| Abstract
| - E- and Z-nitroolefins were used as Michael acceptors in 1,4-conjugate addition of chiral Fischer-type aminocarbene complexes. The resulting adducts, precursors of β-aryl-γ-butyric acid derivatives, were obtained with high chemical yield and modest to good diastereoselectivity. Theoretical calculations were performed to rationalize the stereochemical outcome of the reactions and to support the proposed transition state models.
- The anions of the pentacarbonyl(chromium) trans-2,6-dimethylmorpholinyl(methyl)carbeneand pentacarbonyl(chromium) trans-3,5-dimethylpiperidinyl(methyl)carbene complexes addedto E- and Z-nitrostyrenes through a diastereoselective Michael-type reaction to giveprecursors of β-aryl-γ-butyric acid derivatives. The diastereoselectivity observed with theformer carbene was dependent on the nature of the substituent present in the 4-position ofnitrostyrenes and was higher when it was an electron-withdrawing group. The presence of12-crown-4 ether in the reaction medium increased both reaction times and diastereoselectivity. Theoretical calculations were performed to rationalize the stereochemical outcomesof the reactions and to support the proposed transition state models.
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