- Ni-catalyzed reductive decyanation of nitriles with ethanol as the reductant
-
A nickel-catalyzed reductive decyanation of aromatic nitriles has been developed, in which the readily available and abundant ethanol was applied as the hydride donor. Various functional groups on the aromatic rings, such as alkoxyl, amino, imino and amide, were compatible in this catalytic protocol. Heteroaryl, benzylic and alkenyl nitriles were also tolerated. Mechanistic investigation indicated that ethanol provided hydride efficientlyviaβ-hydride elimination in this reductive decyanation.
- Wu, Ke,Ling, Yichen,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Jin, Liqun,Hu, Xinquan
-
supporting information
p. 2273 - 2276
(2021/03/09)
-
- A Highly Selective Manganese-Catalyzed Synthesis of Imines under Phosphine-Free Conditions
-
An efficient and highly selective phosphine-free NN-manganese(I) complex catalyst system was developed for the acceptorless dehydrogenative coupling of alcohols with amines to form imines. The coupling reactions underwent at 3 mol % catalyst loading, and a large range of alcohols and amines with diverse functional groups was applied, including challenging diol and diamine. The target imine products were obtained in good to excellent yields. The present work provides an alternative method to construct highly active nonprecious metal complex catalysts based on phosphine-free ligands.
- Chai, Huining,Yu, Kun,Liu, Bo,Tan, Weiqiang,Zhang, Guangyao
-
p. 217 - 226
(2020/01/31)
-
- Synthesis and molecular docking studies of imines as α-glucosidase and α-amylase inhibitors
-
Imine functionality is found in many compounds with important biological activity. Thus, the development of novel synthetic approaches for imines is important. In this work, it is propose an easy, eco-friendly and straightforward synthesis pathway of aryl imines under microwave irradiation catalyzed by Alumina-sulfuric acid. In addition, the in vitro enzymatic inhibition, antioxidant activity and molecular docking studies were performed. The aryl imines were isolated with yields in the range of 37–94%. All aryl imines synthesized were evaluated for in vitro inhibitory potential against α-glucosidase and α-amylase enzymes and the results exhibited that the most of the compounds displayed inhibitory activity against both enzymes. The (E)-1-(4-nitrophenyl)-N-(pyridin-2-yl)methanimine (3d) was 1.15-fold more active than acarbose against α-amylase whilst the (E)-1-phenyl-N-(pyridin-2-yl)methanimine (3c) displayed similar activity that acarbose against α-glucosidase. The molecular docking studies in α-glucosidase and α-amylase reveal that aryl imines mainly establish an H-bond with the R2-subtituent and hydrophobic interactions with the R1-subtituent. The docking analysis reveals these synthetic aryl imines 3d-i interact in same active site than acarbose drug in both enzymes.
- Aispuro-Pérez, Analy,Bastidas, Pedro,Calderón-Zamora, Loranda,García-Páez, Fernando,López-ávalos, Juan,Monta?o, Sarita,Montes-Avila, Julio,Ochoa-Terán, Adrián,Osuna-Martínez, Ulises,Picos-Corrales, Lorenzo A.,Sarmiento-Sánchez, Juan I.
-
-
- Ruthenium N-Heterocyclic Carbene Complexes for Chemoselective Reduction of Imines and Reductive Amination of Aldehydes and Ketones
-
Chemoselective reduction of imines to secondary amines is catalyzed efficiently by tethered and untethered, half-sandwich ruthenium N-heterocyclic carbene (NHC) complexes at room temperature. The untethered Ru-NHC complexes are more efficient as catalysts for the reduction of aldimines and ketimines than the tethered complexes. Using the best untethered complex as a catalyst, electronic and steric demands on the reaction was probed using a series of imines. Chemoselectivity of the catalyst towards imine reduction was tested by performing inter and intramolecular competitive reactions in a variety of ways. The catalyst exhibits a very high TON and TOF under anaerobic conditions.
- Kathuria, Lakshay,Samuelson, Ashoka G.
-
supporting information
(2020/06/17)
-
- A BEt3-Base catalyst for amide reduction with silane
-
Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
-
-
- A BEt3-Base Catalyst for Amide Reduction with Silane
-
Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
-
supporting information
p. 6084 - 6093
(2019/05/24)
-
- Aerobic Oxidative Homo- and Cross-Coupling of Amines Catalyzed by Phenazine Radical Cations
-
Phenazine radical cations (PhRCs) were used for the first time as efficient metal-free catalysts for the oxidative homo- and cross-coupling of a variety of different amines. A series of functional PhRCs were prepared, characterized with X-ray diffraction, and their radical character was investigated with DFT calculations. They were tested as catalysts under neat conditions with low oxygen pressure to prepare homo- and cross-coupled aliphatic and aromatic imines in high yields. Although all synthesized phenazines were catalytically active, the highest reaction rates and the best selectivity were achieved using the 5,10-dihydro-5,10-dimethylphenazine radical cation. By means of fluorescence, UV-vis and EPR spectroscopy, a mechanism of the oxidative amine coupling, catalyzed by PhRCs, is proposed.
