Asymmetric Hydrogenation of Unfunctionalized Enamines Catalyzed by Iridium Complexes of Chiral Spiro N,N-Diarylphosphoramidites
作者:Pucha Yan、Jianhua Xie、Qilin Zhou
DOI:10.1002/cjoc.201090293
日期:2010.9
Chiral spiro N,N‐diarylphosphoramidites were synthesized. These new chiral spiro monophosphoramidites were efficient ligands for iridium‐catalyzedasymmetrichydrogenation of unfunctionalized enamines derived from simple alkyl aryl ketones, providing chiral tertiary amines in good enantioselectivities (up to 90% ee).
Remarkable co-catalyst effects on the enantioselective hydrogenation of unfunctionalised enamines: both enantiomers of product from the same enantiomer of catalyst
作者:Sergey Tin、Tamara Fanjul、Matthew L. Clarke
DOI:10.1039/c5cy02051d
日期:——
During studies on the enantioselective hydrogenation of unfunctionalised enamines, a very surprising switch in enantiopreference was observed; [((R,R)-Et-DUPHOS)-Rh(COD)]BF4 hydrogenates an enamine to give (R)-amine with up to 73% ee, but when iodine is added as a co-catalyst, the (S)-amine is formed with up to 61% ee. Mechanistic studies implicate a protonation-iminium ion reduction pathway.
Rhodium catalysts derived from a fluorinated phanephos ligand are highly active catalysts for direct asymmetric reductive amination of secondary amines
作者:Sophie H. Gilbert、Sergey Tin、José A. Fuentes、Tamara Fanjul、Matthew L. Clarke
DOI:10.1016/j.tet.2020.131863
日期:2021.1
An asymmetric hydrogenation of enamines is efficiently catalysed by rhodium complexed with a fluorinated version of the planar chiral paracyclophane-diphosphine ligand, Phanephos. This catalyst was shown to be very active, with examples operating at just 0.1 mol% of catalyst. This catalyst was then successfully adapted to Direct AsymmetricReductive Amination, leading to the formation of several tertiary
Chiral Diselenides from Benzylamines: Catalysts in the Diethylzinc Addition to Aldehydes
作者:Thomas Wirth、Klaus J. Kulicke、Gianfranco Fragale
DOI:10.1002/hlca.19960790718
日期:1996.10.30
synthetic sequence (Scheme 1). Only 1 mol-% of these diselenides catalyzed very effectively the diethylzincaddition to various aromatic and α,β-unsaturated aldehydes yielding the secondary alcohols in up to 98% ee (Scheme 2 and Tables 1 and 2). An asymmetric amplification was observed with these catalysts. Detailed NMR studies were performed to characterize the catalytically active species.