Because a catalyst decreases the height of the energy barrier, 538-58-9, its presence increases the reaction rates of both the forward and the reverse reactions by the same amount.538-58-9, Name is 1,5-Diphenylpenta-1,4-dien-3-one, molecular formula is C17H14O. In a article£¬once mentioned of 538-58-9
Catalytic asymmetric synthesis of spirocyclic azlactones by a double Michael-addition approach
Spirocyclic azlactones are shown to be useful precursors of cyclic quaternary amino acids, such as the constrained cyclohexane analogues of phenylalanine. These compounds are of interest as building blocks for the synthesis of artificial peptide analogues with controlled folds in the peptide backbone. They were prepared in the present study by a step- and atom-economic catalytic asymmetric tandem approach, requiring two steps starting from N-benzoyl glycine and divinylketones. The key of this protocol is the enantioselective formation of the azlactone spirocycles, which involves a PdII-catalyzed double 1,4-addition of an in situ generated azlactone intermediate to the dienone (a formal [5+1] cycloaddition). As the catalyst, a planar chiral ferrocene bispalladacycle was used. Mechanistic studies suggest a monometallic reaction pathway. Although the diastereoselectivity was found to be moderate, the enantioselectivity is usually high for the formation of the azlactone spirocycles, which contain up to three contiguous stereocenters. Spectroscopic studies have shown that the spirocycles often prefer a twist over a chair conformation of the cyclohexanone moiety. A formal [5+1] cycloaddition of divinylketones and an in situ-generated glycine-derived azlactone was catalyzed by a chiral bis-palladacycle and provided highly enantioenriched, spirocyclic, masked amino acid products. The latter were used to synthesize biologically interesting constrained cyclohexane analogues of phenylalanine in just two steps (see scheme). Copyright
A reaction mechanism is the microscopic path by which reactants are transformed into products. Each step is an elementary reaction. 538-58-9, In my other articles, you can also check out more blogs about 538-58-9
Reference£º
Synthesis and Crystal Structure of a Chiral?C3-Symmetric Oxygen Tripodal Ligand and Its Applications to Asymmetric Catalysis,
Chiral lanthanide(III) complexes of sulphur¨Cnitrogen¨Coxygen ligand derived from aminothiourea and sodium?D-camphor-¦Â-sulfonate