Phenyl Ketene Research Articles

Reaction of (chloro carbonyl) phenyl ketene with 5-amino pyrazolones: Synthesis, characterization and theoretical studies of 7-hydroxy-6-phenyl-3-(phenyldiazenyl)pyrazolo[1,5-a]pyrimidine-2,5(1H,4H)-dione derivatives

New 7-hydroxy-6-phenyl-3-(phenyldiazenyl)pyrazolo[1,5-a]pyrimidine-2,5(1H,4H)-dione derivatives were synthesized from the reaction of (chlorocarbonyl)phenyl ketene and 5-amino pyrazolones in high to excellent yields and short reaction times. Structures of the new compounds were fully characterized by their spectral data IR, 1H NMR, and 13C NMR and by the theoretical results. Density Functional Theory (DFT) was used to optimize the structures, compute the energies and vibrational frequencies IR and 1H NMR shielding tensors of the desired products. The theoretical results excellent are compared with the experimental data.

ChemInform Abstract: Generation of Reactive Ketenes under Flow Conditions Through Zinc‐Mediated Dehalogenation.

Herein, we describe the generation of highly reactive monoalkyl and phenyl ketenes by using a dehalogenation procedure under flow conditions. All ketenes were generated in good yields (determined by quenching with an appropriate aniline derivative) and showed high reactivity in the [2+2] cycloaddition with imines, resulting in the formation of a range of β-lactams at room temperature in less than 10 minutes. Furthermore, initial experiments were performed by using these reactive ketenes for the synthesis of β-lactams under flow conditions.

Generation of Reactive Ketenes under Flow Conditions through Zinc-Mediated Dehalogenation

Herein, we describe the generation of highly reactive monoalkyl and phenyl ketenes by using a dehalogenation procedure under flow conditions. All ketenes were generated in good yields (determined by quenching with an appropriate aniline derivative) and showed high reactivity in the [2+2] cycloaddition with imines, resulting in the formation of a range of β-lactams at room temperature in less than 10 minutes. Furthermore, initial experiments were performed by using these reactive ketenes for the synthesis of β-lactams under flow conditions.

ChemInform Abstract: Structures and Ambident Reactivities of Azolium Enolates.

Oxygen versus carbon: Azolium enolates were generated by the reactions of N-heterocyclic carbenes (NHCs) with methyl phenyl ketene and characterized by X-ray crystallography. Kinetic studies show that the enolate oxygen is 20 times more nucleophilic than the carbon atom, but under thermodynamic control exclusive C-addition products were formed.

Tandem Processes in C‐Aryl Ketenes and Ketenimines Triggered by [1,5]‐Hydride‐Like Migration of an Acetalic Hydrogen Atom

AbstractHeating a range of suitably substituted diazoacetoacetates produced a family of 2‐(1,3‐dioxolan‐2‐yl)phenyl ketenes that, under thermal conditions, smoothly underwent a [1,5]‐H shift/6π‐electrocyclic ring‐closure sequence to give 1H‐2‐benzopyrans. The application of such processes to ketenes, produced by replacing the phenyl scaffolding with a thiophene ring, afforded thienopyrans. The aza‐Wittig reaction of these 2‐(1,3‐dioxolan‐2‐yl)phenyl and thienyl ketenes with N‐aryliminophosphoranes provided analogous ketenimines that transform into the respective 1(2H)isoquinolinones and thienopyridinones under similar thermal conditions, following the same type of cascade sequence.

Structures and Ambident Reactivities of Azolium Enolates

Oxygen versus carbon: Azolium enolates were generated by the reactions of N-heterocyclic carbenes (NHCs) with methyl phenyl ketene and characterized by X-ray crystallography. Kinetic studies show that the enolate oxygen is 20 times more nucleophilic than the carbon atom, but under thermodynamic control exclusive C-addition products were formed.

