CN-122010777-A - Method for synthesizing cyclopentane compounds by utilizing bromide ions/visible light synergistic catalysis

Abstract

The invention relates to the technical field of organic synthesis, in particular to a method for synthesizing cyclopentane compounds by catalyzing [3+2] cycloaddition reaction of aryl cyclopropane and olefin in a synergic manner by bromide ions/visible light. In the method, aryl cyclopropane, a benzyl allyl dinitrile derivative, pyridine tribromide and a photocatalyst are sequentially added into a reaction solvent under the nitrogen atmosphere to obtain a mixture, the mixture is stirred under the irradiation of a blue light LED lamp with the temperature of 40 ℃ and the wavelength of 12W until the reaction is complete, and the cyclopentane compounds can be obtained through concentration and column chromatography purification. The method has the advantages of mild reaction conditions, simple and convenient operation, simple and easily obtained raw materials and low cost.

Inventors

• FENG CHAO
• ZHANG CHI
• WU MENGYU

Assignees

• 南京工业大学

Dates

Publication Date

20260512

Application Date

20260210

Claims (3)

1. 1. A preparation method of cyclopentane compounds is characterized in that under the synergistic catalysis of a bromide ion catalyst and a photocatalyst, aryl cyclopropane and olefin undergo [3+2] cycloaddition reaction under blue light irradiation to obtain cyclopentane compounds; Wherein the structure of the aryl cyclopropane is shown as a formula 1, The structure of the olefin is shown in a formula 2, The structure of the cyclopentane compound is shown as a formula 3, Ar 1 in formula 1 and formula 3 is selected from any one of 4-methoxyphenyl, 2-methoxyphenyl, 4-phenylphenyl, 2-naphthyl, 4-tert-butylphenyl, 3-fluoro-4-methoxyphenyl, benzodihydrofuran-4-onyl, dibenzofuran-2-yl, 6-benzothienyl, 4-trimethylsilylphenyl, 4-carbamic acid tert-butylphenyl, 4-methylpropanoylphenyl, 3-methyl-4-methoxyphenyl, 2, 3-dihydrobenzo [ b ] [1,4] dioxane, 4-phenylacetate; Ar 2 in the formulae 2 and 3 is selected from any one of phenyl, 4-phenylphenyl, 3-benzoylphenyl, 4-chlorophenyl, 4-bromophenyl, 4-methoxyphenyl, 4-fluorophenyl, 4-cyanophenyl; The bromide ion catalyst is pyridine tribromide; the photocatalyst is 3, 6-di-tert-butyl-9-mesityl-10-phenylacridine-10-onium tetrafluoroborate.
2. 2. The method for preparing cyclopentane-based compound according to claim 1, characterized in that it comprises the following steps: (1) Under the nitrogen atmosphere, sequentially adding aryl cyclopropane 1, olefin 2, a bromide ion catalyst and a photocatalyst into a reaction solvent to obtain a mixture; wherein the mole ratio of the aryl cyclopropane 1, the olefin 2 and the bromide ion catalyst to the photocatalyst is 1.5:1:0.02:0.02; (2) And (3) stirring the mixture obtained in the step (1) at a proper temperature under the irradiation of a blue LED lamp until the reaction is complete. Concentrating and purifying the crude reaction product by column chromatography to obtain cyclopentane compounds; wherein the mixture is stirred and reacted for 20 hours at 40 ℃, the wavelength of a blue light lamp is 456nm, and the power is 12W.
3. 3. The method for producing cyclopentane-based compound according to claim 2, wherein in step (1), the reaction solvent is acetonitrile.

