Photocatalyzed Olefin Isomerization And Palladium Nanoparticles-Catalyzed Suzuki Coupling Reaction

As an important structural unit,olefins are widely exist in various natural products and bioactive molecules.However,established an efficient and operationally simple protocol to access thermodynamically less stable Z-alkenes remains a challenge.In the first part of this paper,a photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under visible light is disclosed.In this study,the reaction conditions such as photosensitizers,solvents,reaction temperature and light sources were investigated.This method provides scalable and efficient access to Z-cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity.Importantly,this method also provides a powerful strategy for the selective synthesis of Z-magnolol and honokiol derivatives possessing potential biological activity.Palladium-catalyzed Suzuki coupling is among the most important reactions for the formation of carbon-carbon bonds in organic transformations.However,palladium catalyst brings a high cost as well as significant efficiency,and much attention is recently focused on developing an effective catalytic system for the low catalyst loading.In the second part of this paper,a simple and highly efficient palladium nanoparticles catalytic system was applied in Suzuki coupling reaction.The reaction conditions such as base,solvents,reaction time and the amount of TBAB were investigated.This system could catalyze a variety of aryl halide and arylboronic acid substrates with a wide range of functional groups.A hight turnover numbers(TONs)for 90000 was obtained for p-nitrobromobenzene with the catalyst loading as low as 0.001 mol%.This catalyst system exhibits good stability and longevity.