- Base-Catalyzed [3 + 2] Cycloaddition of N-Benzyl Ketimines to Arylacetylenes Followed by Oxidation: A One-Pot Access to Polyarylated 2 H-Pyrroles via Intermediate Pyrrolines
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N-Benzyl ketimines undergo [3 + 2] cycloaddition with arylacetylenes in the KOBut/DMSO solution to 2,3,5-triarylpyrrolines, which are oxidized (chloranil, DDQ) in situ to 2,3,5-triaryl-2H-pyrroles in 53-71% yields. The intermediate 1-pyrrolines can be isolated in 31-91% yields and separately oxidized to the corresponding 2H-pyrroles.
- Bidusenko, Ivan A.,Schmidt, Elena Yu.,Trofimov, Boris A.,Ushakov, Igor A.,Vashchenko, Alexander V.
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supporting information
p. 4121 - 4126
(2021/06/28)
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- Direct C(sp3)-N Radical Coupling: Photocatalytic C-H Functionalization by Unconventional Intermolecular Hydrogen Atom Transfer to Aryl Radical
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An unconventional approach for intermolecular direct C(sp3)-N radical coupling has been developed by photocatalytic C(sp3)-H activation of simple alkyl substrates using O-benzoyl oximes. The selective photocatalytic energy-transfer-driven homolysis followed by decarboxylation generates the persistent iminyl radical and aryl radical, which would undergo an unprecedented intermolecular hydrogen atom abstraction from the alkyl substrate to provide the key C(sp3) radical. Selective radical-radical C-N cross-coupling furnishes imines which are valuable amine building blocks.
- Cho, Eun Jin,Hwang, Ho Seong,Kang, Jihee,Soni, Vineet Kumar
-
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- Palladium-Catalyzed Diarylation of Isocyanides with Tetraarylleads for the Selective Synthesis of Imines and α-Diimines
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Using tetraaryllead compounds (PbAr4) as arylating reagents, isocyanides undergo selective diarylation in the presence of palladium catalysts such as Pd(OAc)2 or Pd(PPh3)4 to afford imines and/or α-diimines based on the isocyanide employed. With aliphatic isocyanides, imines are obtained preferentially, whereas α-diimines are formed in the case of electron-rich aromatic isocyanides. The differences in imine/α-diimine selectivity can be attributed to the stability of imidoylpalladium intermediates formed in this catalytic reaction. Compared with other arylating reagents, tetraaryllead compounds are excellent candidates for use in the selective transformations to imines and/or α-diimines, especially in terms of inhibiting the oligomerization of isocyanides, which results in a lower product selectivity in many transition-metal-catalyzed reactions of isocyanides.
- Tran, Cong Chi,Kawaguchi, Shin-Ichi,Kobiki, Yohsuke,Matsubara, Hitomi,Tran, Dat Phuc,Kodama, Shintaro,Nomoto, Akihiro,Ogawa, Akiya
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p. 11741 - 11751
(2019/10/02)
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- Visible-Light-Mediated Umpolung Reactivity of Imines: Ketimine Reductions with Cy2NMe and Water
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A novel carbanionic reactivity of imines mediated by photoredox catalysis is demonstrated. The umpolung imine reactivity is exemplified by proton abstraction from water as a key step in the reduction of benzophenone ketimines to amines (up to 98% yield). Deuterium is introduced into amines efficiently using D2O as an inexpensive deuterium source (≥95% D ratio). The mechanism of this unusual transformation is probed.
- Wang, Rui,Ma, Mengyue,Gong, Xu,Panetti, Grace B.,Fan, Xinyuan,Walsh, Patrick J.
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supporting information
p. 2433 - 2436
(2018/04/27)
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- Photocatalytic and Chemoselective Transfer Hydrogenation of Diarylimines in Batch and Continuous Flow
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A visible-light photocalytic method for the chemoselective transfer hydrogenation of imines in batch and continuous flow is described. The reaction utilizes Et3N as both hydrogen source and single-electron donor, enabling the selective reduction of imines derived from diarylketimines containing other reducible functional groups including nitriles, halides, esters, and ketones. The dual role of Et3N was confirmed by fluorescence quenching measurements, transient absorption spectroscopy, and deuterium-labeling studies. Continuous-flow processing facilitates straightforward scale-up of the reaction.
