Sirin-Sariaslan Ayla, Naumann Stefan
University of Stuttgart, Institute of Polymer Chemistry 70569 Stuttgart Germany
Chem Sci. 2022 Aug 31;13(36):10939-10943. doi: 10.1039/d2sc03977j. eCollection 2022 Sep 21.
It is demonstrated that stereoselective polymerization of epoxides, long a domain of metal-based compounds, can also be achieved the application of organocatalysts. A simple two-step synthesis starting from widely available 1,1'-bi-2-naphthol (BINOL) backbones yields diboranes which, in tandem with organobases, deliver isotactic-enriched () polyethers from the homopolymerization of racemic propylene oxide (PO) and other epoxides. Thereby, isotactic diad contents of up to 88% can be achieved, resulting in well-defined (1.1 < < 1.3) polyethers with high molar masses ( > 100 000 g mol). Notably, it is also possible to grow -enriched sequences of PPO on aliphatic polyester-type initiators, thus enabling the incorporation of stereocontrolled polyether blocks in more complex polymer architectures. It is expected that this ability will greatly benefit the preparation of polyether-containing additives. The BINOL-type diboranes can be readily modified, suggesting further potential as a platform from which optimized catalysts can be developed.
结果表明，长期以来一直由金属基化合物主导的环氧化物立体选择性聚合，也可以通过有机催化剂的应用来实现。从广泛可得的1,1'-联二萘酚（BINOL）骨架出发，经过简单的两步合成可得到二硼烷，二硼烷与有机碱一起，能从外消旋环氧丙烷（PO）和其他环氧化物的均聚反应中得到富含全同立构的（）聚醚。由此，全同立构二单元含量可达88%，从而得到具有明确特性（1.1 << 1.3）且摩尔质量高（> 100 000 g mol）的聚醚。值得注意的是，也有可能在脂肪族聚酯型引发剂上生长富含全同立构的聚环氧丙烷序列，从而能够在更复杂的聚合物结构中引入立体控制的聚醚嵌段。预计这种能力将极大地有利于含聚醚添加剂的制备。BINOL型二硼烷易于改性，这表明其作为一个可开发优化催化剂的平台具有进一步潜力。
