Search

α,β‐Unsaturated compounds are one of the most important functional compounds. Due to their unique property and versatile utility, they usually occur as the key intermediates for the synthesis of pharmaceuticals and biological materials. Thus, their synthesis has attracted more attentions than before. The early approaches to α,β‐unsaturated compounds are mainly about transition‐metal‐free methods, such as halogenation‐dehydrohalogenation methods and strong oxidants methods (organosulfur, organoselenium, benzoquinone). Subsequently, palladium and the other transition‐metals catalyzed dehydrogenation of carbonyl compounds appeared respectively. In this review, transition‐metal‐catalyzed α,β‐dehydrogenation is discussed, which is categorized by functional groups. [ABSTRACT FROM AUTHOR]

The combinations of N-methyl- p-toluenesulfonamide/NBS and N-ethyl- p-toluenesulfonamide/NBS were found to be good nitrogen/halogen resources for the aminohalogenation of α,β-unsaturated ketones in the presence of Ni(OAc)2 as the catalyst for the synthesis of vicinal haloamino ketone derivatives. The introduction of N-alkyl groups to the nitrogen resources resulted in excellent regio- and stereoselectivity for both electron-donating and electron-withdrawing group-attached unsaturated ketone substrates. The structure of the resulting products has been unambiguously confirmed by X-ray crystal structure analysis. [ABSTRACT FROM AUTHOR]