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Cation‐Triggered Switchable Asymmetric Catalysis with Chiral Aza‐CrownPhos
Author(s) -
Ouyang GuangHui,
He YanMei,
Li Yong,
Xiang JunFeng,
Fan QingHua
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201411593
Subject(s) - rhodium , catalysis , cationic polymerization , chemistry , crown ether , intermolecular force , ligand (biochemistry) , phosphoramidite , asymmetric hydrogenation , ether , alkali metal , metal , polymer chemistry , enantioselective synthesis , combinatorial chemistry , organic chemistry , molecule , receptor , ion , dna , biochemistry , oligonucleotide
An aza‐crown ether, modified phosphoramidite ligand, has been designed and synthesized. The ON/OFF reversible switch of catalytic activity for its rhodium catalyst was thoroughly investigated in the asymmetric hydrogenation of dehydroamino acid esters modulated by host–guest interactions. In the OFF state, the catalyst is almost inactive (less than 1 % conversion) because of the formation of an intermolecular sandwich complex by two aza‐crown ether moities and the cationic rhodium metal center. In using alkali‐metal‐cations as the trigger, the catalytic activity was turned ON and consequently resulted in full conversions and excellent enantioselectivities (up to 98 % ee ).