Mixed-Ligand Arenechromium Carbonyl Complexes as Electronic Modulators
摘要:
A number of mixed ligand eta(6) arenechromium carbonyl complexes have been prepared and investigated for their ability to effect electronic modulation of arene chemistry. In the case of an aniline-derived system, the arenechromium carbonyl complex is able to modulate the inductive capacity of the aniline nitrogen atom and thus, regulate its anchimeric ability. In the case of 8-phenylmenthol and benzyloxazolidinone derivatives, modulation of arene ar basicity is achieved, and results suggest that important vinylarene pi-pi interactions exist in acrylate derivatives of these chiral auxiliary systems.
The chiral induction in the Diels-Alder addition 1 → 2, assessed reliably by 19F-NMR-spectroscopy of the endo-esters 4, varied between 47 - 93% in favor of the 2-(R)-adducts 2 depending on the auxiliary chiral group and the Lewis-acid catalyst.