Manganese / Iron Catalyzed Dehydrogenation Coupling Of Secondaryalcohols And Transfer Hydrogenation Of Alkynes

Olefins are commonly used as intermediates in organic reactions.They are found in a variety of bioactive natural products and drug molecules.Recently,the development of inexpensive metal catalytic systems,including iron,cobalt,nickel,manganese and copper,has led to the creation of numerous methods for producing olefins and olefin derivatives.The dehydrogenation coupling reaction of alcohols and transfer hydrogenation of alkynes are noteworthy research results in olefin synthesis.The former has become a research hotspot due to its production of only water or hydrogen by-products,making it advantageous for its’green’and high atomic economy properties.The transfer hydrogenation of alkynes,which features mild reaction conditions,high reaction conversion rates,and involvement of high-pressure reactors,has also attracted widespread attention.This method is particularly significant given the widespread use of olefins and their derivatives,highlighting the need for continuous development of novel and efficient olefin synthesis methods.In Chapter 2,we utilized PNP^Ph-Mn as a catalyst to facilitate the dehydrogenation coupling reaction between 1-tetrahydronaphthyl alcohol and cyclohexanol,ultimately resulting in the formation of tetrasubstituted olefin products.Through the screening of reaction conditions,we were able to achieve a high reaction yield.The mechanism experiment confirmed that the conversion of ketone intermediates generated by the raw materials was crucial to the success of the reaction.In this system,the raw materials are inexpensive and readily available,the reaction conditions are mild,environmentally friendly and low toxicity,and only produce H₂and H₂O as by-products.In Chapter 3,we studied the transfer semi-hydrogenation of alkynes catalyzed by iron compounds in heterogeneous systems.In this reaction,Fe Cl₂was used as a catalyst,Na BHEt₃was used as an activator,and ammonia borane was used as a hydrogen source to achieve alkyne transfer semi-hydrogenation reaction to prepare a series of Z-alkenes.The catalytic system exhibited good stability,excellent tolerance towards functional groups and exceptiaoal stereoselectivity（Z/E>98:2）.The mercury toxicity experiment demonstrated that the catalytic reaction occurred in a heterogeneous system.Additionally,X-ray diffraction（XRD）and Fourier transform infrared spectroscopy（FT-IR）was used to determine that the catalytic cycle of the system took place within the pore size of an amorphous iron powder particle.This method exhibits high atomic economy and meets the requirements of green chemistry development.This method provides an efficient and mild method for the transfer semi-hydrogenation of alkynes.The study of a low-cost iron catalyst provided not only offers a new research idea for the synthesis of other olefins,but also advances the exploration and development of heterogeneous iron catalytic reaction systems.