A kind of synthetic method of 2-substituted indole derivatives

Abstract

The present invention relates to a kind of synthetic method of preparing 2-substituted indole derivatives, aromatic amine compound (I), ketone compound (II) and desiccant are mixed in organic solvent, after adding palladium catalyst, in aerobic Reaction under weakly acidic environment makes described indole compound (III), (I) is (II) is (III) is wherein R 1 selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 alkanoyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, hydroxyl, substituted or unsubstituted amino, substituted or unsubstituted phenyl, pyridyl and heterocyclic aryl; (1) also can be substituted or unsubstituted pyridinamine, pyrimidinamine, pyridazinamine or pyrazinamine; substituting group is selected from one or more C1-C6 alkyl, C1‑C6 alkoxy, C1‑C6 alkanoyl, C2‑C6 alkenyl, C2‑C6 alkynyl, halogen, hydroxyl, amino; R 2 Selected from C1-C6 alkyl group, formate group or C1-C6 alkanoyl amido group.

Description

technical field [0001] The invention relates to a method for directly preparing 2-substituted indole derivatives from aromatic amines under normal pressure. Background technique [0002] Indole is one of the most common aromatic heterocyclic structures and synthetic building blocks. It widely exists in natural products and human physiologically active substances. It is also an important structural unit commonly found in medicine and functional materials. It is called "dominant structure". ". In view of its importance in many fields, the synthesis of indoles and their functionalization methods have been continuously developed and improved since the last century. [0003] These synthesis methods can be roughly divided into two categories, namely equivalent reaction and catalytic reaction. There are many names whose reactions belong to the equivalent category, such as Bartoli, Mori-Ban and the famous Fischer indole synthesis method. These methods have their own limitations, ...

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Problems solved by technology

However, these methods still have the following limitations: 1. Most methods need to use a large amount of copper salt as an oxidant, which is uneconomical for large-scale synthesis and difficult to post-process; In the reaction to synthesize indole, a relatively stable imine or enamine needs to be synthesized first; 3. In order to obtain a stable imine or enamine intermediate, it is often necessary to introduce specific groups at the 2-position and 3-position of indole, Most of these groups are difficult to remove, which reduces the flexibility of retransformation or as a synthetic building block

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