- Reactivity of N phenyl iminophosphoranes towards ozone: Evidence of trioxo azaphospholane intermediates
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The ozonation of N-phenyl-iminophosphoranes R3P=NPh 1a-b leads, after the P-N bond breakage, to the corresponding phosphorus oxides 2a-b with the formation of complex adducts 3a-b which precipitate at room temperature. The stoichiometry and the reaction mechanism depend on the nature of substituents R linked to the phosphorus atom. For R=Ph we detected the phosphonium intermediate 5a, whereas for R=OEt the trioxoazaphospholanes 7b-9b were characterized by 31P NMR.
- El Khatib, Fayez,Bellan, Jacques,Koenig, Max
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Read Online
- A new synthetic utility of iminophosphoranes. Synthesis of trifluoromethylated enamino and imino esters
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A new synthetic utility of iminophosphoranes, including the reaction of iminophosphoranes with trifluoroacetic anhydride and organozinc compounds, to afford trifluoromethylated amino and imino esters is described.
- Shen, Yanchang,Gao, Shu
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Read Online
- Metal-free deoxygenation and reductive disilylation of nitroarenes by organosilicon reducing reagents
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A metal-free deoxygenation and reductive disilylation of nitroarenes was achieved using N,N’-bis(trime-thylsilyl)-4,4’-bipyridinylidene (1) under mild and neutral reaction conditions, and a broad functional group tolerance was possible in this reaction. Mono-deoxygenation, giving a synthetically valuable N,O-bis(trimethylsilyl)phe-nylhydroxylamine (7a) as a readily available and safe phenylnitrene source from nitrobenzene, and double-deoxy-genation, giving N,N-bis(trimethylsilyl)anilines 8, were easily controlled by varying the amounts of 1 and reaction temperature as well as adding dibenzothiophene (DBTP). Reaction of 2-arylnitrobenzenes with 1 resulted in the formation of the corresponding carbazoles 14 via in situ-gen-erated phenylnitrene species derived by thermolysis of N,O-bis(trimethylsilyl)phenylhydroxylamines 7, followed by their subsequent intramolecular C H insertion. In addition, the intramolecular N N coupling reaction proceeded in the reduction of 2,2’-dinitrobiphenyl derivatives by 1, giving the corresponding benzo[c]cinnolines.
- Bhattacharjee, Argha,Hosoya, Hiromu,Ikeda, Hideaki,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
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p. 11278 - 11282
(2018/10/20)
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- Preparation of 1,2,5-Trisubstituted 1H-Imidazoles from Ketenimines and Propargylic Amines by Silver-Catalyzed or Iodine-Promoted Electrophilic Cyclization Reaction of Alkynes
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From readily available propargylic amines, 1,2,5-trisubstituted imidazoles are efficiently obtained through a cascade reaction catalyzed by AgOTf or promoted by molecular iodine. The AgOTf-catalyzed reaction involves nucleophilic addition of propargylic amine to ketenimine, a silver-catalyzed electrophilic cyclization reaction of alkyne, and a tautomerism/isomerism/metal-H exchange cascade. The iodine-mediated counterpart yields 5-formyl-1,2-disubtituted imidazoles, which presumably includes a cascade hydrolysis/oxidation reaction. Furthermore, the presented protocol can be scaled up and the resultant 1,2,5-trisubstituted imidazole can be converted into fused indeno[1,2-d]imidazole. 1,2,5-Trisubstituted imidazoles are efficiently prepared from readily available propargylic amines through a AgOTf-catalyzed or molecular iodine-promoted cascade reaction. The presented protocol can be scaled up and the resultant 1,2,5-trisubstituted imidazoles can be converted into fused indeno[1,2-d]imidazoles.
- Zhou, Xiaorong,Jiang, Zheng,Xue, Lexing,Lu, Ping,Wang, Yanguang
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supporting information
p. 5789 - 5797
(2015/09/15)
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- Synthesis of 4-fluoromethylsydnones and their participation in alkyne cycloaddition reactions
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We report the synthesis and some structural studies of 4-trifluoromethyl, 4-difluoromethyl-, and 4-monofluoromethylsydnones. All but the latter compounds are stable and represent effective precursors to a range of pyrazoles after cycloaddition reactions with alkynes. The cycloadditions are generally highly regioselective and provide 5-fluoromethylpyrazole products, although we have observed that Bn-substituted sydnones can provide an unexpected alkyne insertion mode that generates the 3-fluoromethyl isomer.
