RESUMO
[reaction: see text] The first asymmetric aminohalogenation of functionalized alkenes has been established. The ionic liquid [bmim][BF4] was found to be the only effective media for success as normal organic solvents failed to give any product for this reaction. The reaction is also very convenient to perform by simply mixing the three reactants, cinnamates, N,N-dichloro-p-toluenesulfonamide, and catalyst, together with 4 A molecular sieves at room temperature in [bmim][BF4] in any convenient vial of appropriate size without special protection from inert gases. Good chemical yields (60-72%) and diastereoselectivities (up to 75% de) have been obtained with a good scope of substrates. The resulting individual diastereomers have been cleanly separated via column chromatography. The absolute stereochemistry of the reaction was unambiguously determined by X-ray structural analysis.
Assuntos
Alcenos/síntese química , Halogênios/química , Alcenos/química , Aminação , Cristalografia por Raios X , Modelos Moleculares , Conformação Molecular , EstereoisomerismoRESUMO
The first multiple-site activation of alkynes with amine/halogen functionalities has been established. The reaction was performed by treating alkyne with N,N-dichlorobenzenesulfonamide at 80 degrees C in the presence of palladium acetate catalyst. A new mechanism was proposed which involves the novel formation of beta-halovinyl palladium and pi-allylpalladium species. Excellent regio- and stereoselectivities were achieved with the absolute structure determined by X-ray structural analysis.