Synthesis a Series of Substituted Triazine Compounds by the Suzuki Cross-coupling Reaction
|School||Dalian University of Technology|
|Keywords||Organic synthesis Palladium catalyst aryl boronic acid Suzuki cross-coupling Cyanuric chloride|
The palladium-catalyzed cross-coupling reaction is one of the important tools in the organic synthesis of carbon-carbon bonds. Suzuki coupling reaction between organoboron and aryl halides is a powerful and general methodology for the formation of aryl-aryl compounds. Due to the mild reaction conditions, low toxicity associated with boron compounds, good stability and tolerating a broad range of functional groups, the palladium-catalyzed Suzuki reaction has received great attention. Thus, a new and effective method has received much attention in synthetic triazine compounds because of direct introduction alkyl or aryl grounds on the triazine core by Suzuki cross-coupling. These methods have been repored, however, reports on this area is still in shortage, and these only reports lack thoroughly and systemically investigations. Therefore, it is significant to systematically and deeply study the Suzuki reaction of cyanuric chloride with varied substitutes. The main contents are as follow:1. Optimization of the reaction conditions of cyanuric chloride and organoboron synthesis of tri-substitued, disubstituted and mono-substituted.Frist:4-Methylphenylboronic acid and Cyanuric chloride as the model reaction synthesis tri-substitued and set up an initial reaction conditions, we investigated various factors that affect the reaction efficiency including catalyst, base, solvent, temperature and reaction time, and finally obtained an optimized conditions that is in air atmosphere, PdCl2(PPhs)2as catalyst, sodium hydroxide as base, allow the reaction in toluene(5mL), under110°C proceed1Omin with98%yield.Second:4-Methylphenylboronic acid and Cyanuric chloride as the model reaction synthesis di-substitued and set up an initial optimized reaction conditions that is in air atmosphere, PdCl2(PPh3)2as catalyst, sodium hydroxide as base, allow the reaction in toluene, under40°C proceed lh with92%yield. Then investigated various reaction temperature (40°C,60"C,80°C) that affect the reaction efficiency.Third:4-Methylphenylboronic acid and Cyanuric chloride as the model reaction synthesis mono-substited and set up an initial optimized reaction conditions that is in air atmosphere, PdCl2(PPh3)2(6mg) as catalyst, sodium hydroxide as base, allow the reaction in toluene, under40°C proceed lh with78%yield. We investigated various factors that affect the reaction efficiency including catalyst, solvent and temperature. 2. Under the optimized conditions we investigated the scope and limitations for various aryl bormides with cyanuric choloride synthesis tri-substited, disubstituted and monosubstituted. As for the aryl bromides containing electron-donating groups such as-CH3.-OCH3. good to excellent yields at the optimization of conditions. Mono-substitued triazine compounds in the yields of70%. As for the aryl bromides containing electron-withdrawing groups such as-F.-CF3,-CN, general yields at the optimization of conditions, di-substited and mono-substited triazine compounds to obtain low yield. Because the steric effect only made a low yield with2-OCH3groups. Overall, investigated the scope and limitations of this catalytic system has a good functional group tolerability with various aryl bormides.