Metal-Free Synthesis of 1,2,4-Triazines via a Coupled Domino Process in One-Pot

Author(s): Jing Wang, Dong Tang, Zhuo-Mei Li, Ping Wu, Xu Meng, Ya-Feng Liu, Guo-Qiang Lu, Bao-Hua Chen.

Journal Name: Current Organic Chemistry

Volume 21 , Issue 2 , 2017

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Abstract:

Background: 1,2,4-Triazine is a prominent structural core system present in numerous natural and synthetic biologically active compounds. The existing synthetic methodologies have mostly focused on 3,6- disubstituted-1,2,4-triazines and 3,5,6-trisubstituted-1,2,4-triazines. However, until now only a few methods have been developed for making 3,5-disubstituted-1,2,4-triazines.

Objective: The primary objective of the study was to find an efficient and simple way to construct 3,5- disubstituted-1,2,4-triazines.

Method: The arylethene (0.24 mmol), I2 (0.22 mmol), IBX(0.24mmol.) and DMSO (2 mL) were added to a round-bottomed flask equipped with a magnetic stirring bar. The reaction mixture was agitated at 110°C under air for 3h, then amidrazone (0.2 mmol) was added to the mixture and the reaction continued at 110°C for another 1.5h. Afterwards, water (20mL) was added and the reaction mixture was extracted with ethyl acetate (3 × 50mL). The organic phases was combined and concentrated under reduced pressure to distill ethyl acetate. The residue was further purified by column chromatography on a silica gel column with petroleum / ethyl acetate (5:1) as eluent to obtain the desired products.

Results: We developed an operationally simple way of regioselectively synthesizing 3,5-disubstituted-1,2,4- triazines by a coupled domino strategy with terminal aryl alkenes and amidrazones in one-pot. The overall process involves three different reactions: iodination, Kornblum oxidation and condensation.

Conclusion: The strategies exhibit high performance with moderate to high yields, using simple and readily available terminal aryl alkenes and amidrazones, representing a powerful tool for the formation of potentially biologically active derivatives.

Keywords: 1, 2, 4-Triazines, domino strategy, aryl alkenes, amidrazones, Kornblum oxidation, metal-free.

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Article Details

VOLUME: 21
ISSUE: 2
Year: 2017
Page: [183 - 188]
Pages: 6
DOI: 10.2174/1385272820666160919113406
Price: $58

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