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Tautomerism in Bis(oxazoline)s
Author(s) -
Walli Adam,
Dechert Sebastian,
Meyer Franc
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201301282
Subject(s) - tautomer , diimine , chemistry , ligand (biochemistry) , denticity , oxazoline , spectroscopy , atropisomer , infrared spectroscopy , nuclear magnetic resonance spectroscopy , stereochemistry , medicinal chemistry , photochemistry , computational chemistry , crystallography , catalysis , organic chemistry , crystal structure , biochemistry , receptor , physics , quantum mechanics
Bis(oxazoline)s (BOXs) are a privileged ligand class and have found widespread use in catalysis. Herein, the tautomerism of selected BOX ligands was evidenced by X‐ray diffractometry as well as by NMR and IR spectroscopy and supported by DFT calculations. In CDCl 3 solution at room temperature, the new 1,1‐bis(4,4‐dimethyl‐1,3‐oxazolin‐2‐yl)‐1‐phenylmethane ( Ph,H BOX‐Me 2 ) ligand is present as a 1:1 mixture of the diimine and iminoenamine tautomers. Thermodynamic and kinetic data for the tautomeric equilibrium were determined, which allowed comparison with related bidentate ligand classes. The other BOXs studied, H,H BOX‐Me 2 , Me,H BOX‐Me 2 , and t Bu,H BOX‐Me 2 , are largely present in the diimine form under similar conditions. IR spectroscopy was identified as a valuable tool for detecting the presence of the iminoenamine form as a minor component.