Metal-free glycosylation with glycosyl fluorides in liquid SO₂

• Krista Gulbe,
• Jevgeņija Lugiņina,
• Edijs Jansons,
• Artis Kinens and
• Māris Turks

Beilstein J. Org. Chem. 2021, 17, 964–976, doi:10.3762/bjoc.17.78

• reaction was observed and mannosyl fluoride α-1a was fully recovered. Recently, Pedersen et al. have studied the vessel effect on the C–F bond activation of glucosyl fluorides [63]. They have proposed an autocatalytic glycosylation by SiF4 generated in situ form initially released HF that reacts with

Activation of pentafluoropropane isomers at a nanoscopic aluminum chlorofluoride: hydrodefluorination versus dehydrofluorination

• Maëva-Charlotte Kervarec,
• Thomas Braun,
• Mike Ahrens and
• Erhard Kemnitz

Beilstein J. Org. Chem. 2020, 16, 2623–2635, doi:10.3762/bjoc.16.213

• such as hydrodefluorinations and dehydrofluorinations were observed, followed by hydroarylation and Friedel–Crafts-type reactions under mild conditions. Keywords: aluminum fluoride; C–F bond activation; dehydrofluorination; hydrodefluorination; hydrofluorocarbons; Introduction Hydrofluorocarbons

• in part needed due to the high dissociation energy of C–F bonds, and in general, C–F activation steps are considered to be challenging [20][21][22][23][24][25][26][27]. Solid Lewis acids with a high fluoride ion affinity as catalysts are useful tools for C–F bond activation reactions since the Lewis

• , Scheme 5). It is likely that silylium species are involved in the C–F activation steps at the ACF surface since HSiEt3 is needed to initiate any reactivity. On the one hand, an initial C–F bond activation at 10c by some silylium ion species will produce FSiEt3 and the corresponding carbenium species

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Stereochemical outcomes of C–F activation reactions of benzyl fluoride

• Neil S. Keddie,
• Pier Alexandre Champagne,
• Justine Desroches,
• Jean-François Paquin and
• David O'Hagan

Beilstein J. Org. Chem. 2018, 14, 106–113, doi:10.3762/bjoc.14.6

• years, there has been an increasing interest in C–F bond activation [2], with a view to using organic bound fluoride as a leaving group in substitution reactions that typically require more activated leaving groups. Such an approach could circumvent the requirement for protecting groups in multistep

• synthesis by capitalizing on the low reactivity of the C–F bond. Paquin et al. have published extensively on non-metal based methods for benzylic C–F bond activation [3][4][5][6][7]. The reactivity relies on protic activation driven by the capacity of organic fluoride to form hydrogen bonds [8][9

Triol-promoted activation of C–F bonds: Amination of benzylic fluorides under highly concentrated conditions mediated by 1,1,1-tris(hydroxymethyl)propane

• Pier Alexandre Champagne,
• Alexandre Saint-Martin,
• Mélina Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2013, 9, 2451–2456, doi:10.3762/bjoc.9.283

• under highly concentrated conditions, where solvents cannot interfere with the interaction between the organofluorine compound and the triol. Various benzylic fluorides react with secondary amines or anilines to form benzylic amines in good yields. Keywords: C–F bond activation; highly concentrated

• ). Conclusion In summary, we have described that according to our previous proposed mechanism for the hydrogen bond-promoted C–F bond activation [17], simultaneous coordination of the three lone pairs of fluorine by a triol (e.g. 2) permits the nucleophilic substitution of benzylic fluorides by amines under