Repairing the Thiol‐Ene Coupling Reaction

作者：Guillaume Povie, Anh‐Tuan Tran, David Bonnaffé, Jacqueline Habegger, Zhaoyu Hu, Christine Le Narvor, Philippe Renaud · 发表于：Angewandte Chemie International Edition · 年份：2014 · DOI：10.1002/anie.201309984 · 被引用次数：63 · 研究领域：Sulfur-Based Synthesis Techniques、Radical Photochemical Reactions、Carbohydrate Chemistry and Synthesis

Thiol-ene coupling (TEC) reactions emerged as one of the most useful processes for coupling different molecular units under reaction mild conditions. However, TEC reactions involving weak CH bonds (allylic and benzylic fragments) are difficult to run and often low yielding. Mechanistic studies demonstrate that hydrogen-atom transfer processes at allylic and benzylic positions are responsible for the lack of efficiency of the radical-chain process. These competing reactions cannot be prevented, but reported herein is a method to repair the chain process by running the reaction in the presence of triethylborane and catechol. Under these reaction conditions, a unique repair mechanism leads to an efficient chain reaction, which is demonstrated with a broad range of anomeric O-allyl sugar derivatives including mono-, di-, and tetrasaccharides bearing various functionalities and protecting groups.