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Synthetic method of visible light mediated dihydroisoxazole

A technology of dihydroisoxazole and synthesis method, applied in the direction of organic chemistry, etc., can solve the problems of limited substrate range and severe reaction conditions, and achieve the effect of low price and mild conditions

Pending Publication Date: 2022-07-22
HENAN UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In summary, in the current reports on the direct synthesis of isoxazoles from simple and easy-to-obtain substrates, there are still problems such as limited substrate scope and severe reaction conditions.

Method used

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  • Synthetic method of visible light mediated dihydroisoxazole
  • Synthetic method of visible light mediated dihydroisoxazole
  • Synthetic method of visible light mediated dihydroisoxazole

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Example 1 Synthesis of 3-phenylisoxazole-5,5(4H)-diethyl carboxylate

[0028]

[0029] To a 10 mL Schlenk tube equipped with a stir bar was added styrene (0.2 mmol), diethyl dibromomalonate (0.48 mmol, 153 mg), fac-Ir (ppy) 3 (0.01 mmol, 6 mg), DMF (1 mL), DMAP (0.6 mmol, 73 mg) and tert-butyl nitrite (0.4 mmol, 41 mg). The Schlenk tube was evacuated and replaced 3 times with argon, then screwed on. The reaction mixture was subjected to visible light LED (λ max = 465 nm) under irradiation with stirring for 12 hours. The solvent was evaporated in vacuo and the residue was purified by flash column chromatography eluting with petroleum ether and ethyl acetate (5:1) to give the desired product in 79% yield.

[0030] H NMR spectrum of the product 3-phenylisoxazole-5,5(4H)-diethyl carboxylate: 1 H NMR (400MHz, CDCl 3 )δ7.80–7.57(m,2H),7.50–7.32(m,3H),4.44–4.18(m,4H),3.98(s,2H),1.33(,J=7.1Hz,6H).

[0031] Carbon spectrum: 13 C NMR (100MHz, CDCl 3 )δ167.2,155.8,130.7...

Embodiment 2

[0032] Example 2 Synthesis of 3-(p-tolyl)isoxazole-5,5(4H)-diethyl carboxylate

[0033]

[0034] To a 10 mL Schlenk tube equipped with a stir bar was added 4-methylstyrene (0.2 mmol), diethyl dibromomalonate (0.48 mmol, 153 mg), fac-Ir (ppy) 3 (0.01 mmol, 6 mg), DMF (1 mL), DMAP (0.6 mmol, 73 mg) and tert-butyl nitrite (0.4 mmol, 41 mg). The Schlenk tube was evacuated and replaced 3 times with argon, then screwed on. The reaction mixture was subjected to visible light LED (λ max = 465 nm) under irradiation with stirring for 12 hours. The solvent was evaporated in vacuo and the residue was purified by flash column chromatography eluting with petroleum ether and ethyl acetate (5:1) to give the desired product in 81% yield.

[0035] H NMR spectrum of the product 3-(p-tolyl)isoxazole-5,5(4H)-diethylcarboxylate: 1 H NMR (400MHz, CDCl 3 )δ7.55(d,J=8.2Hz,2H),7.20(d,J=8.0Hz,2H),4.39–4.22(m,4H),3.95(s,2H),2.37(s,3H), 1.31(,J=7.1Hz,6H).

[0036] Carbon spectrum: 13 C NMR (100...

Embodiment 3

[0037] Example 3 Synthesis of 3-(4-methoxyphenyl)isoxazole-5,5(4H)-diethyl carboxylate

[0038]

[0039] To a 10 mL Schlenk tube equipped with a stir bar was added 4-methylstyrene (0.2 mmol), diethyl dibromomalonate (0.48 mmol, 153 mg), fac-Ir (ppy) 3(0.01 mmol, 6 mg), DMF (1 mL), DMAP (0.6 mmol, 73 mg) and tert-butyl nitrite (0.4 mmol, 41 mg). The Schlenk tube was evacuated and replaced 3 times with argon, then screwed on. The reaction mixture was subjected to visible light LED (λ max = 465 nm) under irradiation with stirring for 12 hours. The solvent was evaporated in vacuo and the residue was purified by flash column chromatography eluting with petroleum ether and ethyl acetate (5:1) to give the desired product in 81% yield.

[0040] H NMR spectrum of the product 3-(4-methoxyphenyl)isoxazole-5,5(4H)-diethylcarboxylate: 1 H NMR (400MHz, CDCl 3 )δ7.58(d,J=8.8Hz,2H),6.89(d,J=8.8Hz,2H),4.36–4.22(m,4H),3.92(s,2H),3.80(s,3H), 1.29(,J=7.1Hz,6H).

[0041] Carbon spectrum:...

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Abstract

The invention belongs to the technical field of compound preparation, and particularly relates to a visible light mediated dihydroisoxazole synthesis method. Comprising the following steps: taking terminal olefin, a dibromomalonic acid compound and tert-butyl nitrite as raw materials, and carrying out cascade cyclization reaction in a solvent under the actions of argon protection, visible light, a photosensitizer and alkali to synthesize the dihydroisoxazole compound. The method is an effective method for constructing dihydroisoxazole through [2 + 2 + 1] intermolecular cyclization, the conditions are mild, and the three raw materials are easy to buy in the market and low in price.

Description

technical field [0001] The invention belongs to the technical field of compound preparation, in particular to a method for synthesizing dihydroisoxazole mediated by visible light. Background technique [0002] Dihydroisoxazoles are important structural motifs ubiquitously present in biologically active molecules, drugs and chiral ligands, and are also multifunctional intermediates in organic synthesis. Despite significant achievements to date, reported methods have limited substrate scope, especially in terms of functional group diversity. Therefore, the development of efficient methods to construct diverse dihydroisoxazoles has received increasing attention. [0003] In 2015, Xu Bin's group reported a method for the regioselective synthesis of polysubstituted dihydroisoxazoles through copper-mediated direct conversion of terminal alkynes and common alkenes. The authors believed that nitrile oxides were produced in the reaction system. intermediate and copper nitrate as a ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D261/04
CPCC07D261/04
Inventor 李盼赵静静刘九鹏
Owner HENAN UNIVERSITY
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