22920-61-2Relevant academic research and scientific papers
Implication of a Silyl Cobalt Dihydride Complex as a Useful Catalyst for the Hydrosilylation of Imines
Barbazanges, Marion,Bories, Cassandre C.,Derat, Etienne,Petit, Marc
, p. 14262 - 14273 (2021/11/27)
Here, we describe the formation and use of silyl cobalt (III) dihydride complexes as powerful catalysts for the hydrosilylation of a variety of imines starting from a low-valent well-defined cobalt (I) complex. The reaction is efficient at low catalyst loadings with a diverse range of imines bearing various protecting groups, as well as aliphatic ketimines and quinoline. Kinetics, DFT calculations, NMR spectroscopic studies, deuteration experiments, and X-ray diffraction analyses allowed us to propose a catalytic cycle based on silyl dihydrocobalt (III) complexes performing a hydrocobaltation.
Iron-catalysed 1,2-aryl migration of tertiary azides
Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
supporting information, p. 11685 - 11688 (2020/10/19)
1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
Improving C=N bond reductions with (Cyclopentadienone)iron complexes: Scope and limitations
Cettolin, Mattia,Bai, Xishan,Lübken, Dennis,Gatti, Marco,Facchini, Sofia Vailati,Piarulli, Umberto,Pignataro, Luca,Gennari, Cesare
, p. 647 - 654 (2018/10/24)
Herein, we broaden the application scope of (cyclo-pentadienone)iron complexes 1 in C=N bond reduction. The catalytic scope of pre-catalyst 1b, which is more active than the “Kn?lker complex” (1a) and other members of its family, has been expanded to the catalytic transfer hydrogenation (CTH) of a wider range of aldimines and ketimines, either pre-isolated or generated in situ. The kinetics of 1b-promoted CTH of ketimine S1 were assessed, showing a pseudo-first order profile, with TOF = 6.07 h–1 at 50 % conversion. Moreover, the chiral complex 1c and its analog 1d were employed in the enantioselective reduction of ketimines and reductive amination of ketones, giving fair to good yields and moderate enantioselectivity.
Borane-Catalyzed Chemoselectivity-Controllable N-Alkylation and ortho C-Alkylation of Unprotected Arylamines Using Benzylic Alcohols
Meng, Shan-Shui,Tang, Xiaowen,Luo, Xiang,Wu, Ruibo,Zhao, Jun-Ling,Chan, Albert S. C.
, p. 8397 - 8403 (2019/09/03)
An unprecedented protocol for the efficient and highly chemoselective alkylation of unprotected arylamines using alcohols catalyzed by B(C6F5)3 has been developed. The reaction gives N-alkylated products and ortho C-alkylated products in different solvents in good chemoselectivities and yields. Control experiments and DFT calculations indicated that the borane underwent alcohol/arylamine exchange to ensure catalytic activity, and a possible mechanism involving a carbocation is proposed.
Efficient Synthesis of Amines by Iron-Catalyzed C=N Transfer Hydrogenation and C=O Reductive Amination
Facchini, Sofia Vailati,Cettolin, Mattia,Bai, Xishan,Casamassima, Giuseppe,Pignataro, Luca,Gennari, Cesare,Piarulli, Umberto
supporting information, p. 1054 - 1059 (2018/01/27)
Here we report the catalytic transfer hydrogenation (CTH) of non-activated imines promoted by a Fe-catalyst in the absence of Lewis acid co-catalysts. Use of the (cyclopentadienone)iron complex 1, which is much more active than the classical ‘Kn?lker complex’ 2, allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5–2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this methodology, we developed a one-pot CTH protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates. (Figure presented.).
