Zn-Catalyzed Enantio- and Diastereoselective Formal [4 + 2] Cycloaddition Involving Two Electron-Deficient Partners: Asymmetric Synthesis of Piperidines from 1-Azadienes and Nitro-Alkenes
作者:John C. K. Chu、Derek M. Dalton、Tomislav Rovis
DOI:10.1021/jacs.5b00033
日期:2015.4.8
We report a catalytic asymmetricsynthesis of piperidines through [4 + 2] cycloaddition of 1-azadienes and nitro-alkenes. The reaction uses earth abundant Zn as catalyst and is highly diastereo- and regioselective. A novel BOPA ligand (F-BOPA) confers high reactivity and enantioselectivity in the process. The presence of ortho substitution on the arenes adjacent to the bis(oxazolines) was found to
A highly efficient access to enantiopure tetrahydropyridines: dual-organocatalyst-promoted asymmetric cascade reaction
作者:Hua Lin、Yu Tan、Wen-Jie Liu、Zhi-Cheng Zhang、Xing-Wen Sun、Guo-Qiang Lin
DOI:10.1039/c3cc40690c
日期:——
A highly efficient cascade process of Michael–aza-Henry–hemiaminalization–dehydration was established for the construction of enantiopure tetrahydropyridines using the combination of prolinol trimethylsilyl ether and cinchona alkaloid catalysts. This new approach allowed for the application of aliphatic imines, generated in situ from aldehydes and amines. Good yields (up to 90%), high enantio- (up to >99% ee) and diastereoselectivities (>99 : 1 d.r. in all cases) were achieved for a broad spectrum of substrates under mild conditions.