Repairing the Thiol‐Ene Coupling Reaction |
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Authors: | Dr. Guillaume Povie Dr. Anh‐Tuan Tran Prof. David Bonnaffé Jacqueline Habegger Zhaoyu Hu Dr. Christine Le Narvor Prof. Philippe Renaud |
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Affiliation: | 1. Universit?t Bern, Departement für Chemie und Biochemie, Freiestrasse 3, 3012 Bern (Switzerland);2. ICMMO/MS&MT, UMR 8182 (CNRS‐UPS), LabEx LERMIT, Université Paris‐Sud, 91405 Orsay Cedex (France) |
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Abstract: | 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. |
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Keywords: | allylic compounds boranes glycosides radical reactions synthetic methods |
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