Azaphosphatranes as Hydrogen-Bonding Organocatalysts for the Activation of Carbonyl Groups: Investigation of Lactide Ring-Opening Polymerization

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• 作者：Dawei Zhang ; Damien Jardel ; Fré ; dé ; ric Peruch ; Nathalie Calin ; Vé ; ronique Dufaud ; Jean-Pierre Dutasta ; Alexandre Martinez and Brigitte Bibal
• 关键词：Phosphorus ; Hydrogen bonds ; Organocatalysis ; Ring-opening polymerization ; Lactide
• 刊名：European Journal of Organic Chemistry
• 出版年：2016
• 出版时间：March 2016
• 年：2016
• 卷：2016
• 期：8
• 页码：1619-1624
• 全文大小：851K
• ISSN：1099-0690

文摘

The hydrogen-bonding activation of C=O bonds by azaphosphatranes was explored in a model reaction, i.e., the ring-opening polymerization of lactide. The polymerization process was controlled, and allowed the preparation of polylactides with narrow dispersity under mild conditions (20 °C, 24 h, 10 mol-% catalyst loading). Interestingly, the steric hindrance of azaphosphatranes, as globular rigid structures, prevents any undesired interaction with the tertiary amine cocatalysts, as shown by X-ray analysis and semi-empirical calculations. In contrast to their organocatalytic activity in the CO₂/epoxide reaction, all of the phosphonium derivatives tested were found to be efficient catalysts in this ROP benchmark reaction.