Synthesis Of Indole Skeleton-containing Allene Molecules By Azacarbene-catalyzed δ-LUMO Activation Of Enyne Aldehyde

As a special structural unit,diene skeleton derivatives are commonly used in various natural products,pharmaceuticals,pesticides,and fine chemical synthesis intermediates.Due to its unique biological activities and extensive practicality,it has attracted widespread attention in the field of organic synthesis.How to construct this important compound through simple,efficient,and green synthesis methods has been the focus of research in the field of organic catalysis.As an indispensable class of organic small molecule catalysts in organic asymmetric catalysis,N-Heterocyclic Carbene(NHC)play an important role in green environmental protection research in the field of chemistry due to their stable properties and simple after-treatment.It controls the activation ability of carbon atoms at different sites through different activation modes,thereby replacing traditional metal catalysts to obtain corresponding new skeleton compounds.In this article,alkynyl aldehyde and 3-fluoroindole derivatives undergo an addition reaction via remote activation of NHC to obtain diene derivatives containing a 3-fluoroindole skeleton in one step.The follow-up mechanism and application research have been conducted.This article mainly focuses on the following three aspects:Part Ⅰ: Emphasis on the introduction of the research status of NHC and diene molecules in the field of organic synthesis.On the one hand,the classical reactions of NHC to different activation sites in the substrate,such as carbonyl carbon,α-carbon,β-carbon,γ-carbon,δ-carbon,are summarized.On the other hand,the methods of synthesizing diene molecules through different catalytic systems are mainly summarized.The results showed that: there are few studies on the δ-carbon remote activation of alkynyl aldehyde using NHC,mainly focusing on the remote activation of unsaturated dialdehydes.Part Ⅱ: Emphasis on the introduction of the purpose and significance of carrying out this topic.Based on the review and summary of the above literatures,it is found that diene skeletons are commonly used in the fields of pesticides such as antibacterial and antiviral drugs,in the pharmaceutical fields such as anti-tumor and chromotherapy,and also in modern industries such as dyes and additives.Due to the increasingly prominent research value of diene molecules in the field of organic synthesis,how to easily and efficiently prepare diene compounds has become an important topic explored by researchers.Part III: Emphasis on the introduction of the addition reaction between the alkynylaldehyde and 3-fluoroindole derivative through the remote activation of NHC to obtain diene derivatives containing a 3-fluoroindole skeleton.After determining the model reaction,a series of reaction reagents such as nucleophilic reagents,catalysts,solvents,and bases were screened for conditions.Under the optimal reaction conditions,the universal range of the reaction,the scale-up reaction,and the application of the target product were explored.