Asymmetric organocatalytic anthrone additions to activated alkenes
作者:Alex Zea、Andrea-Nekane R. Alba、Natalia Bravo、Albert Moyano、Ramon Rios
DOI:10.1016/j.tet.2011.02.032
日期:2011.4
Asymmetric organocatalyticadditions of anthrones to activated alkenes are discussed. The reaction between anthrone or dithranol and α,β-unsaturated aldehydes is catalyzed by diphenylprolinol trimethylsilyl ether in toluene at −40 °C, giving the Michael adducts with good yields and enantioselectivities. Bifunctional amino-thioureas efficiently catalyze the additions of anthrones to both nitroalkenes and maleimides
A chiral analog of the bicyclic guanidine TBD: synthesis, structure and Brønsted base catalysis
作者:Mariano Goldberg、Denis Sartakov、Jan W Bats、Michael Bolte、Michael W Göbel
DOI:10.3762/bjoc.12.176
日期:——
catalyzes Diels-Alderreactions of anthrones and maleimides (25-30% ee). It also promotes as a strong Bronsted base the retro-aldol reaction of some cycloadducts with kinetic resolution of the enantiomers. In three cases, the retro-aldol products (48-83% ee) could be recrystallized to high enantiopurity (>/=95% ee). The absolute configuration of several compounds is supported by anomalous X-ray diffraction
Simple chiral triethylsilyl-amino alcohol organocatalysts containing a bulky triethylsilyl group on the oxygen atom at the gamma-position were designed and synthesized as new organocatalysts for enantioselective Diels-Alder reactions of anthrones with maleimides to produce chiral hydroanthracene Diels-Alder adducts in up to 99% yield and with up to 94% ee. (c) 2015 Elsevier Ltd. All rights reserved.
Reversal of enantioselectivity induced by the achiral part of an organocatalyst in a Diels–Alder reaction
作者:Trupti S. Tawde、Swapnil J. Wagh、Jai V. Sapre、Vaibhav N. Khose、Purav M. Badani、Anil V. Karnik