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A Selenourea-Thiourea Brønsted Acid Catalyst Facilitates Asymmetric Conjugate Additions of Amines to α,β-Unsaturated Esters
journal contribution
posted on 2020-03-10, 20:48 authored by Yingfu Lin, William J. Hirschi, Anuj Kunadia, Anirudra Paul, Ion Ghiviriga, Khalil A. Abboud, Rachael W. Karugu, Mathew J. Vetticatt, Jennifer S. Hirschi, Daniel Seidelβ-Amino
esters are obtained with high levels of enantioselectivity
via the conjugate addition of cyclic amines to unactivated α,β-unsaturated
esters. A related strategy enables the kinetic resolution of racemic
cyclic 2-arylamines, using benzyl acrylate as the resolving agent.
Reactions are facilitated by an unprecedented selenourea-thiourea
organocatalyst. As elucidated by DFT calculations and 13C kinetic isotope effect studies, the rate-limiting and enantiodetermining
step of the reaction is the protonation of a zwitterionic intermediate
by the catalyst. This represents a rare case in which a thiourea compound
functions as an asymmetric Brønsted acid catalyst.
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enantioselectivityestersracemic cyclic 2- arylaminesagentselenourea-thiourea organocatalystSelenourea-Thiourea Br ønstedEsterDFT calculationszwitterionicrate-limitingBr ønsted acid catalystbenzyl acrylatestrategyCatalyst Facilitates Asymmetric Conjugate Additionsβ-thiourea compound functions13 Cconjugate additionenantiodetermining stepcyclic aminesunactivatedisotope effect studiesprotonationAmineUnsaturatedAmino
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