Simple and expedient metal-free CH-functionalization of fluoro-arenes by the BHAS method – Scope and limitations

Formaldehyde‐Extruding Homolytic Aromatic Substitution via C→O Transposition: Selective ‘Traceless‐Linker’ access to Congested Biaryl Bonds

“…During optimisation of the “acetal method” part of the investigations of the BHAS reaction,,—two of us reported the isolation of 2‐phenylphenol ( 7 ) as a by‐product . The procedure employed a molecular tether placed in sequence to form heterodimers with 2‐bromophenol resulting in a methylene bridge and the namesake acetal.…”

Dual C–F, C–H Functionalization via Photocatalysis: Access to Multifluorinated Biaryls

“…12–19 Alternatively, methods characterized by the use of less functionalized molecules (i.e. H 20 on one or both partners) have also been developed ( Approach B ). 21–23 Typically, activated multifluorinated arenes are derived from the C–F bond in 1–3 steps, i.e.…”

Star-shaped triarylamines – One-step metal-free synthesis and optoelectronic properties

“…Promising earlier reports on the synthesis of fluorinated biaryls via the BHAS methodology, prompted us to apply the established reaction conditions to the synthesis of TAAs. 54 We performed the biaryl coupling of tris(4-iodophenyl)amine 1 with benzene 2a at 100 °C (Table 1, Entry 1) using 1,10-phenanthroline 4 (0.90 equiv.) as activating organic additive in combination with t-BuOK (9.0 equiv.)…”

“…[29][30][31][32] Most reports focused on bases such as tert-butoxides (t-BuOM, M = K or Na), with t-BuOK being the most efficient, 28,[38][39][40][41][42][43][44][45][46][47] but also potassium ethoxide (EtOK) 48 and potassium tert-amylate (t-AmOK) 49 can mediate the reaction process. A wide variety of activating organic additives is used alongside the base, ranging from diamine ligands (N,N´dimethylethylenediamine, 43,44,[49][50][51][52][53] 1,10-phenanthroline and its derivatives, 43,[47][48][49][53][54][55][56][57][58][59][60][61][62][63] hydrazine and its derivatives 41,64 ) over alcohols 49,51,53,65 and 1,2-diols 49,51 to N-heterocycles (pyridines,…”

“…68 Furthermore, BHAS has served as a multi-bond forming reaction, realizing the double biaryl coupling of dihalobenzenes with benzene and achieving extended π-electron systems. [39][40][41][42]48,49,52,54,56,[69][70][71] A significant contribution to the development of the multi-bond forming BHAS methodology comes from the work of Masters who performed both intra-and intermolecular BHAS on scaffolds bearing two halogen groups on different arenes in the presence of coupling partners not limited to benzene. 56 Inspired by those results, we targeted a novel one-step transition-metal-free multi-bond forming synthesis of substituted star-shaped triarylamines.…”