- Bri?ar, Rok,Unglaube, Felix,Hollmann, Dirk,Jiao, Haijun,Mejía, Esteban
-
p. 13481 - 13490
(2018/11/02)
-
- Heterogeneous Sodium-Manganese Oxide Catalyzed Aerobic Oxidative Cleavage of 1,2-Diols
-
The aerobic oxidative cleavage of 1,2-diols using a heterogeneous catalyst only based on earth-abundant metals manganese and sodium is reported for the first time. This reusable catalyst cleaves a variety of substrates into aldehydes or ketones with high selectivity. The reaction requires small catalytic loadings and is performed under mild conditions using ambient pressure O2 or air as the oxidant while producing water as the only by-product. Mechanistic investigations reveal a monodentate, two-electron oxidative fragmentation process involving a MnIV species. The eco-friendly, innocuous catalyst is compatible with a wide range of functional groups and conditions, making it highly competitive with classical reagents, such as periodic acid or lead tetraacetate, as a preferred method for activated 1,2-diols.
- Escande, Vincent,Lam, Chun Ho,Coish, Philip,Anastas, Paul T.
-
supporting information
p. 9561 - 9565
(2017/08/01)
-
- Dynamic Covalent Organocatalysts Discovered from Catalytic Systems through Rapid Deconvolution Screening
-
The first example of a bifunctional organocatalyst assembled through dynamic covalent chemistry (DCC) is described. The catalyst is based on reversible imine chemistry and can catalyze the Morita-Baylis-Hillman (MBH) reaction of enones with aldehydes or N-tosyl imines. Furthermore, these dynamic catalysts were shown to be optimizable through a systemic screening approach, in which large mixtures of catalyst structures were generated, and the optimal catalyst could be directly identified by using dynamic deconvolution. This strategy allowed one-pot synthesis and in situ evaluation of several potential catalysts without the need to separate, characterize, and purify each individual structure. The systems were furthermore shown to catalyze and re-equilibrate their own formation through a previously unknown thiourea-catalyzed transimination process.
- Schaufelberger, Fredrik,Ramstr?m, Olof
-
supporting information
p. 12735 - 12740
(2015/09/01)
-
- Oxidation of secondary amines catalyzed by dirhodium caprolactamate
-
The dirhodium caprolactamate [Rh2(cap)4] catalyzed oxidation of secondary amines to imines by tert-butyl hydroperoxide (TBHP) occurs with high chemo- and regioselectivity. The Royal Society of Chemistry.
- Choi, Hojae,Doyle, Michael P.
-
p. 745 - 747
(2007/10/03)
-
- Eco-friendly synthesis of imines by ultrasound irradiation
-
A series of imines was synthesized by an ultrasound-assisted reaction of aldehydes and primary amines using silica as the promoter. Products were obtained in high yields even in large scale synthesis.
- Guzen, Karla P.,Guarezemini, Alexandre S.,órf?o, Aline T.G.,Cella, Rodrigo,Pereira, Claudio M.P.,Stefani, Hélio A.
-
p. 1845 - 1848
(2008/02/05)
-
- Synthesis and reactivity of trans-2-aryl-3-chloroazetidines
-
Several trans-2-aryl-3-chloroazetidines were synthesized in a stereoselective way by reduction of the corresponding β-lactams, which were formed by a Staudinger reaction using different benzaldimines and chloroketene. The resulting chloroazetidines proved to be excellent building blocks for the synthesis of different 3-substituted azetidines through nucleophilic substitution of the chlorine by different carbon, nitrogen, sulfur and oxygen nucleophiles in good to high yields. Since these substitution reactions took place with retention of stereochemistry, the intermediacy of bicyclic azonio[1.1.0]bicyclobutanes is proposed.
- Van Driessche, Berten,Van Brabandt, Willem,D'hooghe, Matthias,Dejaegher, Yves,De Kimpe, Norbert
-
p. 6882 - 6892
(2007/10/03)
-
- Effect of iminic nitrogen substituents on [4+2] versus [3+2] cycloaddition pathways in reactions of nitrosoalkenes with simple acyclic imines: An experimental and theoretical investigation
-
The results of experimental and theoretical investigations on the mechanism of competitive [3+2] versus [4+2] cycloaddition reactions of simple acyclic imines with nitrosoalkenes are reported. The effect of substituents on the iminic nitrogen in influencing the cycloaddition pathways has been meticulously explored.
- Marwaha, Alka,Bharatam,Mahajan
-
p. 8253 - 8256
(2007/10/03)
-
- Palladium-catalyzed allylation of imines with allyl alcohols
-
(Chemical Equation Presented) A catalytic system, Pd(OAc)2 (10 mol %)-P(n-Bu)3 (20 mol %)-Et3B (360 mol %), promotes allylic alcohols to undergo the allylation of anisidineimines of aromatic and aliphatic aldehydes and furnishes homoallylamines in good to moderate yields. The reaction shows unique stereoselectivity, giving anti-isomers selectively.
