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New Axially Chiral Bis(dihydrooxazoles) as Ligands in Stereoselective Transition‐Metal Catalysis
Author(s) -
Rippert Andreas Johannes
Publication year - 1998
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19980810318
Subject(s) - chemistry , cyclopropanation , steric effects , ethyl diazoacetate , stereoselectivity , catalysis , asymmetric induction , adduct , styrene , transition metal , chirality (physics) , medicinal chemistry , stereochemistry , enantioselective synthesis , organic chemistry , chiral symmetry , copolymer , polymer , nambu–jona lasinio model , physics , quantum mechanics , quark
The new, axially chiral bis(4,5‐dihydrooxazoles) 4 have been synthesized in a straightforward manner, starting from the substituted, racemic 1,1′‐biphenyl‐2,2′‐dicarboxylic acids 1 and optically active amino alcohols 2 . The adducts were resolved by medium‐performance liquid chromatography (MPLC; see Scheme 1 ). Formation of Cu 1 complexes of 4 was followed by 1 H‐NMR spectroscopy. The catalytic behavior of these complexes has been investigated by asymmetric cyclopropanation of styrene with ethyl diazoacetate. Beside the influence of steric factors, a significant electronic effect on asymmetric induction could also be observed (see Scheme 2 and Table ).