[2, 3]-Sigmatropic Rearrangement Of Sulfur Ylide Derived From Metal Carbene

The reaction of sulfide and metal carbene, in situ generated by transition metal-catalyzed decomposition of diazo compounds, is an efficient way to obtain the sulfur ylide. With this method, the preparation of the corresponding salts and the use of stoichiometric amount of base could be avoided. And this process has been widely applied in various organic reaction, especially in the [2,3]-sigmatropic rearrangement. Our research has focused on the application and metal-carbene precursors of [2,3]-sigmatropic rearrangement, and the competition of shift group in [2,3]-sigmatropic rearrangement.Firstly, we have developed an new synthetic method for 3-arylthio-1,3-disubstituted oxindoles via a cascade of Rh(II)-catalytic thia-Sommelet-Hauser rearrangement/intramolecular cyclization reaction, in which easily prepared sulfenamides and diazoacetates were employed as the starting materials. The key step of this method is the thia-Sommelet-Hauser rearrangement, which is a unique process involving [2,3]-sigmatropic dearomatization and subsequent 1,3-shift rearomatization. This catalytic reaction could be carried out under neutral conditions and low temperature. So, it has shown excellent functional group tolerance. With this approach, we have achieved a catalytic version of Gassman's oxindole synthesis.In order to expand the scope of metal-carbene precursors for catalyst [2,3]-sigmatropic rearrangement of sulfur ylide, we have investigated the reaction of N-tosylhydrazones with allyl or propargyl sulfides, and we have descovered that [2,3]-sigmatropic rearrangement of N-tosylhydrazones could be occured smoonthly in the presence of base. Considering the fact that unstable diazo compounds can be generated in-situ from N-tosylhydrazones, the [2,3]-sigmatropic rearrangement of unstable diazo compounds could be carried out by this way. Our study has been the first example [2,3]-sigmatropic rearrangement of sulfur ylide generated from N-tosylhydrazones. Moreover, we have demonstrated the efficacy of this methodology in organic synthesis.As we know, allyl, propargyl and allenic sulfides could be employed as the substrates for [2,3]-sigmatropic rearrangement. However, the competition of these groups and key influencing factors remain unclear when at least two type of shift groups existed in a reaction system. Thus, we have designed a series of intramolecular and intermolecular competition reactions of methyl-2-diazo-2-phenylacetate with allyl, propargyl and allenic sulfides. By measuring the ratio of the two products, we could compare the reactivity of the sulfides in [2,3]-sigmatropic rearrangement.