高等学校化学学报 ›› 1998, Vol. 19 ›› Issue (S1): 93.
• Organic Synthesis Chemistry • 上一篇 下一篇
Tong-Shuang Li, Hui-Yun Duan, Bao-Zhi Li, Brij B. Tewari, Sheng-Hui Li
Tong-Shuang Li, Hui-Yun Duan, Bao-Zhi Li, Brij B. Tewari, Sheng-Hui Li
摘要: l,l'-Bi-2-naphthol derivatives have wide applications as chiral inducing agents for asymmetric synthesis.1 There are many good methods for resolution of racemic binaphthols to give enantiomeric binaphthols.2 Therefore, it is essential to established simple, convenient, economically and environmental-friendly methods for preparation of racemic l,l'-binaphthol derivatives. A number of methods have been developed for the oxidative coupling of 2-naphthols usually by using Fe3+, Cu2+ or Mn3+ as oxidants. The reaction were carried out in organic solvent,3a in solid state3b and in aqueous Fe3+ solution.3c However, all those cases by employing excess, usually 2 equivalents of oxidant. The excess Fe3+, Cu2+ and the resulted Fe2+, Cu+ and HCl were not acceptable from a view point of environmental protection. Recently, Sakamoto et at4 and Kantam et at5 independently reported two catalytic oxidative coupling procedure for preparation of l,l'-binaphthols using aerial oxygen as oxidant and Cu2+-exchanged montmorillonite as catalysts. However, both procedures were by using some toxic chlorobenzene as solvent and long reaction time (>2 h) and high temperature(>140℃) were needed. Consquently, there is still a great demand for catalytic oxidative coupling 2-naphthols to generate binaphthols under mild conditions, environmentally friendly procedure and rapid process. Herein we report novel oxidative coupling of to 1,1-bi-2-naphthols (2a, 2b) catalysed by a number of supported reagents using aerial oxygen as oxidant. The results are listed in Table 1.
TrendMD: