Cobalt-catalyzed oxidative cyclization of gem -disubstituted conjugated alkenols
作者:Tânia M.F. Alves、Mateus O. Costa、Beatriz A.D. Bispo、Fabiana L. Pedrosa、Marco A.B. Ferreira
DOI:10.1016/j.tetlet.2016.06.064
日期:2016.7
Aryl gem-disubstituted conjugated alkenols underwent oxidativecyclization affording 2,5,5-trisubstituted tetrahydrofurans in reasonable yields and good diastereoselectivities using the reductive termination variation of the Mukaiyama aerobic oxidative reaction. Under oxidative termination, the same alkenols produced diols and ketonic by-products via the double hydration and beta-scission competing
Numerous electrophilic thiocyano oxyfunctionalization reactions of alkenes have been achieved using N-thiocyano-dibenzenesulfonimide, which is a newelectrophilic thiocyanation reagent and could be easily prepared in two steps from dibenzenesulfonimide. This approach provides efficient, simple, and modular methods for the formation of SCN-containing heterocycles such as lactones, tetrahydrofurans,
triiodide was the most effective catalyst, whereas typical Lewis acids such as TiCl4, AlCl3, and BF3·OEt2 were ineffective. Many functional groups were successfully introduced, and these resulted in yields of 31–86%. Various styrene derivatives were also applicable to this reaction. Mechanistic investigation revealed that the present hydrofunctionalization proceeded through Brønsted acid-catalyzed intramolecular
Reported here is a copper‐catalyzed 1,2‐methoxy methoxycarbonylation of alkenes by an unprecedented use of methyl formate as a source of both the methoxy and the methoxycarbonyl groups. This reaction transforms styrene and its derivatives into value‐added β‐methoxy alkanoates and cinnamates, as well as medicinally important five‐membered heterocycles, such as functionalized tetrahydrofurans, γ‐lactones
A facile and efficient enantioselectivebromoaminocyclization of unsaturated sulfonamides has been developed using an amino-thiocarbamate catalyst. A range of enantioenriched pyrrolidines were prepared with up to 99% yield and 99% ee. The corresponding lactams could be obtained through oxidation of the pyrrolidines.