- Van As, Dean J.,Connell, Timothy U.,Brzozowski, Martin,Scully, Andrew D.,Polyzos, Anastasios
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supporting information
p. 905 - 908
(2018/02/22)
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- Benzhydrylamine: An effective aminating agent for the synthesis of primary amines
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Aldehydes, ketones, alkyl toluene-p-sulfonates and halides are converted into the corresponding primary amines with benzhydrylamine as a valuable ammonia synthon in moderate to excellent yields.
- Sun, Quan-Wei,Xing, Jun-De,Qin, Yu-Hong,Yin, Xu-Wen,Zhou, Yi
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p. 181 - 183
(2018/05/26)
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- P-N Cooperative Borane Activation and Catalytic Hydroboration by a Distorted Phosphorous Triamide Platform
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Studies of the stoichiometric and catalytic reactivity of a geometrically constrained phosphorous triamide 1 with pinacolborane (HBpin) are reported. The addition of HBpin to phosphorous triamide 1 results in cleavage of the B-H bond of pinacolborane through addition across the electrophilic phosphorus and nucleophilic N-methylanilide sites in a cooperative fashion. The kinetics of this process of were investigated by NMR spectroscopy, with the determined overall second-order empirical rate law given by ν = -k[1][HBpin], where k = 4.76 × 10-5 M-1 s-1 at 25 °C. The B-H bond activation process produces P-hydrido-1,3,2-diazaphospholene intermediate 2, which exhibits hydridic reactivity capable of reacting with imines to give phosphorous triamide intermediates, as confirmed by independent synthesis. These phosphorous triamide intermediates are typically short lived, evolving with elimination of the N-borylamine product of imine hydroboration with regeneration of the deformed phosphorous triamide 1. The kinetics of this latter process are shown to be first-order, indicative of a unimolecular mechanism. Consequently, catalytic hydroboration of a variety of imine substrates can be realized with 1 as the catalyst and HBpin as the terminal reagent. A mechanistic proposal implicating a P-N cooperative mechanism for catalysis that incorporates the various independently verified stoichiometric steps is presented, and a comparison to related phosphorus-based systems is offered.
- Lin, Yi-Chun,Hatzakis, Emmanuel,McCarthy, Sean M.,Reichl, Kyle D.,Lai, Ting-Yi,Yennawar, Hemant P.,Radosevich, Alexander T.
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supporting information
p. 6008 - 6016
(2017/05/04)
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- Synthesis of 4-Isoxazolines via Visible-Light Photoredox-Catalyzed [3 + 2] Cycloaddition of Oxaziridines with Alkynes
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A method for [3 + 2] cycloaddition of oxaziridines with alkynes to form 4-isoxazolines via visible-light photoredox catalysis is described. This method is a greener, atom-economical reaction that tolerates various functional groups and provides good to excellent yield. Moreover, the cyclization products can be conveniently converted into tetrasubstituted allylic alcohols and enamines. A mechanistic study suggests that the reaction involves photoredox-catalyzed in situ generation of a nitrone from the oxaziridine by SET.
- Jang, Gwang Seok,Lee, Junggeun,Seo, Jungseok,Woo, Sang Kook
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supporting information
p. 6448 - 6451
(2017/12/08)
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- Access to α-Arylglycines by Umpolung Carboxylation of Aromatic Imines with Carbon Dioxide
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A straightforward and transition-metal-free approach for the efficient synthesis of α-arylglycine derivatives from aromatic imines and carbon dioxide was enabled by an umpolung carboxylation reaction. Various substituted diphenylmethimines underwent the carboxylation smoothly with carbon dioxide in the presence of potassium tert-butoxide and 18-crown-6 to give the corresponding carboxylated products in good to high yields. Besides the enhancement of the solubility of potassium tert-butoxide in THF, 18-crown-6 also plays key roles in suppressing the reverse protonation or 1, 3-proton shift isomerization as well as by stabilizing the carboxylated intermediate.
