarboxylation protonation is mainly divided into three parts:The first part is the study progress about the reaction of decarboxylation protonation.The second part is mainly eqperiment, the reaction conditions,which are the disire ligands for palladium catalyst asymmetric decarboxylation protonation reaction, the catalyst, the reaction temperature, the proton dpnors for providing protonation, the reaction solvent and the amount for solvent are screened through model reaction for by Four hydrogen carbazole and its derivative as Substrate, finally we get the optimal reaction conditions for the reaction get, with palladium acetate as the catalyst,(s)-tBu-PHOX as the ligand, toluene as the solvent,80℃as the reaction’s temperature, methyl2-oxocyclopentanecarboxylate as the proton donor,which are as the reaction conditions, with92%of the chemical yield and92%of Stereoselectivity. But also the reaction substrates of the reaction are expanded, so that the reaction conditions can adapt to the substrates,which have a substituent on the phenyl ring, different protective group on the nitrogen atom, different substituents in a position of ketone carbonyl group, we can achieve better results. The reaction to the synthesis of (-)-Aspidofractinine provides a new method.The third part has carried on the summary to this topic.