Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: enhancement of the reaction rate and selectivity by a base
Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: enhancement of the reaction rate and selectivity by a base
作者:Lin Wang、Zhi-Gang Ma、Xiao-Jing Wei、Qing-Yuan Meng、Deng-Tao Yang、Shao-Fu Du、Zi-Fei Chen、Li-Zhu Wu、Qiang Liu
DOI:10.1039/c4gc00337c
日期:——
An efficient visible-light-driven photocatalytic oxidation of various 2-substituted dihydropyrimidines and phenolic imines has been achieved using an organic photocatalyst eosin Y bis(tetrabutyl ammonium salt) (TBA-eosin Y) and inexpensive oxidant molecular oxygen. With the aid of a base, significantly enhanced photoinduced electron transfer from substrates dihydropyrimidines or phenolic imines to the excited state of TBA-eosin Y has enabled the aerobic oxidation to yield 2-(methylthio)pyrimidines or 2-arylbenzoxazoles selectively.
Enantioselective Aza-Diels−Alder Reaction of Aldimines with “Danishefsky-Type Diene” Catalyzed by Chiral Scandium(III)-<i>N</i>,<i>N</i><i>‘</i>-Dioxide Complexes
A new kind of complex prepared from scandium(III) triflate and l-proline-derived N,N‘-dioxides has been developed to catalyze the enantioselective aza-Diels−Alder reaction between 1,3-butadiene (diene 1) and aldimines 2, affording the corresponding 2,5-disubstituted dihydropyridinones in moderate to high yields (up to 92%) with good enantioselectivities (up to 90% ee) at room temperature. A variety
First enantioselective organocatalytic allylation of simple aldimines with allyltrichlorosilane
作者:Sunil B. Jagtap、Svetlana B. Tsogoeva
DOI:10.1039/b611823b
日期:——
A new organocatalytic system, novel chiral bisformamide 3 and in situ generated L-proline-derived allylsilane reagent 14′, which converts different aldimines to homoallylic amines in good to high yields (up to 95%) and good enantioselectivities (up to 85% ee) has been described.
A new cobalt-based heterogeneous catalyst was prepared by adsorbing in situ produced nitrogen-ligated cobalt(II) acetate complexes on commercially available SiO2 and subsequent pyrolysis at 800 degrees C for 2 h under N-2 atmosphere. By applying this catalyst under the O-2 balloon, the aerobic oxidation of phenolic imines proceeded smoothly and gave various 2-arylbenzoxazoles in good yields. Meanwhile, on the basis of the experimental results, a plausible reaction pathway was described to elucidate the reaction mechanism.
Allylsilane–Vinylarene Cross-Metathesis Enables a Powerful Approach to Enantioselective Imine Allylation
作者:John D. Huber、Nicholas R. Perl、James L. Leighton