ChemInform Abstract: Formation and X-Ray Structure of a Novel (1IND + 4MP - C4H8O3) Trispiro Adduct from Cyclohept(b)indoles and Methyl Propiolate.

ChemInform ◽  
2010 ◽  
Vol 24 (7) ◽  
pp. no-no
Author(s):  
M. C. K. CHOI ◽  
D. T. W. CHAN ◽  
R. M. LETCHER ◽  
K.-K. CHEUNG
Keyword(s):  
X Ray ◽  
Methyl Propiolate

Synthesis, Structure, and Properties of Homoleptic 1-Oxa-1,3-diene Molybdenum and Tungsten Complexes

1995 ◽  
Vol 50 (3) ◽  
pp. 315-325 ◽  
Author(s):  
Thomas Schmidt ◽  
Stephan Neis ◽  
Richard Goddard
Keyword(s):  
Significant Contribution ◽  
High Yield ◽  
Structure And Properties ◽  
Reaction Conditions ◽  
X Ray ◽  
Unsaturated Ketones ◽  
Methyl Propiolate ◽  
Tungsten Complexes ◽  
Bonding Mode ◽  
And Tungsten

Homoleptic tris(1-oxa-1,3-diene)molybdenum and tungsten complexes are formed as yellow, crystalline compounds in 54-80% isolated yield on treatment of the corresponding β-unsubstituted a,β-unsaturated ketones with W(CO)3(CH3CH2CN)3 or (η6-C6H6)Mo(CO)3 in refluxing hexane. Reaction of these oxadienes with (η6-C6H5CH3)2Mo in tetrahydrofuran or n-hexane provides a new high yield route to homoleptic molybdenum complexes that are otherwise difficult to prepare. X-ray crystal structure analyses of two air-stable, isomeric tungsten complexes reveal a significant contribution of a σ2,η2-bonding mode in the coordinated oxadiene moieties. Under reaction conditions that allow the platinum catalyzed hydrogenation of phenyl substituents in these ligands, the coordinated oxadiene fragments are inert, thus demonstrating an unprecedented chemoselectivity in the hydrogenation of arylsubstituted enones. On the other hand, the complexes are labile enough to catalyze the cyclotrimerization of alkynes such as methyl propiolate.

An Efficient One-Step Synthesis of Dihydroquinoline and Its Application as a Fluorescence Sensor for Selective Detection of Copper (II)

Synthesis ◽  
2018 ◽  
Vol 50 (19) ◽  
pp. 3886-3890 ◽  
Author(s):  
Anawat Ajavakom ◽  
Kamrul Hassan ◽  
Lamduan Jonsai ◽  
Pawitporn Sittapairoj ◽  
Vachiraporn Ajavakom ◽  
...  
Keyword(s):  
Detection Limit ◽  
Fluorescence Quenching ◽  
Addition Reaction ◽  
Selective Detection ◽  
Michael Addition Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Methyl Propiolate ◽  
Amino Phenol ◽  
One Step

An efficient one-step synthetic pathway to dihydroquinoline (DHQ) and benzodihydroquinoline (BDHQ) derivatives involving 1,2-Michael addition reaction between amino phenol/naphthol and two molecules of methyl propiolate followed by intramolecular cyclization and aromatization using cuprous iodide as a catalyst was successfully developed. The synthesized DHQ derivatives displayed highly selective fluorescence quenching in the presence of copper(II) with a very low detection limit (LOD for DHQ is 0.20 μM). Moreover, the mechanisms of both formation of the corresponding DHQ and the fluorescence quenching by copper(II) are proposed along with the evidence of X-ray diffraction data.

Methyleneketenes and methylenecarbenes. XVI. The formation of Diphenylfuran-2-ones and 3-Phenylphthalide as minor products of the pyrolysis of diphenylmethyl propiolate

1981 ◽  
Vol 34 (7) ◽  
pp. 1467 ◽  
Author(s):  
RFC Brown ◽  
FW Eastwood ◽  
N Chaichit ◽  
BM Gatehouse ◽  
JM Pfeiffer ◽  
...  
Keyword(s):  
Structure Determination ◽  
Phenyl Ring ◽  
Diels Alder ◽  
Insertion Reaction ◽  
X Ray ◽  
Flash Vacuum Pyrolysis ◽  
Methyl Propiolate ◽  
Vacuum Pyrolysis ◽  
Labelling Experiment ◽  
A Minor

