24374-32-1Relevant academic research and scientific papers
Copper-Catalyzed C(sp3)?H Amidation: Sterically Driven Primary and Secondary C?H Site-Selectivity
Bakhoda, Abolghasem (Gus),Jiang, Quan,Badiei, Yosra M.,Bertke, Jeffery A.,Cundari, Thomas R.,Warren, Timothy H.
supporting information, p. 3421 - 3425 (2019/02/14)
Undirected C(sp3)?H functionalization reactions often follow site-selectivity patterns that mirror the corresponding C?H bond dissociation energies (BDEs). This often results in the functionalization of weaker tertiary C?H bonds in the presence of stronger secondary and primary bonds. An important, contemporary challenge is the development of catalyst systems capable of selectively functionalizing stronger primary and secondary C?H bonds over tertiary and benzylic C?H sites. Herein, we report a Cu catalyst that exhibits a high degree of primary and secondary over tertiary C?H bond selectivity in the amidation of linear and cyclic hydrocarbons with aroyl azides ArC(O)N3. Mechanistic and DFT studies indicate that C?H amidation involves H-atom abstraction from R-H substrates by nitrene intermediates [Cu](κ2-N,O-NC(O)Ar) to provide carbon-based radicals R. and copper(II)amide intermediates [CuII]-NHC(O)Ar that subsequently capture radicals R. to form products R-NHC(O)Ar. These studies reveal important catalyst features required to achieve primary and secondary C?H amidation selectivity in the absence of directing groups.
Copper-catalyzed intermolecular amidation and imidation of unactivated alkanes
Tran, Ba L.,Li, Bijie,Driess, Matthias,Hartwig, John F.
supporting information, p. 2555 - 2563 (2014/03/21)
We report a set of rare copper-catalyzed reactions of alkanes with simple amides, sulfonamides, and imides (i.e., benzamides, tosylamides, carbamates, and phthalimide) to form the corresponding N-alkyl products. The reactions lead to functionalization at secondary C-H bonds over tertiary C-H bonds and even occur at primary C-H bonds. [(phen)Cu(phth)] (1-phth) and [(phen)Cu(phth)2] (1-phth2), which are potential intermediates in the reaction, have been isolated and fully characterized. The stoichiometric reactions of 1-phth and 1-phth2 with alkanes, alkyl radicals, and radical probes were investigated to elucidate the mechanism of the amidation. The catalytic and stoichiometric reactions require both copper and tBuOOtBu for the generation of N-alkyl product. Neither 1-phth nor 1-phth2 reacted with excess cyclohexane at 100 C without tBuOOtBu. However, the reactions of 1-phth and 1-phth2 with tBuOOtBu afforded N-cyclohexylphthalimide (Cy-phth), N-methylphthalimide, and tert-butoxycyclohexane (Cy-OtBu) in approximate ratios of 70:20:30, respectively. Reactions with radical traps support the intermediacy of a tert-butoxy radical, which forms an alkyl radical intermediate. The intermediacy of an alkyl radical was evidenced by the catalytic reaction of cyclohexane with benzamide in the presence of CBr4, which formed exclusively bromocyclohexane. Furthermore, stoichiometric reactions of [(phen)Cu(phth)2] with tBuOOtBu and (Ph(Me)2CO) 2 at 100 C without cyclohexane afforded N-methylphthalimide (Me-phth) from β-Me scission of the alkoxy radicals to form a methyl radical. Separate reactions of cyclohexane and d12-cyclohexane with benzamide showed that the turnover-limiting step in the catalytic reaction is the C-H cleavage of cyclohexane by a tert-butoxy radical. These mechanistic data imply that the tert-butoxy radical reacts with the C-H bonds of alkanes, and the subsequent alkyl radical combines with 1-phth2 to form the corresponding N-alkyl imide product.
Inter- and intramolecular hydroamination of unactivated alkenes catalysed by a combination of copper and silver salts: The unveiling of a Bronstedt acid catalysis
Michon, Christophe,Medina, Florian,Capet, Frederic,Roussel, Pascal,Agbossou-Niedercorn, Francine
supporting information; experimental part, p. 3293 - 3305 (2011/02/23)
The combined use of a copper halide, a silver salt and a phosphane ligand was applied for the catalysis of inter- and intramolecular hydroamination of alkenes. The reactions of unactivated olefins with nitrogen substrates were investigated. Mechanistic investigations demonstrated that the catalytic system generated a Bronsted acid which appeared to be the prominent catalytic species. Copyright
Amberlyst-15 in ionic liquid: An efficient and recyclable reagent for nucleophilic substitution of alcohols and hydroamination of alkenes
Qureshi, Ziyauddin S.,Deshmukh, Krishna M.,Tambade, Pawan J.,Dhake, Kishor P.,Bhanage, Bhalchandra M.
experimental part, p. 6233 - 6238 (2010/12/25)
The nucleophilic substitution reaction of secondary alcohols and hydroamination of alkenes with amides, sulfonamides, carbamates, and amines using Amberlyst-15 immobilized in [Bmim][BF4] (1-butyl-3- methylimidazolium tetrafluoroborate) ionic liquid as an efficient recyclable reagent is described. The solvent effect is prominent in the reaction, and the desired substitution products are obtained in good to excellent yield. The protocol is advantageous due to the ease of handling of the reagents, the simple work-up procedure, and the environmentally benign conditions that allow effective recyclability. A facile protocol involving Amberlyst-15 in the ionic liquid [Bmim][BF4] (= 1-butyl-3-methylimidazolium tetrafluoroborate) has been developed for nucleophilic substitution of alcohols and hydroamination of alkenes.
