Negishi coupling of 2-pyridylzinc bromide—paradigm shift in cross-coupling chemistry?

High Stokes Shift Anilido‐Pyridine Boron Difluoride Dyes

“…The more rigid bidentate nitrogen donor in compounds 2 a – b was prepared through palladium‐catalyzed Hartwig–Buchwald amination13 of 10‐bromobenzo[ h ]quinoline using aniline ( 2 a , 76 %) or 2,6‐diisopropylaniline ( 2 b , 46 %). Finally, the ligands in compounds 3 a – b , based on the 9 H ‐carbazole unit were prepared using a Negishi coupling protocol14 from the potassium salt of the corresponding carbazole bromide and a 2‐pyridylzinc reagent15 in 67–85 % yield.…”

One-pot near-ambient temperature syntheses of aryl(difluoroenol) derivatives from trifluoroethanol

“…Organozinc reagents are sometimes avoided because of their sensitivity to moisture and are usually formed in situ for immediate consumption; however, Leitner and co-workers discovered that a solution of 2-pyridylzinc bromide could be stored for more than 12 months at room temperature without any significant decomposition. 52 A solution of reagent 9b was stored in the refrigerator for 7 days prior to Negishi coupling with 16a using the standard conditions. A 65% yield of styrene 12ba was obtained from a coupling carried out at the end of that period, revealing that 9b is relatively stable in solution, and certainly amenable to batch preparation.…”

The 2‐Pyridyl Problem: Challenging Nucleophiles in Cross‐Coupling Arylations

“…Organozinc reagents can be obtained via direct, or transition‐metal‐catalysed, oxidative addition of zinc into carbon−halide bonds, transmetalation of metalated substrates with a zinc source such as ZnCl 2 or ZnBr 2 , or by direct zincation of C−H bonds [22] . These methods can be applied on multi‐kilogram scale to 2‐pyridyl substrates, which do not suffer from any particular instability compared to their carbocyclic analogues [23] . Negishi cross‐coupling protocols developed for carbocyclic substrates [24] were adapted to 2‐pyridyl derivatives without major changes [25] .…”