5617-39-0Relevant academic research and scientific papers
Replacing conventional carbon nucleophiles with electrophiles: Nickel-catalyzed reductive alkylation of aryl bromides and chlorides
Everson, Daniel A.,Jones, Brittany A.,Weix, Daniel J.
supporting information; experimental part, p. 6146 - 6159 (2012/05/07)
A general method is presented for the synthesis of alkylated arenes by the chemoselective combination of two electrophilic carbons. Under the optimized conditions, a variety of aryl and vinyl bromides are reductively coupled with alkyl bromides in high yields. Under similar conditions, activated aryl chlorides can also be coupled with bromoalkanes. The protocols are highly functional-group tolerant (-OH, -NHTs, -OAc, -OTs, -OTf, -COMe, -NHBoc, -NHCbz, -CN, -SO2Me), and the reactions are assembled on the benchtop with no special precautions to exclude air or moisture. The reaction displays different chemoselectivity than conventional cross-coupling reactions, such as the Suzuki-Miyaura, Stille, and Hiyama-Denmark reactions. Substrates bearing both an electrophilic and nucleophilic carbon result in selective coupling at the electrophilic carbon (R-X) and no reaction at the nucleophilic carbon (R-[M]) for organoboron (-Bpin), organotin (-SnMe3), and organosilicon (-SiMe2OH) containing organic halides (X-R-[M]). A Hammett study showed a linear correlation of σ and σ(-) parameters with the relative rate of reaction of substituted aryl bromides with bromoalkanes. The small ρ values for these correlations (1.2-1.7) indicate that oxidative addition of the bromoarene is not the turnover-frequency determining step. The rate of reaction has a positive dependence on the concentration of alkyl bromide and catalyst, no dependence upon the amount of zinc (reducing agent), and an inverse dependence upon aryl halide concentration. These results and studies with an organic reductant (TDAE) argue against the intermediacy of organozinc reagents.
Copper-catalyzed cross-coupling reaction of organoboron compounds with primary alkyl halides and pseudohalides
Yang, Chu-Ting,Zhang, Zhen-Qi,Liu, Yu-Chen,Liu, Lei
, p. 3904 - 3907 (2011/05/15)
Non-activated alkyl electrophiles, including alkyl iodides, bromides, tosylates, mesylates, and even chlorides, underwent copper-catalyzed cross-coupling with aryl boron compounds and alkyl 9-BBN reagents (see scheme; 9-BBN=9-borabicyclo[3.3.1]nonane). The reactions proceed with practically useful reactivities and thus complement palladium- and nickel-catalyzed Suzuki-Miyaura coupling reactions of alkyl halides.
Nickel-catalyzed reductive cross-coupling of aryl halides with alkyl halides
Everson, Daniel A.,Shrestha, Ruja,Weix, Daniel J.
supporting information; experimental part, p. 920 - 921 (2010/03/31)
(Chemical Equation Presented) The direct reductive cross-coupling of alkyl halides with aryl halides is described. The transformation is efficient (equimolar amounts of the starting materials are used), generally high-yielding (all but one between 55 and 88% yield), highly functional-group-tolerant [OH, NHBoc, NHCbz, Bpin, C(O)Me, CO2Et, and CN are all tolerated], and easy to perform (uses only benchtop-stable reagents, tolerates small amounts of water and oxygen, changes color when complete, and uses filtration workup). The reaction appears to avoid the formation of intermediate organomanganese species, and a synergistic effect was found when a mixture of two ligands was employed.
Pd-catalyzed cleavage of benzylic nitro bonds: New opportunities for asymmetric synthesis
Fessard, Thomas C.,Motoyoshi, Hajime,Carreira, Erick M.
, p. 2078 - 2081 (2008/02/13)
Without a trace: Benzylic nitroalkanes are reduced to the corresponding parent alkanes in good yields by using a simple procedure involving heterolytic C-N bond cleavage (see scheme). Traceless removal of the nitro group leaves behind a stereogenic center that may otherwise be difficult to install. This reaction significantly expands the scope of building blocks that can be accessed. (Chemical Equation Presented)
Process for preparing pentacene derivatives
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, (2008/06/13)
A process for preparing substituted pentacene compounds comprises the step of cyclizing substituted bis(benzyl)phthalic acids using an acid composition comprising trifluoromethanesulfonic acid, the substituted bis(benzyl)phthalic acids being represented by the following general formulas: wherein each R (that is, each of the groups R1 through R8) is independently an electron-donating group, a halogen atom, a hydrogen atom, or a combination thereof.
Substituted pentacene semiconductors
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Page/Page column 25, (2010/02/11)
Substituted pentacene compounds comprise at least one substituent selected from the group consisting of electron-donating substituents, halogen substituents, and combinations thereof; the substituent(s) each being bonded to a carbon atom of a terminal ring of pentacene, and being the only substituent(s); with the proviso that when the compound has only two substituents, both of which are methyl or alkoxy, and one substituent is bonded to the number 2 carbon atom, the other substituent, if methyl, is bonded to the number 1, 3, 4, 8, or 11 carbon atom and, if alkoxy, is bonded to the number 1, 3, 4, 8, 9, or 11 carbon atom; and with the further proviso that when the compound has only four substituents, all of which are alkoxy, the substituents are bonded to the numbers 2, 3, 9, and 10 carbon atoms.
