Chain propagation determines the chemo- and regioselectivity of alkyl radical additions to C–O vs. C–C double bonds. Issue 3 (2nd December 2019)

• Record Type: Journal Article
• Authors: Paulisch, Tiffany O.; Strieth-Kalthoff, Felix; Henkel, Christian; Pitzer, Lena; Guldi, Dirk M.; Glorius, Frank
• Is Part Of: Chemical science. Volume 11:Issue 3(2020)
• Page Start: 731
• Page End: 736
• Publication Date: 2019-12-02
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c9sc04846d
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Reversible radical addition followed by an irreversible electron transfer leads to regio- and chemoselectivity control of radical additions to π-systems. Abstract : Investigations into the selectivity of intermolecular alkyl radical additions to C–O- vs. C–C-double bonds in α, β-unsaturated carbonyl compounds are described. Therefore, a photoredox-initiated radical chain reaction is explored, where the activation of the carbonyl-group through an in situ generated Lewis acid – originating from the substrate – enables the formation of either C–O or the C–C-addition products. α, β-Unsaturated aldehydes form selectively 1, 2-, while esters and ketones form the corresponding 1, 4-addition products exclusively. Computational studies lead to reason that this chemo- and regioselectivity is determined by the consecutive step, i.e. an electron transfer, after reversible radical addition, which eventually propagates the radical chain.