Phenylsilane as been reassed as useful coupling reagent for amides synthesis. Peptides and Weinreb amides are easily obtained under mild conditions in absence of epimzerization even with challenging substrates such as phenylglycine. Further investigation regarding the reactivity of stable acetoxysilanes supported phenylpolyacyloxysilane as key intermediate.
Enantioselective Conjugate Addition of 2-Acylimidazoles with Nitroalkenes Promoted by Chiral-at-Metal Rhodium(III) Complexes
作者:Ganesh Kumar Thota、Gui-Jun Sun、Tao Deng、Yi Li、Qiang Kang
DOI:10.1002/adsc.201701377
日期:2018.3.20
An enantioselective conjugate addition of 2‐acylimidazoles with nitroalkenes catalyzed by chiral‐at‐metal rhodium(III) complex under mild reaction conditions was developed, affording versatile γ‐nitro ketone skeletons in good yields with excellent enantioselectivities (up to >99% ee).
functionalizations of more distal C-H bonds in hydrocinnamoyl ketones, Weinreb amides, and biphenyl Weinreb amides. Mechanistically, the coordination of these carbonyl groups and the bisdentate amino acid ligand with Pd(II) centers provides further evidence for our early hypothesis that the carbonyl groups of the potassium carboxylate are responsible for the directed C-H activation of carboxylicacids.
Rh/Lewis Acid Catalyzed Regio-, Diastereo- and Enantioselective Addition of 2-Acyl Imidazoles with Allenes
作者:Pranjal P. Bora、Gui-Jun Sun、Wei-Feng Zheng、Qiang Kang
DOI:10.1002/cjoc.201700596
日期:2018.1
A highly regio‐, diastereo‐ and enantioselective addition of 2‐acylimidazoles or 2‐acyl pyridines with allenes promoted by Rh/Lewis acid synergistically catalytic system is described. This atom economic approach leads to the formation of the branched allylic alkylated products including acyclic quaternary all‐carbon stereogenic centres in good yields with good to excellent diastereo‐ and enantioselectivities
A nickel(II)-catalyzed asymmetric direct vinylogous Michael addition of γ-alkyl monosubstituted α,β-unsaturated butyrolactams to α,β-unsaturated carbonyl compounds has been disclosed, affording γ,γ-dialkyl substituted butyrolactams in good yields and satisfactory enantioselectivities. A tandem catalyticasymmetric vinylogous Michael addition/intramolecular Michael addition has also been developed based
镍( II )催化的γ-烷基单取代的α,β-不饱和丁内酰胺与α,β-不饱和羰基化合物的不对称直接乙烯基Michael加成,以良好的收率和令人满意的对映选择性得到γ,γ-二烷基取代的丁内酰胺。基于该反应还开发了串联催化不对称插烯迈克尔加成/分子内迈克尔加成,这使得能够构建具有三个连续立体碳中心的对映体富集的八氢吲哚。