- Foster, Robert S.,Adams, Harry,Jakobi, Harald,Harrity, Joseph P. A.
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p. 4049 - 4064
(2013/06/05)
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- Kinetics and mechanism of the nitrosobenzene deoxygenation by trivalent phosphorous compounds
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The reaction of aryl nitroso compounds with organic phosphines and phosphites in aerated media is a convenient non-photolytic procedure to generate aromatic nitroso oxides. The reaction rate constants and activation parameters of the key (for the proposed method of nitroso oxide generation) reaction of nitrosobenzene with tripenyl phosphite or para-substituted phosphines (4-RC 6H4)3P (R = MeO, Me, H, F), as well as that of para-methoxynitrosobenzene with triphenylphosphine in acetonitrile were determined by kinetic spectrophotometry and chemiluminescence. A significant transfer of the electron density to the nitroso compound occurs in the transition state of the reaction as was revealed using the Hammett correlation analysis and DFT calculations in the M06L/6-311+G(d,p) approximation. The introduction of the electron-donor substituent MeO into the para-position of PhNO decreases the reactivity of the nitroso compound by two orders of magnitude. The reactivity of triphenyl phosphite in the oxygen atom transfer reaction is lower by two orders of magnitude compared to that of triphenylphosphine. In the case of the reactions of PhNO with phosphines, the apparent rate constant depends on the oxygen content in the reaction medium.
- Khursan,Shamukaev,Chainikova,Khursan,Safiullin
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p. 2477 - 2486
(2014/11/08)
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- Phosphinimine-borane combinations in frustrated Lewis pair chemistry
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The phosphinimines Ph3PNR (R = Ph 1, C6F 52, tBu 3) are combined with B(C6F5) 3 in an effort to explore the frustrated Lewis pair (FLP) chemistry. While compound 1 is shown to form an adduc
- Jiang, Chunfang,Stephan, Douglas W.
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p. 630 - 637
(2013/02/23)
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- A general and regioselective synthesis of 5-trifluoromethyl-pyrazoles
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Two synthetic approaches to 4-trifluoromethylsydnones, a novel class of these mesoionic reagents, are reported. These compounds undergo regioselective alkyne cycloaddition reactions, thereby providing a general approach to 5-trifluoromethylpyrazoles. This method has been employed in a short formal synthesis of the herbicide fluazolate.
- Foster, Robert S.,Harrity, Joseph P. A.,Jakobi, Harald
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supporting information
p. 4858 - 4861,4
(2012/12/12)
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- Reaction between triphenylphosphine and aromatic amines in the presence of diethyl azodicarboxylate: An efficient synthesis of aryliminophosphoranes under neutral and mild conditions
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An efficient synthesis of aryliminophosphoranes is described. A mixture of an aromatic amine, diethyl azodicarboxylate and triphenylphosphine undergo a Mitsonobu type reaction at ambient temperature in dry dichloromethane to afford aryliminophosphoranes in excellent yields.
- Adib, Mehdi,Sheikhi, Ehsan,Deljoush, Azadeh
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experimental part
p. 4137 - 4140
(2011/06/24)
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- Synthetic and mechanistic studies of the aza-retro-claisen rearrangement. a facile route to medium ring nitrogen heterocycles
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An efficient synthesis of medium-sized heterocyclic rings was achieved using a one-pot aza-Wittig/retro-aza-Claisen sequence of vinyl cyclobutanecarboxaldehydes derived from simple allylic carbonates. The use of various Staudinger reagents in the aza-Wittig reaction allows for a variety of N-substituted products to be obtained. The rearrangement is under thermodynamic control driven by relief of the cyclobutane ring strain and resonance stabilization of the resulting vinylogous amide/sulfonamide.