- Guo, Chun-Xiao,Zhang, Wen-Zhen,Zhou, Hui,Zhang, Ning,Lu, Xiao-Bing
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p. 17156 - 17159
(2016/11/23)
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- Cyclopalladated benzophenone imines: Synthesis, antitumor activity, cell accumulation, dna interaction, and cathepsin b inhibition
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The synthesis of the endo five-membered cyclo-ortho-palladated benzophenone imines [Pd{C6H4(Ph)C=NR}]2(μ-X)2 [1 (X = OAc), 2 (X = Cl), a (R = phenyl), b (R = 1-naphthyl), c (R = benzyl), d (R = α-methylbenzyl)], and trans-N,P-[Pd{C6H4(Ph)C=NR}X(PPh3)] [3 (X = OAc), 4 (X = Cl), a (R = phenyl), b (R = 1-naphthyl), c (R = benzyl), d (R = α-methylbenzyl)] and the X-ray molecular structure of 1a, 1c, 1d, 4a, 4b, and 4c are reported. The antitumor activity, DNA interaction, and cathepsin B inhibition of palladium compounds a-d were studied and compared with those previously reported for palladium compounds e with R = H and compound 4f analogous to 4e but with a platinum(II) center. The IC50 values against a panel of human cancer cell lines allowed the establishment of a qualitative relationship between their structure and antitumor activity. Compounds 3e, 4e, and 4f were the most active ones in relation to their in vitro anticancer activity. Compounds 3e and 4e were about 4 times more active than cisplatin against the MDA-MB-231 and MCF-7 breast human cancer lines, and compound 4f was about 4 times more active than cisplatin against the cisplatin-resistant HCT-116 colon human cancer cell line. In addition, compound 3e was 3 times less cytotoxic than cisplatin toward the quiescent HUVEC cells. Accumulation of palladium compounds e and b in the MDA-MB-231 cell line was considerably greater than that of cisplatin in the same cell line, but palladium compounds b were noncytotoxic. Some of these complexes altered the DNA tertiary structure in a similar way to cisplatin but at higher concentration, and most cytotoxic ones did not present a high efficiency as cathepsin B inhibitors.
- Albert, Joan,Granell, Jaume,Qadir, Romana,Quirante, Josefina,Calvis, Carme,Messeguer, Ramon,Bada, Josefa,Baldom, Laura,Font-Bardia, Merc,Calvet, Teresa
-
supporting information
p. 7284 - 7292
(2015/03/03)
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- Rh(III)-catalyzed synthesis of 1-substituted isoquinolinium salts via a C-H bond activation reaction of ketimines with alkynes
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An efficient synthesis of highly substituted isoquinolinium salts from ketimines and alkynes via a Rh(III)-catalyzed C-H bond activation and annulation reaction is described. The Royal Society of Chemistry.
- Senthilkumar, Natarajan,Gandeepan, Parthasarathy,Jayakumar, Jayachandran,Cheng, Chien-Hong
-
supporting information
p. 3106 - 3108
(2014/03/21)
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- Catalytic acceptorless dehydrogenations: Ru-Macho catalyzed construction of amides and imines
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A commercially available ruthenium(II) PNP type pincer catalyst (Ru-Macho) promotes formation of amides and imines from alcohols and amines via an acceptorless dehydrogenation pathway. The formation of secondary amides, tertiary amides, and secondary ketimines occurs in yields ranging from 35% to 95%.
