[Zurück]

F. Scharinger, Á. Pálvölgyi, V. Zeindlhofer, M. Schnürch, C. Schröder, K. Schröder:
"Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones";
ChemCatChem, 12 (2020), 14; S. 3776 - 3782.

We present a novel strategy for organocatalytic transfer hydro-
genations 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 combina-
tion of a chiral cation with a structurally flexible anion resulted
in a novel chiral framework for asymmetric transfer hydro-
genations with enhanced selectivity through synergistic effects.
The optimized catalytic system, in combination with a Hantzsch
ester as hydrogen source for biomimetic transfer hydrogena-
tion, enabled high enantioselectivity and excellent yields for a
series of ,-unsaturated cyclohexenones under mild condi-
tions. 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.

organocatalysis, asymmetric synthesis, transfer hydrogenation, ion aggregation, phosphoric acid, counterion catalysis

http://dx.doi.org/10.1002/cctc.202000414