- Boeckman Jr., Robert K.,Genung, Nathan E.,Chen, Ke,Ryder, Todd R.
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supporting information; experimental part
p. 1628 - 1631
(2010/06/19)
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- Copper(II) acetate/oxygen-mediated nucleophilic addition and intramolecular C-H activation/C-N or C-C bond formation: One-pot synthesis of benzimidazoles or quinazolines
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Diarylcarbodiimides or benzylphenylcarbodiimides are converted to 1,2-disubstituted benzimidazoles or 1,2-disustituted quinazolines via addition/intramolecular C-H bond activation/C-N or C-C bond forming reaction using copper(II) acetate/oxygen [Cu(OAc)2/O2] as the oxidant at 100°C in one-pot cascade procedure. Copyright
- He, Hua-Feng,Wang, Zhi-Jing,Bao, Weiliang
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supporting information; experimental part
p. 2905 - 2912
(2010/12/29)
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- Selective synthesis of 4-alkylidene-β-lactams and N,N′- diarylamidines from azides and aryloxyacetyl chlorides via a ketenimine-participating one-pot cascade process
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(Chemical Equation Presented) A one-pot cascade approach to 4-alkylidene-β-lactams and N,N-diarylamidines from aryl azides and aryloxyacetyl chlorides has been developed. The chemical outcome of the reaction can be controlled selectively by an appropriate choice of the stoichiometric ratio of different substrates and reagents. The products should find use in pharmaceutical discovery, especially in the development of new antimicrobial agents against multidrug-resistant pathogens.
- Yang, Yun-Yun,Shou, Wang-Ge,Hong, Deng,Wang, Yan-Guang
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p. 3574 - 3577
(2008/09/20)
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- The preparation of 1,2,3-trisubstituted guanidines
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An operationally straightforward and efficient benzotriazole-based method for the guanylation of diverse amines by use of the new reagent classes (bis-benzotriazol-1-yl-methylene)amines 13a-13f and benzotriazole-1- carboxamidines 17a-17i is described. The preparation is described for a variety of both acyclic and cyclic 1,2,3-trisubstituted guanidines in high yields.
- Katritzky, Alan R.,Khashab, Niveen M.,Bobrov, Sergey
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p. 1664 - 1675
(2007/10/03)
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- Vinyltriphenylphosphonium salt mediated serendipitous synthesis of aryliminophosphoranes
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Crystalline phosphorus ylides are obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dimethyl acetylenedicarboxylate and aromatic amines, such as aniline, 1-naphthylamine, p-toluidine, 4-bromoaniline, 4-nitroaniline, 4-acetylaniline, 2-aminopyridine, or 2-amino-5-bromopyridine. These stabilized phosphoranes undergo a smooth intramolecular reaction in boiling p-xylene or toluene to produce aryliminophosphoranes in excellent yields.
- Yavari, Issa,Adib, Mehdi,Hojabri, Leila
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p. 7213 - 7219
(2007/10/03)
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- Innovative synthesis of 4-carbaldehydepyrrolin-2-ones by zwitterionic rhodium catalyzed chemo- and regioselective tandem cyclohydrocarbonylation/CO insertion of α-imino alkynes
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The tandem cyclohydrocarbonylative/CO insertion of α-imino alkynes employs CO, H2, and catalytic quantities of zwitterionic rhodium complex (η6-C6H5 BPh3)-Rh+(1,5-COD) and triphenyl phosphite affording aldehyde substituted pyrrolinones in 67-82% yields. This unique transformation is readily applied to imino alkynes containing alkyl, alkoxyl, vinyl, and aryl substituents. The ability to prepare highly functionalized pyrrolinones makes this an attractive route to these important and versatile pharmaceuticals.
