Studies Toward Tandem Cyclization Of Ortho-quinone Methides

ortho-Quinone methides(o-QMs)are highly reactive and shortlived species involved in a wide range of organic synthesis,biology and medicinal chemistry.Structurally,these powerful building blocks can be regarded as an active ?,?-unsatu-rated conjugated enone system.Based on the intrinsic electrophilic nature of o-QMs,a wide range of carboncentred nucleophiles and polarized dienophiles were employed in the 1,4-conjugate addition,[4 + n]-cycloaddition and 6? electrocyclization reactions with o-QMs to form C-C bonds.This dissertation is mainly based on the efficient reactivity,diverse reaction types and mild reaction conditions of ortho-Quinone methides,mainly including the following aspects: 1)Summarize the current situation of o-QMs,reactivity and its application in tandem,and briefly describe the background and significance of this work;2)Explain the research content of Lewis Acid-Catalyzed Tandem 1,4-Conjugate Addition/Cyclization of in Situ Generated Alkynyl ortho-Quinone Methides and Electron-Rich Phenols: Synthesis of Dioxabicyclo[3.3.1]nonane Skeletons.In this work,the substrate was expanded by a simple and gentle method after optimizing the conditions,and 28 examples were obtained with a yield of up to96%,and the stability of the process was verified by the gram-grade reaction.;3)Describe the research status of C-X(X = O,N,S,P)bond with ortho-Quinone methides and nucleophilic reagent,then summarize the process of Lewis acidcatalyzed tandem cyclization of in situ generated ortho-Quinone methides and arylsulfonyl hydrazides for a one-pot entry to 3-sulfonylbenzofurans.A series of functional benzofuran derivatives were obtained,and the application research of the reaction strategy was explored;4)Summarizes the experiment process and the data.