One-Pot Reactions for Modular Synthesis of Polysubstituted and Fused Pyridines
作者:Zhidong Song、Xin Huang、Wenbin Yi、Wei Zhang
DOI:10.1021/acs.orglett.6b02883
日期:2016.11.4
3-dicarbonyl-initiated one-pot Michael addition/[5 + 1] annulation/dehydrofluorinative aromatization reaction sequence is introduced for regioselectivesynthesis of di-, tri-, tetra-, and pentasubstituted pyridines as well as fusedpyridines. This simple and modular synthesis is performed using readily available starting materials and under transition-metal catalyst-free conditions.
A one-pot fluorination and organocatalytic Robinson annulation sequence has been developed for asymmetric synthesis of 6-fluoroyclohex-2-en-1-ones and 4,6-difluorocyclohex-2-en-1-ones. The reactions promoted by cinchona alkaloid amine afforded products bearing two or three stereocenters in good to excellent yields with up to 99% ee and 20:1 dr.
A new sequential defluorination route to α-fluoro-α,β-unsaturated ketones from trifluoromethyl ketones
作者:Hiroshi Hata、Takeshi Kobayashi、Hideki Amii、Kenji Uneyama、John T. Welch
DOI:10.1016/s0040-4039(02)01343-6
日期:2002.8
double defluorination. Trifluoromethyl ketones were transformed to β,β-difluoroenol silylethers which were then coupled with aldehydes and ketones to β-hydroxy-α,α-difluoroketones. A second Mg-promoted defluorination of the hydroxyketones followed by acid-catalyzedhydrolysis of γ-hydroxy-β-fluoroenol silylethers provided α-fluoro-α,β-unsaturated ketones as a final product.
Achieving control over the diastereoselectivity of 1,3-dipolar cycloaddition reactions to obtain maximum number of diastereomers under simple operation is an enduring challenge. In this work, the diastereodivergent 1,3-dipolar cycloaddition of α-fluoro-α,β-unsaturated arylketones and azomethineylides was studied experimentally and theoretically. The reaction produced pyrrolidines (endo- and exo-adducts