A one-pot reaction of (chlorocarbonyl) phenyl ketene with β-ketoamides and thiochromen-2-one

Readily available (chlorocarbonyl)phenyl ketene and a varied set of β-ketoamides were reacted in a one-step procedure to produce 2-pyrone derivatives. β-Ketoamide derivatives are versatile intermediates for the synthesis of heterocyclic compounds. For instance, 1-morpholino-3-phenyl-1,3-propanedione, 1-phenyl-3-piperidino-1,3-propanedione, 1-phenyl-3-pyrrolidino-1,3-propanedione, 1-piperidino-1,3-butanedione, 1-morpholino-2-phenyl ethanone were used in these reactions to produce 2-pyrone derivatives. In addition, the preparation of 4-hydroxy-3-phenylthiochromeno[4,3-b]pyran-2,5-dione derivatives and 4-hydroxy-7-methyl-3-phenyl pyrano[3,2-c]chromeno-2,5-dione were described. For the synthesis of these compounds 4-hydroxy-2H-thiochromen-2-ones and 4-hydroxy-8-methyl-2H-chromen-2-one were reacted with (chlorocarbonyl)phenyl ketene and the final products were isolated in good yields.

Synthesis of Isoxazolone Derivatives from (Chlorocarbonyl)phenyl Ketene with Benzhydroxamic Acids

The reaction of (chlorocarbonyl)phenyl ketene, with readily available benzhydroxamic acid derivatives, such as benzhydroxamic acid, 4-chlorobenzhydroxamic acid, 3-nitrobenzhydroxamic acid, 4-methylbenzhydroxamic acid, N-hydroxy-3-oxo-3-phenylpropionamide, N-hydroxy-2-phenylacetamide, affords isoxazolone derivatives in high yields in a one step procedure. The formation of the products proceeds by a mechanism, that involves replacement of chlorine of the ketene, by benzhydroxamic acids, followed by rapid ring closure of this intermediate to form isoxazolone derivatives.

Synthesis of gradient polymer by using polysiloxane‐based photoinitiator

This paper reported a polysiloxane‐based photoinitiator (184‐AC‐Si), which was synthesized basing on traditional photoinitiator 1‐hydroxy‐cyclohexyl phenyl ketene (184) and polysiloxane. Its structure was confirmed by Hydrogen‐1 nuclear magnetic resonance (1H NMR), real‐time infrared spectroscopy and gel permeation chromatography (GPC). Ultraviolet (UV) absorption spectra of 184‐AC‐Si showed a red‐shifted maximum absorption compared with 184. The kinetics of photopolymerization was studied by real‐time infrared spectroscopy. More importantly, because of the polysiloxane‐based photoinitiator had good ability to float up, which could be proved by X‐ray photoelectron spectroscopy, mapping energy dispersive spectroscopy, UV absorption, and GPC measurements, a convenient and simple method for preparing gradient polymer initiated by 184‐AC‐Si was successfully developed. Copyright © 2011 John Wiley & Sons, Ltd.

ChemInform Abstract: Studies on Condensation of Chlorocarbonyl Phenyl Ketene with N‐Unsubstituted Amides: Synthesis of Some New 1,3‐Oxazin‐6‐ones.

A series of 1,3-oxazin-6-one derivatives has been synthesized upon treatment of N-unsubstituted amides with chlorocarbonyl phenyl ketene under reflux in toluene for several minutes. In this simple way, 2,5-disubstituted derivatives of 1,3-oxazin-6-ones have been obtained in high yields.

Rhodium-Catalyzed Linear Codimerization and Cycloaddition of Ketenes with Alkynes

A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes with internal alkynes have been developed. These reactions proceed smoothly with the same rhodium catalyst, RhCl(PPh3)3, and are highly dependent on the structure and reactivity of the starting ketenes.

