CN-120608293-B - Electrosynthesis method of 1-pyrroline

CN120608293BCN 120608293 BCN120608293 BCN 120608293BCN-120608293-B

Abstract

The invention discloses an electrosynthesis method of 1-pyrroline, which comprises the steps of preparing 1-pyrroline derivatives by using a platinum sheet as a cathode and a carbon rod as an anode and tetrabutylammonium perchlorate or tetrabutylammonium tetrafluoroborate as an electrolyte under constant current catalysis and dimerization cyclization of styrene and azido trimethylsilane by a one-pot method, and obtaining a 1-pyrroline pure product by column chromatography separation after post-treatment of the obtained reaction mixture. The invention can obtain the 1-pyrroline derivative by one-step reaction, has few operation steps, avoids using oxidant, additive and metal, has simple post-treatment process and is easy to separate products.

Inventors

ZHANG CHONG
SONG BIN
GAO CHAO
HU BINGCHENG
CHEN LEI
PANG LIN

Assignees

南京理工大学

Dates

Publication Date: 20260512
Application Date: 20250723

Claims (13)

1. A method for preparing 1-pyrroline is characterized by comprising the steps of carrying out electrochemical reaction on R-substituted styrene and azido trimethylsilane in electrolyte solution to synthesize a target product: ; Wherein R is any one group of methyl, ethyl, tertiary butyl, alkoxy, chloromethyl, halogen and trifluoromethyl, and the substitution position is ortho-position, para-position or meta-position; the solvent in the electrolyte solution is a mixed solvent of dichloroethane and hexafluoroisopropanol with the volume ratio of 5-10:1; the electrochemical reaction adopts constant current, and the current is 3-20 milliamperes.
2. The method of claim 1, wherein the electrolyte in the electrolyte solution is tetrabutylammonium perchlorate or tetrabutylammonium tetrafluoroborate.
3. The method of claim 1, wherein the solvent in the electrolyte solution is a mixed solvent of 8:1 dichloroethane and hexafluoroisopropanol.
4. The method of claim 1, wherein the electrochemical reaction uses a carbon rod as the anode and a platinum sheet as the cathode.
5. The method of claim 1, wherein the current is 3 milliamps to 10 milliamps.
6. The method of claim 1 or 5, wherein the current is 5 milliamps.
7. The method of claim 1, wherein the electrochemical reaction is performed at 0-40 ℃.
8. The method of claim 1 or 7, wherein the electrochemical reaction is performed at room temperature.
9. The method of claim 1, wherein the electrochemical reaction time is not less than 6 hours.
10. The method of claim 1, wherein the electrolyte is present in an amount of 0.2 to 1 times the amount of the R-substituted styrene.
11. The method of claim 1 or 10, wherein the electrolyte is present in an amount of 0.5 times the amount of R-substituted styrene.
12. The method of claim 1, wherein the amount of azido trimethylsilane is 1 to 3 times the molar amount of R-substituted styrene.
13. The method of claim 1 or 12, wherein the amount of azido trimethylsilane is 1.5 times the molar amount of R-substituted styrene.

Description

Electrosynthesis method of 1-pyrroline Technical Field The invention belongs to the field of organic chemical synthesis, and particularly relates to a method for preparing 1-pyrroline. Background The 1-pyrroline derivative is an organic synthesis intermediate with various biological activities and has wide application in the fields of chemistry, materials and drug design. To date, classical 5-exo-trig cyclization reactions still provide powerful support for the synthesis of 1-pyrroline derivatives, in which metals, oxidants and other catalysts are required to effect the formation of nitrogen radicals or nitrogen metal complexes, thereby effecting the addition of olefins, which requires not only complex pre-synthesis of the substrate, but also the completion of cyclization of another molecule. Thus, the preparation of 1-pyrroline derivatives from simple substrates and conditions is necessary. In addition, current electrochemical organic synthesis techniques exhibit excellent synthesis capabilities, and are increasingly attracting interest in organic works. The technology can solve the problems of low yield and the like caused by the use of additives and external oxidants, can be simply operated under mild conditions, and can finish the starting and stopping of experiments along with the control of current. Therefore, the searching of a green and efficient method for electrosynthesis of 1-pyrroline derivatives is an important research content. Disclosure of Invention The invention aims to provide a simple and convenient method for preparing 1-pyrroline derivatives from styrene and azido trimethylsilane in a green and efficient way. The technical scheme for realizing the aim of the invention is as follows: In a first aspect, the invention provides a method for preparing 1-pyrroline, comprising the steps of carrying out electrochemical reaction on styrene and azido trimethylsilane in an electrolyte solution to synthesize a target product: Wherein R includes, but is not limited to, any of methyl, ethyl, t-butyl, alkoxy, chloromethyl, halogen, trifluoromethyl, and the substitution position may be ortho, para, or meta. Further, the electrolyte in the electrolyte solution is tetrabutylammonium perchlorate or tetrabutylammonium tetrafluoroborate, and the solvent is a mixed solvent of dichloroethane and hexafluoroisopropanol in a volume ratio of 5-10:1, preferably 8:1. Further, the electrochemical reaction adopts a carbon rod as an anode, a platinum sheet as a cathode, and the current is constant current of 3-20 milliamperes, preferably constant current of 3-10 milliamperes, and more preferably constant current of 5 milliamperes. Further, the electrochemical reaction is carried out at 0-40 ℃, preferably at room temperature. Further, the electrochemical reaction time is not less than 6 hours. Further, the electrolyte is used in an amount of 0.2 to 1 times, preferably 0.5 times the molar ratio of the styrene. Further, the amount of azido trimethylsilane is 1 to 3 times, preferably 1.5 times, the molar ratio of the amount of styrene. Further, the raw materials and the electrolyte are added under the protection of inert gas, preferably argon. Compared with the prior art, the invention has the remarkable advantages that: (1) The synthesis method is simple and efficient, the 1-pyrroline derivative can be obtained through one-step reaction, the operation steps are few, the use of an oxidant and an additive is avoided, the post-treatment process is simple, the product is easy to separate, and the operation requirement is greatly simplified; (2) The reaction condition of the invention is easy to realize, and the invention does not need harsh conditions such as low temperature, high temperature, illumination, pressure, strong acid and alkali, etc., thus avoiding special requirements of biocatalysis, noble metal catalysis, etc.; (3) The styrenes used in the present invention exhibit excellent reactivity under electrochemical conditions, and cyclization with azido trimethylsilane after dimerization is a known simple method for synthesizing 1-pyrroline derivatives from the most readily available starting materials. Drawings FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of 2, 5-diphenyl-3, 4-dihydro-2H-pyrrole prepared in example 1 of the present invention. FIG. 2 is a nuclear magnetic resonance carbon spectrum of 2, 5-diphenyl-3, 4-dihydro-2H-pyrrole prepared in example 1 of the present invention. FIG. 3 is a nuclear magnetic resonance hydrogen spectrum of 2, 5-bis (4-isopropoxyphenyl) -3, 4-dihydro-2H-pyrrole prepared in example 2 of the present invention. FIG. 4 is a nuclear magnetic resonance carbon spectrum of 2, 5-bis (4-isopropoxyphenyl) -3, 4-dihydro-2H-pyrrole prepared in example 2 of the present invention. FIG. 5 is a nuclear magnetic resonance hydrogen spectrum of 2, 5-di-o-tolyl-3, 4-dihydro-2H-pyrrole prepared in example 3 according to the present invention. FIG. 6 is a nuclear magnetic resonance carbon spe