- Shimizu, Masamichi,Kimura, Masanari,Watanabe, Toshiya,Tamaru, Yoshinao
-
p. 637 - 640
(2007/10/03)
-
- Rearrangement of 2-aryl-3,3-dichloroazetidines: Intermediacy of 2-azetines
-
An easy synthesis of 2-aryl-3,3-dichloroazetidines, a rather unexplored class of azaheterocycles, is described. The title compounds were easily obtained by reduction of the corresponding 4-aryl-3,3-dichloro-2-azetidinones with monochloroalane, which in turn were synthesized by a ketene-imine [2 + 2] cycloaddition. The reactivity of 3,3-dichloroazetidines with bases was investigated, yielding 2-[dimethoxy(aryl)methyl]aziridines by ring contraction when treated with sodium methoxide. Furthermore, reacting the 3,3-dichloroazetidines with sodium hydride in DMSO, followed by aqueous workup, afforded 1-alkyl-2-aroylaziridines, by hydrolysis of the intermediate 2-azetines and ring closure of the transient 3-amino-2-chloro-1-phenyl-1-propanone derivatives. Monitoring this reaction in an NMR tube, using sodium hydride in DMSO-d6, allowed the characterization of the intermediate strained heterocyclic enamines, i.e., 2-azetines, by 1H and 13C NMR.
- Dejaegher, Yves,Mangelinckx, Sven,De Kimpe, Norbert
-
p. 2075 - 2081
(2007/10/03)
-
- Oxidation of various secondary amines to imines with N-tert-butylphenylsulfinimidoyl chloride
-
Various secondary amines were smoothly oxidized to the corresponding imines at -78 °C by using N-tert-butylphenylsulfinimidoyl chloride and DBU.
- Mukaiyama, Teruaki,Kawana, Asahi,Fukuda, Yoshio,Matsuo, Jun-Ichi
-
p. 390 - 391
(2007/10/03)
-
- Directed Metalation of Aromatic Aldimines with Lithium 2,2,6,6-Tetramethylpiperidide
-
N-Cyclohexyl aromatic aldimines are ortho-lithiated or o-methyl-lithiated with 2 equiv of lithium 2,2,6,6-tetramethylpiperidide (LTMP) in THF solution at -15 deg C.The lithiated intermediates generally reacted with alkyl halides or CO2 to provide ortho-functionalized aldimine products which could be readily converted to the corresponding aldehydes by hydrolysis with aqueous 4 M HCl.Aromatic aldimines derived from (+/-)-trans-2-methylcyclohexylamine or 3-amino-2,4-dimethylpentane are resistant toward C=N addition with 1 equiv of n-BuLi at 0 deg C in THF solution; however, they are also surprisingly resistant toward directed metalation reactions with either LTMP or n-BuLi.Exceptions to the ortho-directing and o-methyl-directing effects of the aldimine group were observed in a reaction of 3-methylthiophene-2-carboxaldehyde cyclohexylimine (7) with LTMP, followed by CH3I, which gave a 9:1 mixture of 3,5-dimethylthiophene-2-carboxaldehyde cyclohexylimine (22) and 5-ethyl-3-methylthiophene-2-carboxaldehyde cyclohexylimine (23), and a reaction of p-tolualdehyde 2,4-dimethylpent-3-ylimine (11) with either n-BuLi or LTMP, followed by CH3I, which gave p-ethylbenzaldehyde 2,4-dimethylpent-3-ylimine (25).
- Flippin, Lee A.,Muchowski, Joseph M.,Carter, David S.
-
p. 2463 - 2467
(2007/10/02)
-
- Boron Trifluoride Assisted Perfluoroalkylation of Carbon-Nitrogen Double Bonds
-
In the presence of BF3*OEt2, (perfluoroalkyl)lithiums generated in situ from the reaction of primary perfluoroalkyl iodides and MeLi-LiBr reacted with imines, azines, and nitrones to afford perfluoroalkylated nitrogen-containing compounds in moderate to good yields.This method was successfully applied to the preparation of a (perfluoroalkyl)glycine and optically active perfluoroalkylated amines.
- Uno, Hidemitsu,Okada, Shin-ichiro,Ono, Tetsushi,Shiraishi, Yasukazu,Suzuki, Hitomi
-
p. 1504 - 1513
(2007/10/02)
-
- A Route to Vicinal Diamines from the Samarium(II) Iodide-Mediated Coupling of Aldimines
-
A new method to construct vicinal diamines from aldimines mediated by the one electron reductant, samarium diiodide is described.The reaction probably involves a ketyl-like radical coupling mechanism.
- Enholm, Eric J.,Forbes, David C.,Holub, David P.
-
p. 981 - 987
(2007/10/02)
-
- Ready Decarboxylation of Imines of α-Keto Acids. Mechanism and Application to Thioamide Synthesis
-
α-Keto acids are readily decarboxylated via imine formation with primary and/or secondary amines even when imine-enamine isomerisation can occur; the process is thought to involve an intermediate zwitterion which can be trapped by sulphur to give thioamides in excellent yield.
- Aly, Moustafa F.,Grigg, Ronald
-
p. 1523 - 1524
(2007/10/02)
-