36852-02-5Relevant academic research and scientific papers
Cobalt-xantphos-catalyzed, LiCl-mediated preparation of arylzinc reagents from aryl iodides, bromides, and chlorides
Jin, Meng-Yi,Yoshikai, Naohiko
experimental part, p. 1972 - 1978 (2011/05/19)
A cobalt-Xantphos-catalyzed, LiCl-mediated system has been developed for the direct and expedient preparation of arylzinc reagents in THF from the corresponding aryl iodides, bromides, and chlorides. Owing to the use of THF as a versatile solvent, the thus-formed arylzinc reagents displayed a high degree of compatibility with a variety of conventional as well as newly emerging metal-catalyzed cross-coupling reactions.
Homocoupling of arylboronic acids catalyzed by CuCl in air at room temperature
Cheng, Guanjun,Luo, Meiming
experimental part, p. 2519 - 2523 (2011/06/10)
Homocoupling of arylboronic acids has been successfully carried out by using the inexpensive simple copper salt CuCl as the catalyst in methanol to obtain symmetric biaryls in good to excellent yields. The reaction proceeds with a CuCl loading of 2 mol-% under extremely mild conditions: in air, at room temperature, without the need of any additives such as base, oxidant, or ligand. A simple and efficient CuCl-catalyzed homocoupling of arylboronic acids for the synthesis of symmetrical biaryls is described. The homocoupling reaction takes place with a catalyst loading of at 2 mol-% in economical and easily handled methanol and under extremely mild conditions: in air, at room temperature, without any additives such as base, oxidant, or ligand. Copyright
Heck reaction catalyzed by Pd/C, in a triphasic - Organic/Aliquat 336/aqueous - solvent system
Perosa, Alvise,Tundo, Pietro,Selva, Maurizio,Zinovyev, Sergei,Testa, Alberto
, p. 2249 - 2252 (2007/10/03)
The rate of the Pd/C catalyzed Heck coupling of Ar-I with CH 2=CH-R is accelerated tenfold by the presence of Aliquat 336 (A336), a well known phase transfer catalyst, and an ionic liquid. Both when conducted in A336 as solvent, and in an isooctane/A336/aqueous triphasic mixture, the Heck reaction of aryl iodides with electron deficient olefins, catalyzed by Pd/C, proceeds with high yields and selectivity. When KOH is used instead of Et3N, selective formation of the biphenyl rather than the Heck product, is observed. Aryl bromides react more sluggishly, and only the more activated ones undergo the Heck reaction. In the absence of the olefin, aryl halides possessing an electron withdrawing group are reduced to the corresponding Ar-H.
New chemical synthesis of functionalized arylzinc compounds from aromatic or thienyl bromides under mild conditions using a simple cobalt catalyst and zinc dust
Fillon, Hyacinthe,Gosmini, Corinne,Perichon, Jacques
, p. 3867 - 3870 (2007/10/03)
A new chemical method for the preparation of arylzinc intermediates is described in acetonitrile, on the basis of the activation of aryl bromides by low-valent cobalt species arising from the reduction of cobalt halide by zinc dust. This procedure allows for the synthesis of a variety of functionalized aryl- and thienylzinc species in good to excellent yields. The versatility and the simplicity of that original method represent an alternative to most known procedures.
An improved preparation of arylboronates: Application in one-pot Suzuki biaryl synthesis
Zhu, Lei,Duquette, Jason,Zhang, Mingbao
, p. 3729 - 3732 (2007/10/03)
We have developed a modification of the Miyaura arylboronate synthesis1a by substituting a ligandless palladium catalyst for PdCl2(dppf). Palladium acetate, free of ligand, was found highly effective for such coupling reactions. This modified procedure is advantageous over the original Miyaura synthesis in ease of workup, catalyst removal, and low catalyst cost. Furthermore, the boronates formed in this manner can be used directly for Suzuki coupling reactions in a one-pot fashion. The biaryl products have improved impurity profiles and reduced heavy metal contamination.
Vapour-phase Chemistry of Arenes. Part 13. Reactivity and Selectivity in the Gas-phase Reactions of Hydroxyl Radicals with Monosubstituted Benzenes at 563 K
Mulder, Peter,Louw, Robert
, p. 1167 - 1174 (2007/10/02)
The reactions of hydroxyl radicals with benzene derivates C6H5Z (Z = H, Me, F, Cl, Br, I, CF3, or CN) have been studied in a flow reactor at 563 K in nitrogen, using the thermolysis of ButOOH as a source of .OH.Under these conditions there are two product-forming pathways.The major one involves hydrogen abstraction to give aryl radicals ZC6H4. (II) as the first step; depending on Z, its displacement to form phenol may also occur.Relative rates for hydrogen abstraction were determined in competition experiments using side-chain hydrogen abstraction from added toluene as a reference.This resulted in the order (for Z =): 1,8(Me), 1.0(H), 0.47(F), 0.29(Cl), 0.34(CF3), 0.20(CN), consonant with the electrophilic nature of .OH.The site selectivity of hydrogen abstractions was determined by scavenging part of the aryl radicals (II) with iodine.A Hammett plot, using ? constants for meta and para positions, led to ρ -1.0.The features of hydrogen abstraction by .OH are discussed and compared with those for the analogous reaction of Cl.The formation of phenol was found to decrease in importance in the order F, Cl, Br, and I.This result is rationalized on a thermochemical kinetic basis.
