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Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones
Author(s) -
Scharinger Fabian,
Márk Pálvölgyi Ádám,
Zeindlhofer Veronika,
Schnürch Michael,
Schröder Christian,
BicaSchröder Katharina
Publication year - 2020
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.202000414
Subject(s) - counterion , organocatalysis , chemistry , catalysis , transfer hydrogenation , chirality (physics) , selectivity , phosphoric acid , combinatorial chemistry , organic chemistry , enantioselective synthesis , ion , chiral symmetry breaking , ruthenium , physics , quantum mechanics , quark , nambu–jona lasinio model
We present a novel strategy for organocatalytic transfer hydrogenations relying on an ion‐paired catalyst of natural l ‐amino acids as main source of chirality in combination with racemic, atropisomeric phosphoric acids as counteranion. The combination of a chiral cation with a structurally flexible anion resulted in a novel chiral framework for asymmetric transfer hydrogenations with enhanced selectivity through synergistic effects. The optimized catalytic system, in combination with a Hantzsch ester as hydrogen source for biomimetic transfer hydrogenation, enabled high enantioselectivity and excellent yields for a series of α,β‐unsaturated cyclohexenones under mild conditions. Moreover, owing to the use of readily available and chiral pool‐derived building blocks, it could be prepared in a straightforward and significantly cheaper way compared to the current state of the art.