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Iridium‐Catalyzed Enantioselective Hydrogenation of Terminal Alkenes
Author(s) -
McIntyre Steven,
Hörmann Esther,
Menges Frederik,
Smidt Sebastian P.,
Pfaltz Andreas
Publication year - 2005
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200404256
Subject(s) - iridium , chemistry , enantioselective synthesis , catalysis , aryl , asymmetric hydrogenation , oxazoline , ligand (biochemistry) , spin isomers of hydrogen , hydrogen , organic chemistry , medicinal chemistry , alkyl , biochemistry , receptor
Iridium complexes derived from chiral P,N ligands are efficient catalysts for the enantioselective hydrogenation of 2‐aryl‐substituted terminal alkenes. Using 0.1–1 mol % of catalyst at room temperature and ambient hydrogen pressure, high enantioselectivities (88–94% ee), full conversions after short reaction times and essentially quantitative yields were obtained for a range of differently substituted 2‐arylalkenes. Among six iridium complexes that were tested, the most selective catalyst was a complex with a phosphinite‐oxazoline ligand derived from threonine (Ir‐ThrePHOX). In contrast to the hydrogenation of trisubstituted alkenes, a strong pressure effect was observed for this class of substrates. Lowering the hydrogen pressure from 50 to 1 bar resulted in a strong increase of the ee values.