New method for C–H arylation/alkylation at α-position of cyclic aliphatic ethers by iron-oxide mediated reaction
作者:Parvinder Pal Singh、Satish Gudup、Hariprasad Aruri、Umed Singh、Srinivas Ambala、Mahipal Yadav、Sanghapal D. Sawant、Ram A. Vishwakarma
DOI:10.1039/c1ob06660a
日期:——
We report a new and efficient iron oxide catalyzed cross-coupling reaction between organometallic species such as alkyl/arylmagnesium halides or organolithium species and α-hydrogen bearing cyclic unbranched and branched aliphatic ethers via activation of C(sp3)–H. In the presence of 1 mol% of iron oxide, five and six membered unbranched cyclic ethers such as tetrahydrofuran and tetrahydropyran gave
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
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