ROTATIONAL BARRIERS AND VIBRATIONAL SPECTRA OF PHENYL KETENE, AZIDE, AND ISOCYANATE

Our interest in conjugation effects in substituted phenyl compounds has turned our attention to the highly reactive compounds phenyl ketene, azide, and isocyanate, which due to their reactivity are of utmost importance in organic synthesis. We performed local density functional theory (DFT) calculations using a 6-311G** basis set to calculate the structures and potential functions of the internal rotation. Further for the minimum structures we computed the vibrational infrared and Raman spectra of the three molecules. In order to confirm that DFT works rather well in these systems we performed the geometry optimizations also using ab initio Moeller–Plesset perturbation theory of second order (MP2) in the same basis set. As expected there exist just two minimum structures for each of the molecules which both correspond to planar structures and are identical due to the symmetry of the phenyl ring. The transitions states (TS) of the internal rotations are the perpendicular ones. We expect conjugation to play no major role in these molecules since extensive conjugation effects would imply a large reduction of the aromatic character of the phenyl ring which in turn would greatly destabilize the systems. However, although the rotational barriers appear to be rather small in these systems conjugation must play at least some role in stabilizing the planar ground state. As detailed later, the relative heights of the rotational barriers can all be explained naturally. Experimental vibrational spectra could be obtained only for phenyl isocyanate and azide, but not for the ketene because of the high reactivity of this molecule. Since in the former cases the calculated spectra agree fairly well with the measured ones, we present those of the other molecule as theoretical prediction, which could be useful to detect spectroscopically in a reaction mixture residual reactant. On the basis of potential energy distribution (PED) calculations we present a complete assignment of the vibrational lines to symmetry coordinates, where, for example, ring breathing must show up with rather large intensities in the Raman spectra of the molecules.

The Condensation of (Chlorocarbonyl)phenyl Ketene with Bisnucleophiles. Synthesis of 4-Hydroxy-5-phenylpyro-[2,3-c]pyrazol-6-ones and Formation of Pyrazolo[1,2-a]pyrazole-triones by Hydrogen Exchange in Unstable Mesoionic Compounds

The addition of (chlorocarbonyl)phenyl ketene 2 to 5-alkylpyrazol-3(4H)-ones 1 led to the formation of 3-hydroxypyrazolo[1,2-a]pyrazole-dione/pyrazolo[1,2-a]pyrazole-trione derivatives 3. This is ascribed to hydrogen exchange in initially formed unstable, mesoionic pyrazolo[1,2-a]pyrazol-4-ium-5-olates. In contrast, condensation of the same ketene with 3-alkyl-1-phenyl-2-pyrazolin-5-ones 4 afforded 4-hydroxy-3-alkyl-1,5-diphenylpyrano[2,3-c]pyrazol-6-one derivatives 5. The latter reaction provides a new and rapid route to 4-hydroxy-2-pyrones fused to pyrazole rings, in good to excellent yields.

ChemInform Abstract: The Reaction of (Chlorocarbonyl)phenyl Ketene with Enaminones: A Novel Synthesis of Some 5‐Acyl‐4‐hydroxy‐2‐(1H)‐pyridinones and 7‐Hydroxy‐5‐oxo‐1,4‐diazepin Derivative.

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One-Pot Synthesis of 4-Hydroxy-3-phenyl-2H-pyrano[3,2-b]benzofuran-2-one Derivatives

Novel 4-hydroxy-3-phenyl-2H-pyrano[3,2-b]benzofuran-2-ones (15a–d), were synthesized in a one-step procedure by the reaction of substituted benzofuran-3-ones 12a–d and (chlorocarbonyl)phenyl ketene.

