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Combining Fluorous and Triazole Moieties for the Tagging of Chiral Azabis(oxazoline) Ligands
Author(s) -
Rasappan Ramesh,
Olbrich Tobias,
Reiser Oliver
Publication year - 2009
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.200900129
Subject(s) - chemistry , oxazoline , catalysis , combinatorial chemistry , triazole , selectivity , alkyne , alkyl , organic chemistry , cycloaddition , 1,2,3 triazole , polystyrene , click chemistry , nitroaldol reaction , polymer chemistry , enantioselective synthesis , polymer
New fluorous‐tagged azabis(oxazoline) ligands were prepared using the copper‐catalyzed azide‐alkyne cycloaddition as ligation method. The resulting ligands were tested in copper‐catalyzed asymmetric benzoylations (up to 99% ee ), nitroaldol (up to 90% ee ), and Michael reactions (up to 82% ee ). The combination of unpolar fluorinated alkyl chains and polar triazole moieties imposes properties that are beneficial for the catalysts with respect to recyclability and selectivity. The scope and limitation of this strategy in comparison to analogous catalysts immobilized on methoxypolyethylene glycol (MeOPEG) or polystyrene is discussed. Moreover, this study shows that the choice of solvent for a given reaction is crucial to arrive at highly recyclable bis(oxazoline) catalysts.