Dual activation in oxidative coupling of 2-naphthols catalyzed by chiral dinuclear vanadium complexes
作者:Shinobu Takizawa、Tomomi Katayama、Hidenori Somei、Yasuaki Asano、Tomokazu Yoshida、Chiaki Kameyama、Doss Rajesh、Kiyotaka Onitsuka、Takeyuki Suzuki、Masafumi Mikami、Hiroshi Yamataka、Doss Jayaprakash、Hiroaki Sasai
DOI:10.1016/j.tet.2008.01.110
日期:2008.4
An efficient enantioselective oxidative coupling of 2-naphthol derivatives based on a concept of dual activation catalysis is realized. A chiral dinuclear vanadium(IV) complex (Ra,S,S)-1e possessing (S)-tert-leucine moieties at the 3,3′-positions of the (R)-binaphthyl skeleton was developed, which was found to promote the oxidative coupling of 2-naphthol to afford (S)-BINOL with 91% ee. To verify the
基于双重活化催化的概念,实现了2-萘酚衍生物的有效对映选择性氧化偶联。的手性双核钒(IV)配合物([R一个,小号,小号) - 1E具有(小号) -叔-亮氨酸部分在(的3,3'-位置[R )联萘骨架的开发,发现其促进2-萘酚的氧化偶联,得到具有91%ee的(S)-BINOL。为了验证双重激活机制,单核钒(IV)配合物(S)-8也准备好了。动力学分析表明,由(促进2-萘酚的氧化偶联的反应速率ř一个,小号,小号) - 1E比(快48.3倍小号) - 8。手性络合物中的两种钒金属以分子内偶联反应的方式同时活化了2-萘酚的两个分子,从而实现了高反应速率和高对映体控制。还描述了钒(IV)或钒(V)配合物促进的氧化偶联反应的反应机理。