- Oldenhuis, Nathan J.,Dong, Vy M.,Guan, Zhibin
-
supporting information
p. 4213 - 4218
(2014/06/09)
-
- Taking the F out of FLP: Simple lewis acid-base pairs for mild reductions with neutral boranes via borenium ion catalysis
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Discrete three-coordinate borenium salts 1c and 1d are accessed by cooperative Lewis acid-base pair-mediated heterolytic splitting of the B-H bond in pinacolborane by B(C6F5)3DABCO and Ph 3C+/DABCO, respectively. The resulting salts are competent catalysts in the reduction of a broad range of imines and can be generated in situ. Moreover, a mechanistic framework for borenium catalysis based on experimental evidence is proposed. The reaction is suggested to proceed by borenium activation of the imine substrate followed by counterintuitive hydride delivery from HBPin (with the assistance of DABCO) rather than from the HB(C6F5)3- anion, contrary to typical mechanisms of reduction in FLP systems.
- Eisenberger, Patrick,Bailey, Adrian M.,Crudden, Cathleen M.
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p. 17384 - 17387
(2013/01/15)
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- Carbon-carbon bond formations at the benzylic positions of N-benzylxanthone imines and N-benzyldi-1-naphthyl ketone imine
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Two N-benzyl imines are designed to allow for carbon-carbon bond formations at the aminated benzylic positions. Direct benzylic arylation reactions of N-benzylxanthone imine with aryl chlorides proceed under palladium catalysis in the presence of cesium hydroxide, yielding the corresponding benzhydrylamine derivatives. Alkylation reactions of N-benzyldi-1-naphthyl ketone imine with alkyl halides in the presence of potassium tert-butoxide afford the corresponding 1-phenylalkylamines in high yields. Conjugate addition of N-benzyldi-1-naphthyl ketone imine is also described.
- Niwa, Takashi,Suehiro, Takafumi,Yorimitsu, Hideki,Oshima, Koichiro
-
experimental part
p. 5125 - 5131
(2009/11/30)
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- Rhenium-catalyzed synthesis of naphthalene derivatives via insertion of aldehydes into a C-H bond
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A rhenium complex, [ReBr(CO)3(THF)]2, catalyzed reactions of aromatic ketimines and aldehydes with dienophiles, followed by dehydration, to give naphthalene derivatives in good to excellent yields. This reaction proceeds via C-H bond activation, insertion of an aldehyde, intramolecular nucleophilic cyclization, reductive elimination, elimination of aniline and Diels-Alder reaction. After dehydration, naphthalene derivatives were formed.
- Kuninobu, Yoichiro,Nishina, Yuta,Takai, Kazuhiko
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p. 8463 - 8468
(2008/02/09)
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- Silica gel supported sodium hydrogen sulfate as an efficient and reusable heterogeneous catalyst for the synthesis of imines in solvent-free conditions under microwave irradiation
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This synthesis of imines has been carried out efficiently by the condensation of carbonyl compounds with amines in the presence of silica gel supported sodium hydrogen sulfate (NaHSO4.SiO2) as a heterogeneous catalyst under microwave irradiation in solvent-free conditions. NaHSO4.SiO2 can be recovered and re-used up to ten times by simple washing with diethyl ether after each use and activated in an oven at 120°C for 1 h, thus rendering the process more economical.
- Gopalakrishnan, Mannathusamy,Sureshkumar, Purushothaman,Kanagarajan, Vijayakumar,Thanusu, Jeyaraman,Govindaraju, Ramalingam
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p. 299 - 303
(2007/10/03)
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- The simple and selective synthesis of 3-amino-2,2-difluorocarboxylic esters and difluoro-β-lactams using ethyl bromodifluoroacetate in the presence of rhodium catalyst
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Treatment of imines (5) with ethyl bromodifluoroacetate (1) and Et 2Zn in the presence of RhCl(PPh3)3 in anhydrous medium gave difluoro-β-lactams (7) in good to excellent yields, while 3-amino-2,2-difluorocarboxylic esters (6) were obtained in good yields by adding MgSO4·7H2O to the reaction medium.
- Sato, Kazuyuki,Tarui, Atsushi,Matsuda, Seiji,Omote, Masaaki,Ando, Akira,Kumadaki, Itsumaro
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p. 7679 - 7681
(2007/10/03)
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- Magnesium perchlorate as an efficient catalyst for the synthesis of imines and phenylhydrazones
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Magnesium perchlorate has been found to be an efficient catalyst for the synthesis of imines and phenylhydrazones by the reaction of carbonyl compounds with amines and phenylhydrazine in high yields at room temperatures and in short times. The condensation of less electrophilic carbonyl compounds with poorly nucleophilic amines affords the imines in excellent yields.