Highly efficient and reusable ionic liquids for the catalyzed hydroamination of alkenes with sulfonamides, carbamates, and carboxamides
Yang, Lei,Xu, Li-Wen,Xia, Chun-Gu
experimental part, p. 1969 - 1974 (2009/12/26)
SO3H-Functionalized ionic liquids were found to be efficient and reusable catalysts in the hydroamination of sulfonamides, carboxamides, p-nitroaniline and carbamates with nonactivated alkenes. The hydroamination could be performed on a large scale and the acidic ionic liquid catalyst could be reused successfully. Georg Thieme Verlag Stuttgart.
Zirconium-catalyzed intermolecular hydroamination of unactivated olefins
Yang, Lei,Xu, Li-Wen,Zhou, Wei,Gao, Yue-Hua,Sun, Wei,Xia, Chun-Gu
scheme or table, p. 1167 - 1171 (2009/09/25)
Highly efficient hydroamination reactions of sulfonamides, carboxamides, and carbamates with unactivated olefins catalyzed by simple and inexpensive zirconium salts under mild reaction conditions were presented for the practical preparation of various amines. These processes gave good to excellent yields of the addition products in Markovnikov addition fashion. Georg Thieme Verlag Stuttgart.
Heteropoly acids: a green and efficient heterogeneous Br?nsted acidic catalyst for the intermolecular hydroamination of olefins
Yang, Lei,Xu, Li-Wen,Xia, Chun-Gu
, p. 2882 - 2885 (2008/09/21)
Intermolecular hydroamination of non-activated olefins with amides and benzyl carbamate proceeds efficiently in the presence of environmentally benign silicotungstic acid (HSiW) catalyst under mild conditions in air to afford addition products in good to excellent yields.
Mechanistic studies of the hydroamination of norbornene with electrophilic platinum complexes: The role of proton transfer
McBee, Jennifer L.,Bell, Alexis T.,Don Tilley
scheme or table, p. 16562 - 16571 (2009/04/14)
Hydroaminations of norbornene with arylsulfonamides and weakly basic anilines were achieved using electrophilic Pt(II) bis(triflate) complexes of the type L2Pt(OTf)2 (L2 = tBu 2bpy, tBuC6H4N= C(CH 3)C(CH3)=NC6H4tBu, (C6H5)2PCH2CH2P(C 6H5)2, (C6F5) 2PCH2CH2P(C6F5) 2, S-BINAP). Pseudo-first-order kinetics reveal little to no dependence of the reaction rate on the ancillary ligand. Mechanistic studies do not favor an olefin coordination mechanism but are instead consistent with a mechanism involving sulfonamide coordination and generation of an acidic proton that is transferred to the norbornene. It is postulated that the resulting norbornyl cation is then attacked by free sulfonamide, and loss of proton from this adduct completes the hydroamination. The platinum-sulfonamide complex readily undergoes deprotonation to give μ-amido platinum-bridged dimer that was isolated from the reaction solution. These studies also involve use of Me3SiPh and Me3SnPh as non-nucleophilic proton traps. Cleavage of the Ph-E bonds was used to detect the acidic, catalytically active species.
Radical transfer hydroamination with aminated cyclohexadienes using polarity reversal catalysis: Scope and limitations
Guin, Joyram,Mueck-Lichtenfeld, Christian,Grimme, Stefan,Studer, Armido
, p. 4498 - 4503 (2008/02/03)
The synthesis of various new 1-aminated-2,5-cyclohexadienes is described. These reagents can be used in radical transfer hydroaminations of unactivated and electron-rich double bonds. With thiols as polarity reversal catalysts good yields are obtained. The radical hydroamination occurs with good to excellent anti-Markovnikov selectivity. Many functional groups such as alcohols, silyl ethers, phosphonates, arylbromides, imides, amides, and also acidic protons are tolerated under the reaction conditions. DFT calculations provide insights into the aromatization of silyl, alkyl, and aminyl substituted cyclohexadienyl radicals to generate the corresponding C-, Si-, and N-centered radicals.
Mechanistic studies of the copper-catalyzed electrophilic amination of diorganozinc reagents and development of a zinc-free protocol
Campbell, Matthew J.,Johnson, Jeffrey S.
, p. 1521 - 1524 (2008/02/02)
Equation Presented An SN2 mechanism for the copper-catalyzed amination of diorganozinc reagents by O-benzoyl-N,N-dialkylhydroxyamines is supported by following stereochemically defined organometallics through the reaction and by employing the endocyclic restriction test. A copper-catalyzed electrophilic amination of organomagnesium compounds is also described in which the use of zinc halides has been eliminated.
