Lewis acid-catalyzed[4+2]cycloaddition of 3-alkyl-2-vinylindoles withβ,γ-unsaturatedα-ketoesters

A Lewis acid-catalyzed[4+2]cycloaddition of 3-alkyl-2-vinylindoles withβ,γ-unsaturatedα-ketoesters has been established in the presence of Sc(OTf)3,which afforded a series of indole-containing pyran derivatives in generally good yields(up to 90%yield)with excellent diastereoselectivities(up to >95:5 dr)under mild conditions.This approach not only enriches the chemistry of 3-alkyl-2-vinylindoles,but also has provided an atom-economic method for the synthesis of indole-containing pyran derivatives with potential bioactivity.

Selective Synthesis of 2,6-Dimethylnaphthalene by Transalkylation in the Presence of Acid Ionic Liquids [C_nmim]Cl-AlCl_3

A highly selective synthesis of 2,6-dimethylnaphthanlene（2,6-DMN） by transalkylation between 2-methylnaphthanlene（2-MN） and 1,2,4,5-tetramethylbenzene（TeMB） was performed with 1-alkyl-3-methylimidazo- lium aluminum chloride（[Cnmim]Cl-AlCl3） ionic liquids（ILs） as catalysts. The influences of the alkyl group as the organic cation, the acidic strength of [C4mim]Cl-AlCl3 ILs as well as the reaction conditions on the catalytic performance were investigated. [C4mim]Cl-AlCl3 ILs[x（AlCl3）=71%] exhibited high activity and selectivity toward 2,6-DMN. The selectivity to 2,6-DMN and the 2,6-DMN/2,7-DMN ratio reached up to 68.2% and 3.7：1, respectively. The UV-Vis spectrum of TeMB treated by different ILs shows that the protonated degree of TeMB dependeds on the acidity strength of ILs, which has a significant impact on the reaction results. The high protonated degree of TeMB is advantageous to enhancing the conversion of transalkylation and the large stereo-hindrance effect of TeMB is favorable to improving the selecivity to 2,6-DMN.

Asymmetric synthesis of pyrrolo[1,2-a]indoles via organocatalytic[3+2]annulation of substituted 2-vinylindoles with azlactones

The chiral phosphoric acid catalyzed asymmetric[3+2]annulation of substituted 2-vinylindoles with azlactones has been established.This reaction represented a practical approach for the synthesis of structurally diverse pyrrolo[1,2-a]indoles with two vicinal stereocenters including one tetrasubstituted stereocenter in good yields and good stereoselectivities under mild conditions.

Organocatalytic Stereoselective Synthesis of 3-Alkyl-3-hydroxy-2-oxindoles Catalyzed by Novel Water-compatible Axially Unfixed Biaryl-based Bifunctional Organocatalysts

In this work,six novel axially unfixed biaryl-based water-compatible bifunctional organocatalysts were de-signed and synthesized for the organocatalytic access to a variety of 3-alkyl-3-hydroxy-2-oxindole derivatives via aldol reactions in water.Organocatalyzed by 5a,the direct aldol reactions of isatins with enolisable ketones under-went readily in water,furnishing the structurally diverse 3-alkyl-3-hydroxy-2-oxindoles in various stereoselectivi-ties(up to>99%dr and>99%ee).Moreover,a plausible transition state of the conducted aldol reactions was hy-pothesized to shed light on the observed stereoselectivities of the obtained 3-alkyl-3-hydroxy-2-oxindoles.

Facile One-pot Synthesis of Ethyl 3-Alkyl-4-hydroxy-2-thioxothiazolidine-4-carboxylates

Ethyl 3-alkyl-4-hydroxy-2-thioxothiazolidine-4-carboxylates were prepared in excellent yields from the reaction of corresponding primary amines with carbon disulfide and ethyl 3-bromo-2-oxopropanoate in the presence of anhydrous potassium phosphate in DMF at room temperature within 1 h. The structures of the highly functionalized products were corroborated spectroscopically （IR, ^1H NMR, ^13C NMR, EI-MS） and by elemental analyses. A plausible mechanism for such type of cyclization was proposed.