- Van den Hoven,Alper
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p. 10214 - 10220
(2007/10/03)
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- Acyclic amides as estrogen receptor ligands: Synthesis, binding, activity and receptor interaction
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We have prepared a series of bisphenolic amides that mimic bibenzyl and homobibenzyl motifs commonly found as substructures in ligands for the estrogen receptor (ER). Representative members were prepared from three classes: N-phenyl benzamides, N-phenyl acetamides, and N-benzyl benzamides; in some cases the corresponding thiocarboxamides and sulfonamides were also prepared. Of these three classes, the N-phenyl benzamides had the highest affinity for ER, the N-phenyl acetamides had lower, and the N-benzyl benzamides were prone to fragmentation via a quinone methide intermediate. In the N-phenyl benzamide series, the highest affinity analogues had bulky N-substituents; a CF3 group, in particular, conferred high affinity. The thiocarboxamides bound better than the corresponding carboxamides and these bound better than the corresponding sulfonamides. Binding affinity comparisons suggest that the p-hydroxy group on the benzoate ring, which contributes most to the binding, is playing the role of the phenolic hydroxyl of estradiol. Computational studies and NMR and X-ray crystallographic analysis indicate that the two anilide systems studied have a strong preference for the s-cis or exo amide conformation, which places the two aromatic rings in a syn orientation. We used this structural template, together with the X-ray structure of the ER ligand binding domain, to elaborate an additional hydrogen bonding site on a benzamide system that elevated receptor binding further. When assayed on the individual ER subtypes, ERα and ERβ, these compounds show modest binding affinity preference for ERα. In a reporter gene transfection assay of transcriptional activity, the amides generally have full to nearly full agonist character on ERα, but have moderate to full antagonist character on ERβ. One high affinity carboxamide is 500-fold more potent as an agonist on ERα than on ERβ. This work illustrates that ER ligands having simple amide core structures can be readily prepared, but that high affinity binding requires an appropriate distribution of bulk, polarity, and functionality. The strong conformational preference of the core anilide function in all of these ligands defines a rather rigid geometry for further structural and functional expansion of these series. Copyright (C) 2000 Elsevier Science Ltd.
- Stauffer, Shaun R.,Sun, Jun,Katzenellenbogen, Benita S.,Katzenellenbogen, John A.
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p. 1293 - 1316
(2007/10/03)
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- A one-pot aza-Wittig based solution and polymer supported route to amines
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This paper presents a high yielding one-pot solution phase and polymer supported synthesis of a range of primary and secondary amines starting from azides and aldehydes. The synthesis utilises a tandem process which begins with an aza-Wittig reaction between the aldehyde and an iminophosphorane, followed by reduction, or organometallic 1,2-addition reaction, of the resultant imine. The requisite iminophosphoranes were accessed using the highly efficient Staudinger reaction between the azide starting material and a phosphine. The process was applicable to the solid phase by the use of polymer supported iminophosphoranes and polymer supported cyanoborohydride.
- Hemming,Bevan,Loukou,Patel,Renaudeau
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p. 1565 - 1568
(2007/10/03)
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- Complexes of N-aryltriphenylphosphinimines with mercury(II) halides
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The synthesis IR and 31P NMR spectra of the complexes of various N-aryltriphenylphosphinimines with some mercury dihalides as well as the corresponding phosphonium salts are reported It is shown by an X-ray crystal structure analysis of the complex of the unsubstituted phosphinimine with HgCl2 that in the solid state these complexes form dimers via two Hg...μ2 Cl...Hg bridges.
- Braun, Thomas P.,Gutsch, Paul A.,Zimmer, Hans
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p. 858 - 862
(2007/10/03)
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- REACTIVITY OF IMINOPHOSPHORANES TOWARDS SOME SYMMETRICAL DICARBONYL DICHLORIDES : SYNTHESES AND MECHANISMS
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In situ generated iminophosphoranes 1 react with dicarbonyl dihalides 2a-b and 3a-c to give known or new nitrogen heterocycles.The proposed mechanisms involve elimination of either triphenyl-phosphine oxide or dichlorotriphenylphosphorane depending upon both the iminophosphorane and the dicarbonyl compound.
