Chiral Molecular Tweezers: Synthesis and Reactivity in Asymmetric Hydrogenation
摘要:
We report the synthesis and reactivity of a chiral aminoborane displaying both rapid and reversible H-2 activation. The catalyst shows exceptional reactivity in asymmetric hydrogenation of enamines and unhindered imines with stereoselectivities of up to 99% ee. DFT analysis of the reaction mechanism pointed to the importance of both repulsive steric and stabilizing intermolecular non-covalent forces in the stereodetermining hydride transfer step of the catalytic cycle.
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
First Detection of a Selenenyl Fluoride ArSe?F by NMR Spectroscopy: The Nature of Ar2Se2/XeF2 and ArSe?SiMe3/XeF2 Reagents
作者:Helmut Poleschner、Konrad Seppelt
DOI:10.1002/chem.200400596
日期:2004.12.17
Arylselenenyl fluorides ArSeF are obtained from diselenides Ar2Se2 or arylselenotrimethylsilanes ArSe-SiMe3, and XeF2. They are detected by low-temperature 19F and 77Se NMRspectroscopy. Substitution in the ortho position of the aromatic ring to provide electronic or steric protection is a requirement for their formation. ArSe--F compounds decompose according to 3 ArSe-F-->[ArSe-SeF2Ar]+ArSe-F-->ArSeF3+Ar2Se2
Enantioselective addition of diethylzinc to aldehydes catalyzed by (R)-1-phenylethylamine-derived 1,4-amino alcohols
作者:Masatoshi Asami、Naomichi Miyairi、Yukihiro Sasahara、Ken-ichi Ichikawa、Naoya Hosoda、Suguru Ito
DOI:10.1016/j.tet.2015.07.031
日期:2015.9
alcohols, synthesized from (R)-1-phenylethylamine, were used as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde. (S)-1-Phenyl-1-propanol was obtained with high enantioselectivity in all cases since the stereochemical outcome of the reaction was controlled by the chiral benzylic carbon bearing amino group. Highest catalytic activity was obtained by using (R)-1-2-[1-(pyrroli
The secondary amine participating asymmetricreductiveamination remains an unsolved problem in organic synthesis. Here we show for the first time that secondary amines are capable of effectively serving as N-sources in direct asymmetricreductiveamination to afford corresponding tertiary chiral amines with the help of a selected additive set under mild conditions (0–25 °C). The applied chiral phosphoramidite
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).