The formation of a mixture of lactones as a minor product of the flash vacuum pyrolysis of diphenyl-methyl propiolate (1) has been investigated further. ��� The diphenylfuran-2-ones (3), (4), and (5) are shown to be formed through an intramolecular insertion reaction of the methylenecarbene (2), formed from (1) at 640°, which leads to 5,5-diphenyl-furan-2(5H)- one (3) as the primary product. ��� 3-Phenylphthalide (8) is apparently formed by intramolecular Diels-Alder addition of the C≡C bond of (1) to one phenyl ring which acts as the diene component, followed by loss of acetylene from an intermediate barrelene derivative (10). This is confirmed by a deuterium labelling experiment. ��� 1-Phenyl-2-benzoxepin-3(1H)-one (7), considered at first as a possible intermediate in the pyrolysis of (1), is synthesized in six steps from 2-aminobenzophenone, and its X-ray structure determination is reported. On pyrolysis at 640°/0.07 mm (7) decarbonylates smoothly to give 2-vinylbenzophenone.

Metallkomplexe mit biologisch wichtigen Liganden, CXXI [1]. Orthopalladierte Enolate aus N-(Diphenylmethylen)-Schiff-Basen von a-Aminosäureestern als ambivalente 1,3-Dipole in [2+3]-Cycloadditionsreaktionen. Strukturen einer Reihe von Cycloaddukten

1999 ◽  
Vol 54 (8) ◽  
pp. 970-988 ◽  
Author(s):  
Bernhard Schreiner ◽  
Reinhold Urban ◽  
Anastassios Zografidis ◽  
Karlheinz Sünkel ◽  
Kurt Polborn ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Fumaric Acid ◽  
Methyl Acrylate ◽  
Methyl Esters ◽  
Acid Form ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Methyl Propiolate ◽  
Dimethyl Acetylene Dicarboxylate

Enolates of ortho-palladated N-(diphenylmethylene) Schiff bases from glycine esters (R3P)Pd[(C6H4)(C6H5)C=N-C(R')=CO2R] were isolated and have been shown to be ambivalent 1,3-dipoles in [2+3] cycloadditions. Tetracyanoethene, dimethyl acetylene dicarboxylate, dimethyl azodicarboxylate, thiobenzophenone, thione-S, 4-phenyl-l,2,4-triazoline-3,5-dione, diphenyl-ketene and phenylisocyanate are added at the palladium and the enolate (a-C) carbon atoms, whereas methyl propiolate, methyl acrylate, and the methyl esters of maleic and fumaric acid form [2+3] cycloadducts with the «-carbon and the imino carbon atoms of the enolates under mild conditions. The structures of seven cycloadducts were determined by X-ray diffraction analyses.

Reaction of 2-[(E)-styryl]Quinazolin-4(3H)-one with Acetylenic Esters: Formation of Unexpected N-3 Alkenylation Products

2005 ◽  
Vol 2005 (7) ◽  
pp. 429-431 ◽  
Author(s):  
Tapasi Chatterjee ◽  
Subhagata Chattopadhyay ◽  
Ranjan Mukhopadhyay ◽  
Basudeb Achari ◽  
Santu Chakraborty ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Alder Reaction ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
Acetylenic Esters ◽  
X Ray ◽  
Methyl Propiolate ◽  
Diels Alder Reaction ◽  
Centrosymmetric Dimers

Attempted hetero Diels–Alder reaction with 2-[(E)-styryl]quinazolin-4(3H)-one (1) and dimethyl acetylenedicarboxylate (2) resulted in unexpected N-3 alkenylation products, 2-[(E)-styryl]-3-[(Z)-1,2-bis(methoxycarbonyl)vinyl]quinazolin-4(3H)-one (4a) and 3-[(E)-1,2-bis(methoxycarbonyl) vinyl] 2-[(E)-styryl]-quinazolin-4(3H)-one (4b) in low yield. Treating 1 and 2-methylquinazolin-4(3H)-one (9) with methyl propiolate (7) also furnished N-3 alkenylation products in low yield. The structure of 4b has been established by X-ray analysis. The molecules of 4b are linked by intermolecular C-H. … N hydrogen bonds into centrosymmetric dimers forming R22 (12) rings.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

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