Description

Method for synthesizing cyclopentane compounds by utilizing bromide ions/visible light synergistic catalysis Technical Field The invention relates to the technical field of organic synthesis, in particular to a method for preparing substituted cyclopentane compounds by ring-opening [3+2] cycloaddition reaction of aryl cyclopropane and olefin under the synergistic catalysis of bromide ion and photooxidation reduction. Background Cyclopropane compounds are widely found in natural products and synthetic chemical entities with biological activity, which makes them an advantageous structure in the development of pharmaceuticals and agrochemicals. In addition, cyclopropane compounds have unique chemical bond structures and high ring tensions, so that ring cleavage and subsequent further functionalization can occur under specific conditions. Cyclopropane, as a versatile chemical building block in modern organic synthesis, can undergo various types of ring-opening functionalization reactions, which are one of the hot spot directions of research. Currently there are mainly the following strategies for the cycloaddition of cyclopropane ring opening to olefins. First, in the method disclosed in document 1 (H.Xiong, H.Xu, S.Liao, Z.Xie, Y.Tang.J am. Chem. Soc.2013,135, 7851-7854), cyclopropane having an electron-donating-electron-withdrawing group is used to perform a [3+2] cycloaddition reaction with indole by Lewis acid activation, and the specific reaction procedure is as follows: Secondly, in the method disclosed in document 2 (A.G.Amador, E.M.Sherbrook, T.P.Yoon.J.Am.Chem.Soc.2016,138,4722-4725), cyclopropyl ketone is taken as a raw material, cycloaddition reaction is carried out with olefin under the synergistic catalysis of a photocatalyst and Lewis acid, and the specific reaction process is as follows: Thirdly, in the method disclosed in document 3 (S.Maity, M.Zhu, R.S.Shinabery, N.Zheng.Angew.Chem.Int.Ed.,2012,51,222-226), cyclopropylamine is used as a raw material, and cycloaddition reaction is performed with olefin under the condition of photocatalytic oxidation, and the specific reaction process is as follows: Fourth, in the method disclosed in document 4 (q.—q.zhao, x.—s.zhou, s.—h.xu, y.—l.wu, w.—j.xiao, j.—r.chen.org. lett.2020,22, 2470-2475.) an alkenyl cyclopropane is used as a starting material to undergo a cycloaddition reaction with an olefin under photocatalytic conditions, the specific reaction process is as follows: However, the above strategies all require an activating group (ester group, carbonyl group, amine group, alkenyl group, etc.) attached to the cyclopropane, and the reaction is generally applicable to electron-rich olefins, greatly limiting the application of the cyclopropane to the construction of cyclopentane derivatives by cycloaddition reaction of cyclopropane with olefins [3+2 ]. Therefore, it is important to develop a more versatile and efficient process to achieve cycloaddition reactions of other types of non-activated cyclopropanes. Disclosure of Invention The invention aims to provide a preparation method of cyclopentane derivatives with mild conditions and simple operation by utilizing a 3+2 cycloaddition reaction of bromide ions/visible light synergistic catalysis aryl cyclopropane and olefin, and aims to solve the difficulties of limited types of cyclopropane and olefin substrates and the like in the existing method. The scheme adopted by the invention for realizing the purpose comprises the following steps of sequentially adding aryl cyclopropane, olefin, bromide ion catalyst and photocatalyst into a reaction solvent under the nitrogen atmosphere to obtain a mixture, stirring the mixture at a proper temperature under the irradiation of a blue light LED lamp until the reaction is complete, and obtaining the cyclopentane compound through concentration and column chromatography purification. The reaction scheme of the method of the invention can be represented as follows: formula 1 represents arylcyclopropane, formula 2 represents olefin, and formula 3 represents cyclopentane compound. Ar 1 in formula 1 and formula 3 is selected from any one of 4-methoxyphenyl, 2-methoxyphenyl, 4-phenylphenyl, 2-naphthyl, 4-tert-butylphenyl, 3-fluoro-4-methoxyphenyl, benzodihydrofuran-4-onyl, dibenzofuran-2-yl, 6-benzothienyl, 4-trimethylsilylphenyl, 4-carbamic acid tert-butylphenyl, 4-methylpropanoylphenyl, 3-methyl-4-methoxyphenyl, 2, 3-dihydrobenzo [ b ] [1,4] dioxane, 4-phenylacetate; Ar 2 in the formulae 2 and 3 is selected from any one of phenyl, 4-phenylphenyl, 3-benzoylphenyl, 4-chlorophenyl, 4-bromophenyl, 4-methoxyphenyl, 4-fluorophenyl, 4-cyanophenyl; The bromide ion catalyst is pyridine tribromide; the photocatalyst is 3, 6-di-tert-butyl-9-mesityl-10-phenylacridine-10-onium tetrafluoroborate. The reaction solvent is one of tetrahydrofuran, dichloromethane and acetonitrile, preferably acetonitrile, and the concentration of the reaction mixture is 0.1M-1.0M, preferably 0.2M; the mol