2132-85-6Relevant academic research and scientific papers
Synthesis and Reactivity of Paramagnetic Nickel Polypyridyl Complexes Relevant to C(sp2)–C(sp3)Coupling Reactions
Mohadjer Beromi, Megan,Brudvig, Gary W.,Hazari, Nilay,Lant, Hannah M. C.,Mercado, Brandon Q.
supporting information, p. 6094 - 6098 (2019/04/03)
A number of new transition metal catalyzed methods for the formation of C(sp2)–C(sp3) bonds have recently been described. These reactions often utilize bidentate polypyridyl-ligated Ni catalysts, and paramagnetic NiI halide or aryl species are proposed in the catalytic cycles. However, there is little knowledge about complexes of this type. Here, we report the synthesis of paramagnetic bidentate polypyridyl-ligated Ni halide and aryl complexes through elementary reactions proposed in catalytic cycles for C(sp2)–C(sp3) bond formation. We investigate the ability of these complexes to undergo organometallic reactions that are relevant to C(sp2)–C(sp3) coupling through stoichiometric studies and also explore their catalytic activity.
Redox-Active Esters in Fe-Catalyzed C-C Coupling
Toriyama, Fumihiko,Cornella, Josep,Wimmer, Laurin,Chen, Tie-Gen,Dixon, Darryl D.,Creech, Gardner,Baran, Phil S.
, p. 11132 - 11135 (2016/10/12)
Cross-couplings of alkyl halides and organometallic species based on single electron transfer using Ni and Fe catalyst systems have been studied extensively, and separately, for decades. Here we demonstrate the first couplings of redox-active esters (both isolated and derived in situ from carboxylic acids) with organozinc and organomagnesium species using an Fe-based catalyst system originally developed for alkyl halides. This work is placed in context by showing a direct comparison with a Ni catalyst for >40 examples spanning a range of primary, secondary, and tertiary substrates. This new C-C coupling is scalable and sustainable, and it exhibits a number of clear advantages in several cases over its Ni-based counterpart.
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.
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.
Synergistic effects of alkali metals in the alkylation of naphthalene and toluene with ethene in the ArH-alkali metal systems in THF (ArH - naphthalene, phenanthrene)
Rummel,Yunusov,Kalyuzhnaya,Shur
experimental part, p. 1467 - 1472 (2009/09/06)
The use of mixtures of metallic lithium and sodium in the naphthalene-alkali metal systems in THF leads to a synergistic acceleration of the naphthalene alkylation with ethene at room temperature and atmospheric pressure. The greatest synergistic effect is observed at a Li:Na molar ratio of 2:1. Under these conditions, the overall conversion of naphthalene into alkylation products (linear 1-alkylnaphthalenes and their dihydro derivatives) attains 88% after 24 h (a (Li + Na):C10H8 ratio is 2:1). The use of mixtures of metallic lithium and potassium in such systems results, however, in a synergistic retardation of the alkylation process. The strongest retarding effect is observed at a Li:K molar ratio of 1:1. The efficiency of the toluene alkylation with ethene in the naphthalene-alkali metal systems in THF is also increased on the replacement of lithium or sodium by their mixtures. The best results are obtained at a Li:Na molar ratio of 1:3. With this Li:Na ratio, toluene is almost quantitatively converted into linear and α-branched higher monoalkylbenzenes (24 h, (Li + Na):C10H8 = 2:1). The rate of the naphthalene alkylation with ethene in the presence of toluene is enhanced as well on an introduction of mixtures of lithium and sodium into the system. However the maximum of the activity is shifted here towards higher lithium content (Li:Na = 1:1). A similar synergistic effect of lithium and sodium was found on studying the toluene alkylation with ethene in the phenanthrene-Li-Na systems in THF (a (Li + Na):phenanthrene ratio is 3:1). An addition of potassium to sodium also considerably increases the efficiency of the toluene and naphthalene alkylation with ethene in the naphthalene-based systems. The possible mechanism of the alkali metal synergism in the above-mentioned alkylation reactions is discussed.
