Synthesis of N-Phenylsulfonyl Protected Furo[3,2-b]pyrroles

1994 ◽  
Vol 59 (2) ◽  
pp. 499-502 ◽  
Author(s):  
Vladimír Bobošík ◽  
Alžbeta Krutošíková
Keyword(s):  
Nitrogen Atom ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
The Other ◽  
Lithium Salts ◽  
Benzenesulfonyl Chloride ◽  
Heterocyclic Molecules ◽  
Other Hand ◽  
Indole Series

Protection of nitrogen atom of heterocyclic molecules, such as indole and pyrrole types, enables various reactions of these systems. N-Phenylsulfonyl derivatives, which have been widely used for this purpose, were prepared in the indole series by the reaction of N-sodium and N-lithium salts with benzenesulfonyl chloride. This method requires waterfree and oxygenfree conditions. On the other hand, the phase transfer catalysis conditions used in this work obviates these disadvantages. We therefore selected the latter method for the preparation of variously substituted 4-phenylsulfonylfuro[3,2-b]pyrroles (I - VII) and 1-phenylsulfonylbenzo[b]furo[3,2-b]pyrroles (VIII - IX).

Nucleophilic reactions in the indole series: displacement of bromine under phase transfer catalysis

Tetrahedron ◽  
2008 ◽  
Vol 64 (51) ◽  
pp. 11625-11631 ◽  
Author(s):  
Paola Barraja ◽  
Patrizia Diana ◽  
Anna Carbone ◽  
Girolamo Cirrincione
Keyword(s):  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Nucleophilic Reactions ◽  
Indole Series

Alkylation by secondary alcohols. I. The reaction of xanthydrol with some N1-monosubstituted sulfanilamides and related compounds

1967 ◽  
Vol 45 (13) ◽  
pp. 1411-1424 ◽  
Author(s):  
R. E. Moskalyk ◽  
L. G. Chatten
Keyword(s):  
Nitrogen Atom ◽  
Tautomeric Form ◽  
Heterocyclic Ring ◽  
The Other ◽  
Secondary Alcohols ◽  
Amino Group ◽  
Aromatic Character ◽  
Carbonium Ion ◽  
Other Hand ◽  
Related Compounds

Sulfanilamides were found to undergo alkylation with xanthydrol, yielding either mono- or di-xanthenyl derivatives. The site of substitution, common to all sulfanilamides having a free p-amino group, was shown to be the N4-position in the sulfanilamide molecule. Three additional unique reactive sites were observed. Sulfanilamides carrying a thiazole, thiadiazole, or pyridazine substituent in the N1-position were also alkylated on the annular nitrogen atom of the heterocyclic ring, the reaction having occurred from the imido tautomeric form. Sulfisoxazole (IK), on the other hand, reacted from the amido form to give the N1,N4-dixanthenyl derivative. Sulfadimethoxine (Ih) was substituted at carbon, as well as at nitrogen, to yield N4-xanthenyl-N1-(2,6-dimethoxy-5-(9-xanthenyl)-4-pyrimidyl)sulfanilamide.Sulfanilamides possessing pKa values of about 5.5 were found to be sufficiently acidic to catalyze their own reaction with xanthydrol, and no external catalyst was necessary. The exceptional ease of formation of the xanthylium ion was postulated to be associated with the resulting stability of this carbonium ion by virtue of its acquired aromatic character.

scholarly journals The First Glycosides with Pyrazolo[3,4-C]isoquinoline Aglycone Moiety. Synthesis and NMR Structure Investigation

2020 ◽  
Author(s):  
Natalia Bogdan ◽  
SERGE BOGZA ◽  
Dalila Bousta ◽  
Tatiana Chupakhina ◽  
Andriy Grafov ◽  
...  
Keyword(s):  
Biological Activity ◽  
Nitrogen Atom ◽  
High Stability ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Pyrazole Ring ◽  
Nmr Structure ◽  
Structure Investigation ◽  
Nmr Study

<div>we describe the methods of obtaining N- and O-glycosides with the pyrazolo[3,4-c]isoquinoline as aglycone moiety. O-glycosides are obtained in good yields under phase transfer catalysis. Mercury (II) bromide is used for glycosylation of nitrogen atom at pyrazole ring. NMR study of the structure has shown high stability of the glycoside residue proton signals. Studies of the biological activity of the compounds is underway and will be presented in due course.</div>

Synthesis of Some New Bis[1-(2-aroyl-3-aryl)cyclopropylcarbonyl]benzenes and Pyridines under Phase Transfer Catalysis (PTC) Method

1993 ◽  
Vol 58 (6) ◽  
pp. 1437-1444 ◽  
Author(s):  
Dandu Bhaskar Reddy ◽  
Biradavolu Seenaiah ◽  
Adivireddi Padmaja ◽  
Pallela Venkata Ramana Reddy
Keyword(s):  
Spectral Data ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
The Other

Some new bis[1-(2-aroyl-3-aryl)cyclopropylcarbonyl]benzenes and pyridines IV - VI have been prepared by the cycloaddition of dimethylsulfonium phenacylide to 1,1'-(1,3-, 1,4-phenylene, and 2,6-pyridylene)-bis(3-aryl-2-propen-1-ones) I - III by adopting two different methods. The advantages of the PTC method over the other have been discussed. The structures of the compound have been confirmed by spectral data.

Etude en résonance magnétique nucléaire du 13C des paramètres de substitution de la fonction azide

1977 ◽  
Vol 55 (15) ◽  
pp. 2829-2834 ◽  
Author(s):  
A. Pancrazi ◽  
I. Kaboré ◽  
B. Delpech ◽  
A. Astier ◽  
Q. Khuong-Huu ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Spatial Arrangement ◽  
The Other ◽  
Azide Group ◽  
Other Hand ◽  
Résonance Magnétique ◽  
C Nmr

The various effects (α, β, γ and δ) on the 13C nmr of azido steroids have been measured. For cyclohexane azides constrained to equatorial and axial configurations, the α-effects were determined to be 33.6 and 31.2 ppm. Both γ- and δ-effects have magnitudes near those for OH and NH2 groups. On the other hand, the β-effect of the azides is slightly smaller than those of hydroxyls or amines as its magnitude is reduced by a γ-effect of the second nitrogen atom of the azide group. This additional γ-effect is a function of the spatial arrangement of the Cβ—H bond with respect to the azide group. [Journal translation]

scholarly journals The First Glycosides with Pyrazolo[3,4-C]isoquinoline Aglycone Moiety. Synthesis and NMR Structure Investigation

2020 ◽  
Author(s):  
Natalia Bogdan ◽  
SERGE BOGZA ◽  
Dalila Bousta ◽  
Tatiana Chupakhina ◽  
Andriy Grafov ◽  
...  
Keyword(s):  
Biological Activity ◽  
Nitrogen Atom ◽  
High Stability ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Pyrazole Ring ◽  
Nmr Structure ◽  
Structure Investigation ◽  
Nmr Study

<div>we describe the methods of obtaining N- and O-glycosides with the pyrazolo[3,4-c]isoquinoline as aglycone moiety. O-glycosides are obtained in good yields under phase transfer catalysis. Mercury (II) bromide is used for glycosylation of nitrogen atom at pyrazole ring. NMR study of the structure has shown high stability of the glycoside residue proton signals. Studies of the biological activity of the compounds is underway and will be presented in due course.</div>

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

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