TY - JOUR
T1 - Copper(ii) complexes incorporating poly/perfluorinated alkoxyaluminate-type weakly coordinating anions
T2 - Syntheses, characterization and catalytic application in stereoselective olefin aziridination
AU - Li, Yang
AU - He, Jiayue
AU - Khankhoje, Vineeta
AU - Herdtweck, Eberhardt
AU - Köhler, Klaus
AU - Storcheva, Oksana
AU - Cokoja, Mirza
AU - Kühn, Fritz E.
PY - 2011/6/7
Y1 - 2011/6/7
N2 - The synthesis and characterization of a series of cationic copper(ii) complexes of the type [Cu(NCR)6][Al(OC(CF3) 2R′)4]2 (R = CH3, Ph; R′ = CF3, Ph, PhCH3), incorporating poly/perfluoronated alkoxyaluminates as weakly coordinating anions (WCAs) is presented. Aziridination of various olefins, such as the unreactive olefins e.g. ethylhex-2-enoate and 1-decene, with N-tosyliminophenyliodinane catalyzed by [Cu(NCR)6][Al(OC(CF3)2R′) 4]2 affords very good yields (up to 96%) and high TOFs (up to 5000 h-1) under mild conditions. Using disubstituted olefins as substrates, high stereoselectivities are obtained at room temperature. The to date highest cis:trans ratio (98:2) of the obtained aziridines is achieved for cis-stilbene in good yield (85%) as well as promising TOF (> 2000 h -1). The investigation of the solvent effect on yield and selectivity reveals that for certain oleophilic substrates (1-decene), less polar solvents, such as dichloromethane are a better choice than acetonitrile, which is commonly considered as the best solvent for olefin aziridination. Accordingly, a mechanism involving a paramagnetic copper nitrene intermediate with both concerted and stepwise pathways is proposed.
AB - The synthesis and characterization of a series of cationic copper(ii) complexes of the type [Cu(NCR)6][Al(OC(CF3) 2R′)4]2 (R = CH3, Ph; R′ = CF3, Ph, PhCH3), incorporating poly/perfluoronated alkoxyaluminates as weakly coordinating anions (WCAs) is presented. Aziridination of various olefins, such as the unreactive olefins e.g. ethylhex-2-enoate and 1-decene, with N-tosyliminophenyliodinane catalyzed by [Cu(NCR)6][Al(OC(CF3)2R′) 4]2 affords very good yields (up to 96%) and high TOFs (up to 5000 h-1) under mild conditions. Using disubstituted olefins as substrates, high stereoselectivities are obtained at room temperature. The to date highest cis:trans ratio (98:2) of the obtained aziridines is achieved for cis-stilbene in good yield (85%) as well as promising TOF (> 2000 h -1). The investigation of the solvent effect on yield and selectivity reveals that for certain oleophilic substrates (1-decene), less polar solvents, such as dichloromethane are a better choice than acetonitrile, which is commonly considered as the best solvent for olefin aziridination. Accordingly, a mechanism involving a paramagnetic copper nitrene intermediate with both concerted and stepwise pathways is proposed.
UR - http://www.scopus.com/inward/record.url?scp=79957454806&partnerID=8YFLogxK
U2 - 10.1039/c1dt10280j
DO - 10.1039/c1dt10280j
M3 - Article
C2 - 21523276
AN - SCOPUS:79957454806
SN - 1477-9226
VL - 40
SP - 5746
EP - 5754
JO - Dalton Transactions
JF - Dalton Transactions
IS - 21
ER -