Premium
Enantioselective hydrogenation of olefins with phosphinooxazoline‐iridium catalysts
Author(s) -
Blackmond Donna G.,
Lightfoot Andrew,
Pfaltz Andreas,
Rosner Thorsten,
Schnider Patrick,
Zimmermann Nicole
Publication year - 2000
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/(sici)1520-636x(2000)12:5/6<442::aid-chir25>3.0.co;2-f
Subject(s) - chemistry , hexafluorophosphate , iridium , enantioselective synthesis , catalysis , rhodium , phosphine , allylic rearrangement , asymmetric hydrogenation , ruthenium , tetrafluoroborate , trifluoromethyl , cationic polymerization , organic chemistry , noyori asymmetric hydrogenation , medicinal chemistry , ionic liquid , alkyl
Abstract Cationic iridium complexes with chiral phosphinooxazoline ligands are efficient catalysts for the enantioselective hydrogenation of olefins. The complexes are readily prepared, air‐stable, and easy to handle. In contrast to chiral rhodium‐ and ruthenium‐phosphine catalysts, they do not require the presence of a polar coordinating group near the C=C bond. In the hydrogenation of unfunctionalized trisubstituted 1,2‐diaryl‐olefins, high enantioselectivities of >95% ee with full conversion and turnover frequencies of >7,000 h −1 can be achieved, using 0.1 mol% of catalyst with tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate (TFPB or BARF) as the counterion. The corresponding hexafluorophosphate or tetrafluoroborate salts give low conversion due to deactivation of the catalyst during the reaction. Substrates with polar substituents such as allylic alcohols, on the other hand, afford better results with the hexafluorophosphate salts. Chirality 12:442–449, 2000. © 2000 Wiley‐Liss, Inc.