- Chakraborti, Asit K.,Bhagat, Srikant,Rudrawar, Santosh
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p. 7641 - 7644
(2007/10/03)
-
- Lanthanide triflate catalysed reactions of acetals with primary amines and cascade cyclisation reactions
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The formation of imines from acetals and primary amines can be carried out at significantly lower temperatures using scandium or lanthanide triflates as catalysts, than in the absence of a catalyst: the intermediate aminol ethers can also take part in cascade cyclisation reactions, for example using tryptamine and ethyl tryptophanate.
- Heaney, Harry,Simcox, Michael T.,Slawin, Alexandra M.Z.,Giles, Robert G.
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p. 640 - 642
(2007/10/03)
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- A practical one-pot synthesis of trans-4,5-disubstituted 2-pyrrolidinones and the related pyrrolidines
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A practical and general method for the stereoselective synthesis of trans-4,5-disubstituted 2-pyrrolidinones was developed. Hydride reduction of these pyrrolidinones gave the corresponding pyrrolidines.
- Yee, Nathan K.
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p. 5091 - 5094
(2007/10/03)
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- Efficient transamination under mild conditions: Preparation of primary amine derivatives from carbonyl compounds via imine isomerization with catalytic amounts of potassium tert-butoxide
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1,3-Prototropic rearrangement of N-diphenylmethanimines was successfully performed with a catalytic amount of potassium tert-butoxide. This procedure can also be used with aliphatic and aromatic aldimines and was extended to the isomerization of (1R)-camphorquinone monoimine and N-(4-methoxyphenyl)-4-phenyl-3-iminoazetidin-2-one. The isomerized imines were easily hydrolyzed and isolated as Cbz derivatives.
- Cainelli, Gianfranco,Giacomini, Daria,Trerè, Alessandra,Boyl, Pietro Pilo
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p. 5134 - 5139
(2007/10/03)
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- A simple and inexpensive method for the preparation of imines and azadienes
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A number of imines and azadienes were prepared in high yield and good purity by using the condensation reactions of various aldehydes and ketones with amines over natural Algerian bentonite.
- Saoudi,Benguedach,Benhaoua
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p. 2349 - 2354
(2007/10/02)
-
- CRYPTATE ACIDITY SCALES. VI. EFFECT OF POLARITY OF THE MEDIUM ON CRYPTATE ION-PAIR ACIDITY
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A thermodynamic analysis was made of the effects of various types of solvation interactions on ion-pair acidity.It was shown that the polarity of the medium does not have an effect on the relative cryptate acidity of organic compounds.
- Antipin, I. S.,Vedernikov, A. N.,Solomonov, B. N.,Konovalov, A. I.
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p. 1861 - 1865
(2007/10/02)
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- CRYPTATE ACIDITY SCALES. V. EQUILIBRIUM ACIDITY OF INDICATOR CH-ACIDS IN TETRAHYDROFURAN
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A scale of equilibrium cryptate acidity in tetrahydrofuran is constructed.Its distinguishing feature is the constancy of the contribution from ionic association.A method is proposed for determination of the constants for the association of the ions into ion pairs in dimethyl sulfoxide.
- Antipin, I. S.,Gareev, R. F.,Vedernikov, A. N.,Konovalov, A. I.
