Cobalt‐Catalyzed Transfer Hydrogenation of α‐Ketoesters and
<i>N</i>
‐Cyclicsulfonylimides Using H
<sub>2</sub>
O as Hydrogen Source
作者:Yang Gao、Xuexin Zhang、Ronibala Devi Laishram、Jingchao Chen、Kangkui Li、Keyang Zhang、Guangzhi Zeng、Baomin Fan
DOI:10.1002/adsc.201900636
日期:2019.9.3
A Co‐catalyzed effective transferhydrogenation of various α‐ketoesters and N‐cyclicsulfonylimides by safe and environmentally benign H2O as hydrogensource is described. The reaction used easily available and easy to handle zinc metal as a reductant. Interestingly, the catalytic system does not require ligand for reduction of N‐cyclicsulfonylimides.
Reversal of reactivity: A chemoselective direct asymmetricMichaeladdition of cyclic N‐sulfonylimines to α,β‐unsaturated aldehydes has been developed by employing chiral iminium catalysis. A tandem base‐catalyzed tautomerization of the imine group/hemiaminal formation/dehydroxylation process of the Michael adducts efficiently affords valuable tricyclic piperidine derivatives in moderate to excellent
enantioselective Pd-catalyzed asymmetricallylic substitution cascade of cyclic N-sulfonylimines with an accompanying asymmetric desymmetrization has been developed for the construction of fused tetrahydroindole derivatives bearing two chiral centers. Mechanistic studies confirmed that the cascade reaction proceeds by initial allylicalkylation and subsequent allylic amination. The first alkylation is a chirality-control
Chiral sulfonylamines can be efficiently synthesized in good yields by asymmetric hydrogenation of cyclic and acyclic N‐sulfonylimines co‐catalyzed by Pd/Zn(OTf)2 using hydrogen gas under ambient pressure.
An N-heterocyclic carbene iridium catalyst with metal-centered chirality for enantioselective transfer hydrogenation of imines
作者:Yanjun Li、Meng Lei、Wei Yuan、Eric Meggers、Lei Gong
DOI:10.1039/c7cc04691j
日期:——
carbene iridium complex featuring metal-centered chirality was designed and applied to the asymmetric transfer hydrogenation (ATH) of imines. Four strongly σ-donating carbon-based substituents (2 carbenes and 2 phenyl moieties), a chirality transfer directly from the stereogenic metal center to the C=N bond of substrates, as well as a restriction of catalyst deactivation by steric demanding substituents