Based On The Alkenylation And Bifunctionalization Of Aromatic Carboxylic Acids

The development of carbon-carbon bond construction methods is one of the important research contents in modern organic synthesis.The traditional carbon-carbon coupling reaction plays an important role in constructing new structures and functional organic molecules,but it also has many defects such as many by-products,poor atomic economy,long synthetic steps,high reaction costs,and large environmental pollution.Therefore,the development of efficient and highly selective synthesis methods from simple and readily available compounds has become a research area in organic synthetic chemistry.The directing group assisted C-H bond functionalization catalyzed by transition metal avoids the use of halogenated substances.Thus,it shortens the reaction step,reduces the environmental pollution,and improves the efficiency of the reaction.The directing group assisted C-H bond functionalization provides a new pathway for the synthesis of complex molecular.Carboxyl group is widely present in organic and natural products.It can be readily obtained from many other functional groups.After the functionalization of the C-H bond,the carboxyl group can be facilely converted to different functional groups or removed by decarboxylation.Carboxylic acids used as directing group have been attracted much attention.Vinylarenes are ubiquitous motifs found in numerous natural products and organic materials,and are widely used as key intermediates in many organic transformations.Moreover,many polysubstituted aromatics not only have remarkable biological activities,but also are precursors for the synthesis of fused-ring compounds.Based on these,this dissertation mainly focuses on the following aspects.In the first chapter,the research progress of the carboxyl-directed C-H bond functionalization about cross dehydrogenation coupling and one-step synthesis of polysubstituted aromatics is reviewed.In the second chapter,a rhodium-catalyzed ortho-olefination of aromatic acids with acrylates has been developed for the synthesis of a wide range of ortho-olefinated free aromatic acids in good to excellent yields.The reaction undergoes a removable carboxyl-directed cross-dehydrogenative coupling.Employing simple and readily available starting materials,this process is successfully realized under mild reaction conditions without any additives.Additional features of the method are broad substrate scope and shorter reaction time.In the third chapter,when toluic acid reacted with methyl acrylate in the presence of[RuCl2(p-cymene)]2 as catalyst,Ag2CO3 as oxidant,Cu2O as additive,1,4-dioxane as solvent,alkylated-alkenylated benzene could be obtained in one step.The reaction underwent carboxyl-directed ortho-alkylation/alkenylation,and subsequent in-situ decarboxyalkenylation/alkylation.However,the reaction is still need to be optimized to achieve a better conversion and selectivity.In the last chapter,the innovation of this work was summarized.