Activation of C-H bonds of hydrocarbons by the ArH-alkali metal systems in THF (ArH - naphthalene, biphenyl, anthracene, phenanthrene, trans-stilbene, pyrene). Alkylation of naphthalene and toluene with ethene
Rummel,Ilatovskaya,Yunusov,Kalyuzhnaya,Shur
scheme or table, p. 1459 - 1466 (2009/09/06)
Systems based on naphthalene and alkali metals (Li, Na, K) in THF are able to induce the alkylation of naphthalene with ethene at room temperature and atmospheric pressure. The highest activity in this reaction is exhibited by the naphthalene-potassium system which converts naphthalene into 1-ethylnaphthalene (1) and small amounts of two isomeric dihydro derivatives of 1 in a yield of 85% (24 h, K:C10H8 = 2:1). The same alkylation products are formed when metallic sodium is used instead of potassium. The interaction of ethene with the naphthalene-lithium system (24 h, Li:C10H8 = 2:1) affords 1 together with 1-n-butylnaphthalene (4), 1-n-hexylnaphthalene (5), 1-n-oktylnaphthalene (6) and dihydro derivatives of 5 and 6 in a total yield of 60%. Alkylation of toluene with ethene in the naphthalene-alkali metal systems leads to the formation of higher monoalkylbenzenes. The greatest toluene conversion (48%, 24 h) is observed on using the lithium-containing system (Li:C10H8 = 2:1), in the presence of which a mixture of n-propylbenzene (11), n-pentylbenzene (12), 3-phenylpentane (13) and 3-phenylheptane (14) is produced from ethene and toluene. On the replacement of lithium by sodium or potassium, only 11 and 13 are obtained. A treatment of biphenyl, phenanthrene, trans-stilbene, pyrene and anthracene with alkali metals in THF also gives systems capable of catalyzing the alkylation of toluene with ethene at 22 °C. Of particularly active is the stilbene-lithium system (Li:stilbene = 3:1) which converts toluene into a mixture of 11-14, n-heptylbenzene and 5-phenylnonane in a yield of 58%. In all cases, the rate of the alkylation considerably increases in the presence of the solid phase of alkali metal. The mechanism of the reactions found is discussed.
Equilibria of isomeric transformations and relations between thermodynamic properties of secondary alkylbenzenes
Pimerzin, A. A.,Nesterova, T. N.,Rozhnov, A. M.
, p. 641 - 648 (2007/10/02)
Equilibria of mutual transformations of monoamylbenzenes and diamylbenzenes (AmB), monohexylbenzenes (HxB), monoheptylbenzenes (HpB), and monodecylbenzenes (DB) have been studied in the liquid state over the range 273 to 423 K in the presence of 3 to 9 mass per cent of AlCl3.Values of ΔfH0m and ΔfS0m for the reactions studied have been calculated from the temperature dependences of the equilibrium constants.Below are given the reactions and the corresponding values for ΔfH0m/(kJ.mol-1) and ΔfS0m/(J.K-1.mol-1): 3-AmB=2-AmB, -(0.16 +/- 0.08), (8.45 +/- 0.23); 3-HxB=2-HxB, -(0.30 +/- 0.07), (3.85 +/- 0.21); 3-HpB=2-HpB, -(0.21 +/- 0.07), (3.52 +/- 0.22); 3-DB=2-DB, -(0.23 +/- 0.14), (3.51 +/- 0.43); 4-HpB=3-HpB, (0.02 +/- 0.41), (7.57 +/- 1.29); 4-DB=3-DB, (0.09 +/- 0.41), (1.69 +/- 1.28); 5-DB=4-DB, -(0.01 +/- 0.09), (0.18 +/- 0.25).For para-to-meta transformations of diamylbenzenes the average molar reaction enthalpy is -(0.26 +/- 0.46)kJ.mol-1 and the intrinsic change of molar entropy is -(0.99 +/- 1.2)J.K-1.mol-1.It is shown that for the calculation of enthalpies of formation of secondary alkylbenzenes correlations can be used which do not take into account the position of the phenyl substituent on the aliphatic hydrocarbon chain.The calculation of enthalpies of formation of normal and secondary alkylbenzenes in the liquid state at 298.15 K is made on the basis of experimental and literature values.
