Sirin-Sariaslan A, Naumann S. Chiral Diboranes as Catalysts for the Stereoselective Organopolymerization of Epoxides.
Chem Sci 2022;
13:10939-10943. [PMID:
36320696 PMCID:
PMC9491197 DOI:
10.1039/d2sc03977j]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 08/30/2022] [Indexed: 11/22/2022] Open
Abstract
It is demonstrated that stereoselective polymerization of epoxides, long a domain of metal-based compounds, can also be achieved via 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 (it) 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 < ĐM < 1.3) polyethers with high molar masses (Mn > 100 000 g mol−1). Notably, it is also possible to grow it-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.
Chiral diborane catalysts deliver well-defined isotactic-enriched polyether, whereby also polyester-type macroinitiators can be employed.![]()
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