The reaction of (chlorocarbonyl)phenyl ketene with enaminones: A novel synthesis of some 5‐acyl‐4‐hydroxy‐2‐(1H)‐pyridinones and 7‐hydroxy‐5‐oxo‐1,4‐diazepin derivative

Abstract magnified imageA series of substituted 5‐acyl‐4‐hydroxy‐2‐(1H)‐pyridinone derivatives has been prepared in a one‐step procedure from condensation of (chlorocarbonyl)phenyl ketene with some enaminones which were prepared from 1,3‐diketones, such as 2,4‐pentanedione, 1‐phenyl‐1,3‐butanedione, and ethyl acetoacetate in boiling toluene as a solvent. A mechanism is presented to account for the formation of the products. The overall sequence provides a simple and efficient route to prepare 3,4,5,6‐tetrasubstituted 2‐(1H)‐pyridinone in good to excellent yields and in a short experimental time. J. Heterocyclic Chem., (2009).

Studies on condensation of chlorocarbonyl phenyl ketene with N-unsubstituted amides: synthesis of some new 1,3-oxazin-6-ones

A series of 1,3-oxazin-6-one derivatives has been synthesized upon treatment of N-unsubstituted amides with chlorocarbonyl phenyl ketene under reflux in toluene for several minutes. In this simple way, 2,5-disubstituted derivatives of 1,3-oxazin-6-ones have been obtained in high yields.

Synthesis and spectral studies of pyranone derivative and its Cu(II), Co(II), Ni(II) and Zn(II) complexes

Under the thermolysis condition, 5-phenyl-2,3-dihydro-2,3-furandione (IV) in inert aprotic solvents as p-xylene at 130–140°C yields 3-benzoyl-4-hydroxy-6-phenyl-2H-pyran-2-one (VI) via phenyl ketene (V). The compound (VI) was converted into the corresponding 3-benzoyl-4-hydroxy-6-phenylpyridin-2(1H)-one (VII), and 3-benzoyl-2-oxo-6-phenyl-2H-pyran-4-yl acetate (VIII), by its reactions with ammonium hydroxyde, and acetic anhydride, respectively. On the other hand, a series of new various metal complexes (IX-XIa, XIb) of VI was synthesized. The results suggest that the compound VI as bidentate ligand indicate a binuclear structure for the Cu(II) complex with square-planar geometry. The Ni(II) and Zn(II) complexes are of tetrahedral and the Co(II) complex is also octahedral geometry with water molecules at the axial positions. The structures of compounds and complexes were characterized on the basis of elemental analysis, Mass, IR, 1H, and 13C NMR spectra.

The condensation of (chlorocarbonyl)phenyl ketene with 1,3-dinucleophiles. I. Synthesis of 4-hydroxy-2-(1H)-pyridinones and mesoionic 1,3-oxazinium olates

Investigation of the reaction of (chlorocarbonyl)phenyl ketene with 1,3-dinucleophiles such as Schiff bases which were prepared from acetophenone and aryl amides led to the discovery of new synthetic pathways towards 4-hydroxy-3,6-disubstituted-2(1H)–pyridinones and 2,5-diaryl6-oxo-5-phenyl-6H-1,3-oxazin-3-ium-4-olates respectively. These reactions provide a new route to produce 2-pyridinones and cross - conjugated heterocyclic mesomeric betaines in good to excellent yields in a short reaction time.

Reactivity of Molybdenum and Rhenium Hydroxo Complexes toward Organic Electrophiles: Reactions that Afford Carboxylato Products

The reactions of the hydroxo complexes [Mo(OH)(η3-methallyl)(CO)2(phen)] (1) and [Re(OH)(CO)3(Me2-bipy)] (2) (phen = 1,10-phenanthroline, Me2-bipy= 4,4‘-dimethyl-2,2‘-bipyridine) with maleic anhydride, phenyl(ethyl)ketene, diphenylketene, and rac-lactide afford new carboxylato complexes. The molybdenum and rhenium hydroxo complexes react in the same way, and their reactions are quantitative. The products, some of which have been characterized by X-ray diffraction, feature monodentate O-bonded carboxylato ligands, and their treatment with triflic acid yields the triflato complexes [Mo(OTf)(η3-methallyl)(CO)2(phen)] and [Re(OTf)(CO)3(Me2-bipy)] and the corresponding free carboxylic acid.