- Aubert, Thierry,Farnier, Michel,Guilard, Roger
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- N-Phenyl-P,P,P-triarylphospha-λ5-azenes, Triarylphosphines, and Triarylphosphine Oxides. Substituent Effects on 15N, 31P, and 13C NMR Spectra
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The syntheses and 15N, 31P, and 13C NMR spectra of a series of N-phenyl-P,P,P-triarylphospha-λ5-azenes 4 and the 31P and 13C NMR spectra of the corresponding series of triarylphosphines 5 and triarylphosphine oxides 6 are reported.The substituent effects on the chemical shifts can be best accommodated and rationalized by use of a model for system 4 whereby the dipole of the aryl group and its pendant R group polarizes the rest of the molecule.This includes the P and N atoms and phenyl ring, where an electron-withdrawing R group increases the electron density of the P, N, and ipso C-1 while decreasing the electron density on C-3 and C-4 of the N-phenyl ring (Figure 3).A similar polarization pattern for the phosphine oxide series 6 is suggested.In the phosphine series 5, the chemical shift data is consistent with the lone electron pair on the phosphorus atom delocalizing into the aryl rings.The coupling constant data, in particular 1JPN for series 4 and 1JPC for series 4-6, were examined with use of the Hammett monosubstituent parameter (MSP) and the Taft dual-substituent parameter (DSP) approaches.For systems 4 and 6, without a lone electron pair on the phosphorus atom, a better electron-donating substituent increases the one-bond P-C(Ar) coupling constant.On the contrary, in the phosphine series 5, where there is a lone electron pair on the phosphorus, a better electron-withdrawing substituent increases the one-bond P-C(Ar) coupling constant.DSP treatment of 1JPC, and comparing to the few related systems in the literature,shows three types of systems.One, which includes 4 and 6, has an atom, phosphorus in these cases, that does not have a lone pair of electrons attached to the ring to which is attached an atom with a lone pair of electrons.Here, the resonance effect on 1JPC predominates.A second series, which includes phosphines 5, has a lone pair on the atom attached to the aryl ring.In these cases, the resonance effect is ca. 50percent greater than the inductive effect.Finally, the third series, exemplified by two examples from the literature, has a tetrahedral atom (without a lone pair) attached to the aryl ring and this in turn is attached to tetrahedral atoms without lone electron pairs.In these case, the resonance and inductive effects are fairly comparable.
- Chou, Whe-Narn,Pomerantz, Martin
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p. 2762 - 2769
(2007/10/02)
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- Nouvelle voie de synthese d'isoidindolones et d'isoquinoleines par condensation d'iminophosphoranes avec l'ortho-phthalaldehyde: reactions, mecanismes et etude structurale
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The condensation of various iminophosphoranes with o-phthalaldehyde led directly to N-substituted isoindoline-1-ones and 3-acylisoquinolines.Three different mechanisms, depending on the nature of the iminophosphorane and reaction conditions, are proposed.All the compounds have been fully characterized, particularly by one- and two-dimensional nuclear magnetic resonance spectroscopy.
- Aubert, Thierry,Farnier, Michel,Guilard, Roger
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p. 842 - 851
(2007/10/02)
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- A One-Pot Synthesis of 2-Substituted 2,4,5,6-Tetrahydrocyclopentapyrazoles
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The 2-substituted 2,4,5,6-tetrahydrocyclopentapyrazoles 3 were selectively synthesized by condensation of various in situ generated iminophosphoranes with the 2-azido-1-cyclopentene-1-carboxaldehyde (2).
- Aubert, Thierry,Tabyaoui, Badia,Farnier, Michel,Guilard, Roger
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p. 742 - 743
(2007/10/02)
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- PHOSPHORORGANISCHE VERBINDUNGEN 89 Quartaere Phosphoniumsalze mit Heteroatomen am Phosphor Herstellung, Eigenschaften und Elektroreduktive Spaltung
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The half-potential of 35 quaternary phosphonium salts with one or more hetero-atoms attached to phosphorus are reported, and the fission products determined for the electroreduction of nine phosphonium salts.The influence of the ligands attached to phosphorus by hetero-atoms on both the half-wave potential and the course of the fission reaction is discussed.The order of precedence in the cleavage of the ligands at phosphorus is examined to determine whether a meaningful, qualitative order of stability for the corresponding ligands as free radicals can be deduced.
- Horner, Leopold,Jordan, Manfred
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p. 209 - 214
(2007/10/02)
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