卤盐离子液体/氧气催化芳硫酚与异色满反应

Halogen salt ionic liquid/O_(2) catalyzed reaction of aromatic thiophenol and isochroman

以1-羧乙基-3-甲基咪唑氯盐([COOH-Et MIm][Cl])/O_(2)体系催化异色满与取代苯硫酚发生脱氢偶联反应,合成了1-(取代苯硫基)异色满。通过单因素实验对反应影响因素进行了筛选,得到适宜反应条件为:4-甲基苯硫酚(62 mg,0.5 mmol)、异色满(134 mg,1.0 mmol)、[COOH-EtMIm][Cl](95 mg,0.5 mmol)、O_(2)(0.10 MPa)、反应温度120℃、反应时间12 h。在该条件下,催化剂可使用4次,实现了1-(4-甲基苯硫基)异色满克级合成,底物拓展后得到12种1-(取代苯硫基)异色满,产率为52%~96%。提出了[COOH-Et MIm][Cl]阴阳离子通过氢键分别活化苯硫酚与异色满,经O_(2)氧化,脱氢得到1-(取代苯硫基)异色满的反应机理。

1-Substituted thiophenol isochromans were obtained via 1-carboxyethyl-3-methylimidazolium chloride ([COOH-EtMIm][Cl])-catalyzed dehydrogenation coupling reaction of subsituted thiophenols and isochroman in the presence of O_2.The influencing factors were screened by single factor experiments,and the optimal reaction conditions were obtained as follows:p-toluenethiol (62 mg,0.5 mmol),isochroman(134 mg,1.0 mmol),[COOH-EtMIm][Cl](95 mg,0.5 mmol),O_(2) pressure 0.10 MPa,reaction temperature120℃,and reaction time 12 h.Under the optimum reaction conditions,the catalyst could be recycled for 4times,while the gram-scale synthesis of 1-thiophenol isochroman was accomplished and 12 kinds of1-substituted thiophenol isochromans with yields ranging from 52%to 96%were obtained.In addition,activation of thiophenol and isochroman by anion and cation ions of[COOH-EtMIm][Cl],respectively,followed by O_(2) oxidation and final dehydrogenation to form 1-thiophenol isochroman,was proposed as the reaction mechanism.