Enhanced Catalytic Activity of Oxygen-Tethered IrIII NHC Complexes in Aqueous Transfer Hydrogenative Reductive Amination Reactions: Experimental Kinetic and Mechanistic Study
?zbozkurt, ?brahim Kayahan,Gülcemal, Derya,Günnaz, Salih,G?k?e, Ayta? Gürhan,?etinkaya, Bekir,Gülcemal, Süleyman
, p. 3593 - 3604 (2018/08/03)
The synthesis and characterization of seven new IrIII complexes containing o-phenoxide or o-naphthoxide chelated N-heterocyclic carbene ligands is reported herein. The crystal structures of six of the complexes have been determined. These complexes efficiently catalyze the transfer hydrogenative reductive amination (RA) of carbonyls and amines in water. Amongst the complexes tested, the introduction of o-naphthoxide on a nitrogen atom of imidazole based NHC ligand greatly increased the catalytic activity. The catalytic system has a broad substrate scope, which allows the synthesis of a variety of amines in excellent yields and with high turnover numbers up to 490 (for ketones) and 14800 (for aldehydes). The mechanism of aqueous RA reaction with an o-aryloxide chelated NHC-IrIII catalyst has been investigated by NMR spectroscopy and kinetic measurements. These studies suggest that the transfer hydrogenation (TH) is turnover-limited by the hydride formation step. As a result of the 1H NMR studies, the higher catalytic activity of o-naphthoxide chelated catalyst (3 g) over o-phenoxide chelated one (3 b) can be attributed partly due to the faster formation of an iridium hydride, the key intermediate in the RA reactions.
Cyclometalated palladium pre-catalyst for N-alkylation of amines using alcohols and regioselective alkylation of sulfanilamide using aryl alcohols
Mamidala, Ramesh,Mukundam, Vanga,Dhanunjayarao, Kunchala,Venkatasubbaiah, Krishnan
supporting information, p. 2225 - 2233 (2017/03/24)
Simple pyrazole based palladacycle-phosphine with a high turnover has been developed and applied for the N-alkylation of amines and sulfanilamide using alcohols as substrates by hydrogen borrowing strategy. N-alkylation of primary and secondary amines resulted in high isolated yields at 100–130 °C, under solvent free conditions. More challenging secondary aliphatic as well as aromatic alcohols were also successfully utilized as alkylating agents under similar reaction conditions. The turn over number reached up to 43000 for N-benzylation of aniline using benzyl alcohol. Notably, regioselective N-alkylation of 2-aminobenzothiazole and 4-aminobenzenesulfonamide to the corresponding 2-N-(alkylamino)azoles and 4-amino-(N-alkyl)benzenesulfonamides using alcohols as alkylating agents have been achieved using our new pre-catalyst-phosphine system.
Solvent- and catalyst-free direct reductive amination of aldehydes and ketones with Hantzsch ester: Synthesis of secondary and tertiary amines
Nguyen, Quynh Pham Bao,Kim, Taek Hyeon
, p. 4938 - 4943 (2013/07/25)
A facile and rapid method for the parallel synthesis of a series of secondary and tertiary amines by the direct reductive amination of aldehydes and ketones with Hantzsch ester under solvent- and catalyst-free has been developed. The scope and limitation of this method are described.
S-benzyl isothiouronium chloride as a recoverable organocatalyst for the direct reductive amination of ketones with Hantzsch ester
Nguyen, Quynh Pham Bao,Kim, Taek Hyeon
experimental part, p. 1977 - 1982 (2012/08/07)
The direct reductive amination of ketones using the Hantzsch ester in the presence of S-benzyl isothiouronium chloride as a recoverable organocatalyst is reported. A wide range of ketones as well as amines were found to give the expected products in moder
Trifluoromethanesulfonic acid as an efficient catalyst in the reduction of ketimines
Li, Jianhui,Wang, Zhouyu,Jiang, Zhenju,Jiang, Shengqian
experimental part, p. 3101 - 3103 (2012/01/06)
Trifluoromethanesulfonic acid was found to be highly efficient catalyst in the reduction of ketimines with Hantzsh esters as the hydrogen source. The catalyst loading could be decreased to 1 mol %. Moderate to excellent isolated yields (up to 99 %) were obtained under mild conditions.