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p. 1039 - 1044
(2007/10/02)
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- Acidities of Glycine Schiff Bases and Alkylation of Their Conjugate Bases
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Equilibrium acidities in Me2SO are reported for six ketimines of the type Ph2C=NCH(R)CO2Et and five aldimines, ArCH=NCH(R)CO2Et.Changing R in the ketimine from H to Ph increased the pKa by 2.2 units.This surprising acidity decrease for Ph substitution points to a substantial increase in steric effect, as do the increases in pKa of 3.8 and 4.2 units observed for the replacement of hydrogen by Me and PhCH2, respectively.Phase-transfer alkylation of the Ph2C=NCH2CO2Et ketimine gave over 90 percent of monoalkylate whereas, under similar conditions, the aldimine 4-ClC6H4CH=NCH2CO2Et gave a mixture of mono- and dialkylate.The difference is that the pKa of the monoalkylated aldimine is essentially the same as that of the parent, which leads to rapid equilibration with the parent anion and consequent dialkylation.The rates of alkylation in Me2SO of these parent and monoalkylated anions did not differ greatly, showing that the relative pKHAs of the parent acid and its monoalkyl derivative, rather tham the relative rates of the mono- and dialkylation reactions, is the principal factor that determines the extent of the competition between monoalkylation and dialkylation.
- O'Donnell, Martin J.,Bennett, William D.,Bruder, Willian A.,Jacobsen, William N.,Knuth, Keith,et al.
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p. 8520 - 8525
(2007/10/02)
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- Thermolyse et photolyse de tetrazolines
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The thermolysis of tetrazolines leads to diaziridines the cyclic carbon atom bears two hydrogens or one hydrogen and a methyl group.If one of the substituents of this carbon is aromatic, two cycloreversions may be observed, giving azides and imines.The photolysis at low temperature leads to diaziridines, except when the cyclic carbon atom bears two insaturated substituents.
- Carboni, B.,Tonnard, F.,Carrie, R.
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p. 525 - 530
(2007/10/02)
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- Aroylation of Carbanions Derived from N-(Diphenylmethyl)arylmethanimines. A Synthesis of 4-Aroyloxy-2-azabuta-1,3-dienes
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The acylation of carbanions derived from N-(diphenylmethyl)arylmethanimines using aroyl chlorides, allows the preparation of a new type of substituted 2-azabuta-1,3-dienes in which the imino group is conjugated with an enol ester.The reaction is quite general and facilitates the preparation of a wide range of 2-azadienes with electron-donating and electron-withdrawing groups on the phenyl rings.The site selectivity for the attack of the electrophile on the aza-allyl anion can be controlled by the substituents on the carbanion and on the hardness of the electrophile.
- Armesto, Diego,Ortiz, Maria J.,Perez-Ossorio, Rafael
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p. 2021 - 2026
(2007/10/02)
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- Stereoselective Synthesis of Monocyclic &β-Lactams from the Reaction of Acid Chlorides/Mixed Anhydrides with Substituted Imines.
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Monocyclic β-lactams (IIa-f, IIIa, d) having the desired stereochemistry can be prepared from appropriate imines (Ia-f) on treatment with acid chlorides or mixed anhydrides in the presence of Et3N.These β-lactams are obtained in appreciable yields and also show some antimicrobial activity.
- Sharma, S. D.,Kaur, S.,Mehra, Usha
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p. 141 - 144
(2007/10/02)
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- A CONVENIENT SYNTHETIC METHOD FOR SCHIFF BASES. THE TRIMETHYLSILYL TRIFLUOROMETHANESULFONATE-CATALYZED REACTION OF N,N-BIS(TRIMETHYLSILYL)AMINES WITH ALDEHYDES AND KETONES
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N,N-Bis(trimethylsilyl)amines react with aldehydes or ketones in the presence of trimethylsilyl trifluoromethanesulfonate to give Schiff bases in high yields.In situ utilization of the reaction solution as the Schiff base is also demonstrated.
- Morimoto, Toshiaki,Sekiya, Minoru
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p. 1371 - 1372
(2007/10/02)
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- FORMATION OF ARYL RADICALS FROM NITROSOARENES BY THE REACTION WITH DIPHENYLMETHYLENEAMINO RADICALS
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By the reaction between nitrosoarenes and diphenylmethyleneamino radicals at 60 - 70 deg C aryl radicals are generated together with nitrogen and benzophenone.
- Suehiro, Tadashi,Masuda, Seiichi,Motoyama, Noboyuki,Sasaki, Masaru
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p. 1329 - 1330
(2007/10/02)
-