Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States.
J Am Chem Soc. 2010 Nov 24;132(46):16520-5. doi: 10.1021/ja1058422. Epub 2010 Nov 2.
A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (k(fast)/k(slow)) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T(m) values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides.
一种高活性的手性纯双金属钴配合物被探索用于各种单取代环氧化物的对映选择性聚合。通过优化聚合条件，以获得高反应速率和对映选择性，大多数环氧化物的 s 因子（k（快）/k（慢））超过 50，有些甚至超过 300，远远超过了手性纯环氧化物和等规聚醚在制备方面的应用阈值。所得聚合物的 mm 三单元组的数值通常大于 95%，有些甚至超过 98%。此外，使用外消旋催化剂可以定量制备等规聚醚。本文还介绍了这些等规聚醚的热性能，许多聚合物表现出高 T(m)值。这是首例通过外消旋环氧化物的对映选择性聚合快速合成广泛的高等规聚醚的报道。
