title: Repairing the thiol-ene coupling reaction.
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.
authors.affiliation: Universität Bern, Departement für Chemie und Biochemie, Freiestrasse 3, 3012 Bern (Switzerland).
authors.forename: Guillaume
authors.initials: G
authors.lastname: Povie
authors.forename: Anh-Tuan
authors.initials: AT
authors.lastname: Tran
authors.forename: David
authors.initials: D
authors.lastname: Bonnaffé
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Habegger
authors.forename: Zhaoyu
authors.initials: Z
authors.lastname: Hu
authors.forename: Christine
authors.initials: C
authors.lastname: Le Narvor
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
mesh_terms: D000498:Allyl Compounds / Q000737:chemistry*; D001880:Boranes; D020650:Combinatorial Chemistry Techniques; D006027:Glycosides; D015394:Molecular Structure; D013237:Stereoisomerism; D013863:Thioglucosides / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000498:Allyl Compounds; D001880:Boranes; D006027:Glycosides; D013863:Thioglucosides
keywords: allylic compounds; boranes; glycosides; radical reactions; synthetic methods