Ionisation of the ZincIodine Bond of Alkylzinc Iodides in Dimethylformamide from Theory and Experiment

Abstract

Patterns of communication: Reinitzer's discovery of liquid crystals in 1888 was followed by 30 years of scholarly dispute. One hundred years later, Pierre‐Gilles de Gennes was awarded the Nobel Prize in Physics for his contribution to this scientific revolution. The commercial success of liquid crystals was achieved in display applications. Today more than 4 billion people use them in mobile communication devices. Painting: Detail from Raphael's School of Athens fresco.

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

“…62 Jackson and co-workers have used a higher level of theory [B3LYP/SDD(6-311G**)] to distinguish between pentacoordinate and tetracoordinate geometries for alkylzinc iodides in DMF. 63 Monomer complex 20b was therefore examined at this level of theory and the integrity of the pentacoordinate geometry was maintained. Non-coordinated tetrahedral geometry 25 ( Fig.…”

Carbon–Carbon Bond Forming Reactions Mediated by Organozinc Reagents

“…Palladium-phosphine complexes are the most commonly used catalysts. Palladium-PPh 3 complexes, either isolated such as Pd(PPh 3 ) 4 or formed in situ from typical palladium precatalysts such as Pd 2 (dba) 3 or Pd(OAc) 2 and PPh 3 , afford satisfactory results in many cases. For the more demanding situations, other conventional phosphine ligands such as tfp (tris(2-furyl)phosphine), PtBu 3 , dppf, or DPEPhos (174) can help to achieve superior results.…”

“…Cross-coupling with aryl chlorides can be achieved within minutes in high yields with very low catalyst loadings using a combination of Pd 2 (dba) 3 and PtBu 3 [139]. The same technique can be utilized in the Negishi cross-coupling catalyzed by palladium in the presence of the ligand 160 of the JosiPhos family, providing the enantioselective formation of chiral binaphthyls such as 159 (Scheme 4.36) [140].…”

“…In another notable application of the palladium-catalyzed cross-coupling of nitrogen-containing organozincs, reagents derived from amino acids react with aryl halides in DMF using P(o-Tol) 3 , tris(ortho-tolyl)phosphine as ligand (Scheme 4.81) [5]. The approach is equally well suited for the preparation of arylated α-amino acids [255,256] such as 358 or β-amino acids [257].…”

“…It has been found that bromide salts tend to be superior to chloride or iodide salts and the influence of the cation is minor [270]. The higher order zincate Zn(nBu)Br 3 2− has been suggested to be the active transmetallation agent. Its formation depends not only on the stoichiometry of the different salts but also on the polarity of the solvent.…”