scholarly journals A Leopard Cannot Change Its Spots: Unexpected Products from the Vilsmeier Reaction on 5,10,15-Tritolylcorrole

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3583
Author(s):  
Fabrizio Caroleo ◽  
Greta Petrella ◽  
Lorena Di Zazzo ◽  
Sara Nardis ◽  
Beatrice Berionni Berna ◽  
...  
Keyword(s):  
Inner Core ◽  
Vilsmeier Reaction ◽  
Reaction Products ◽  
Electrophilic Attack ◽  
Vilsmeier Reagent ◽  
Unique Reaction ◽  
The Way

The reaction of 5,10,15-tritolylcorrole with 3-dimethylaminoacrolein (3-DMA) and POCl3 gives a further example of the rebel reactivity of this contracted macrocycle. While no evidence was obtained for the formation of the expected β-acrolein corrole, the inner core substituted N21,N22-3-formylpropylcorrole and the 10-acrolein isocorrole were the reaction products. By increasing the temperature or the amount of the Vilsmeier reagent, the 10-isocorrole became the unique reaction product. The formation of the isocorrole by electrophilic attack of the Vilsmeier reagent to the 10-position of the corrole is unprecedented in the porphyrinoids field and it could pave the way for a novel route to the preparation of stable isocorroles.

Studies in Vilsmeier-Haack reaction: Reaction of 3-methyl-1-phenyl-4-arylidene-5-pyrazolone

1989 ◽  
Vol 54 (3) ◽  
pp. 706-712 ◽  
Author(s):  
Ibrahim M. A. Awad ◽  
Khairy M. Hassan
Keyword(s):  
Double Bond ◽  
Vilsmeier Reaction ◽  
Methyl Group ◽  
Vilsmeier Reagent ◽  
Carbon Double Bond ◽  
Pyrazolone Derivatives

The 3-methyl group in Ia, b has been found to undergo diformylation by Vilsmeier reagent to give the aminoacrolein derivatives (IIa, b). Treatment of IIa, b with different reagents affords the related 1-phenyl-4-arylidene-5-pyrazolone derivatives with different heterocyclic systems in the 3-position. The Vilsmeier reaction on pyrazolopyrazole (XIII) have been utilized to prove chemically that new heterocyclic systems are formed only at the 3-position and no addition on the carbon-carbon double bond in the conjugated system O=C-C=C-(B) takes place.

scholarly journals Forty years on: Edelman and Jefford's model of fructan metabolism

2008 ◽  
Vol 30 (2) ◽  
pp. 31-33
Author(s):  
Philip John
Keyword(s):  
Paper Chromatography ◽  
Reaction Products ◽  
Carbohydrate Polymers ◽  
Plant Biochemistry ◽  
Fructan Metabolism ◽  
Made In ◽  
The Way

Forty years ago, a paper was published which proposed a model for the synthesis and breakdown of plant fructans (inulin)1. The work was based on activities of enzymes that had been only partially purified, the reaction products were analysed by paper chromatography, and the proposed biosynthetic reactions differed from those of other carbohydrate polymers. Little progress was made in the subsequent 30 years, and a 1993 paper from the leading UK fructan laboratory referred to the model as “flawed”. However, work over the last 10 years with the purified enzymes and their cloned genes has demonstrated beyond any doubt that the enzymes involved in fructan synthesis and breakdown operate in just the way that Edelman and Jefford described them in 19681. This original and prescient paper deserves to be more widely recognized as a classic in plant biochemistry.

scholarly journals Interfacial reactivity of radionuclides: emerging paradigms from molecular-level observations

2011 ◽  
Vol 75 (4) ◽  
pp. 2379-2391 ◽  
Author(s):  
A. R. Felmy ◽  
E. S. Ilton ◽  
K. M. Rosso ◽  
J. M. Zachara
Keyword(s):  
Molecular Level ◽  
Surface Reactivity ◽  
Future Research ◽  
Reaction Products ◽  
Contaminant Migration ◽  
Electron Conduction ◽  
Field Samples ◽  
The Stability ◽  
Interfacial Reactivity ◽  
The Way

AbstractOver the past few decades an increasing array of molecular-level analytical probes has provided new detailed insight into mineral and radionuclide interfacial reactivity in subsurface environments. This capability has not only helped change the way mineral surface reactivity is studied but also how field-scale contaminant migration problems are addressed and ultimately resolved. Here we review relatively new interfacial reactivity paradigms and assess their implications for future research directions. Specific examples include understanding the following: the role of site-to-site electron conduction at mineral surfaces and through bulk mineral phases and the effects of local chemical environment on the stability of intermediate species in oxidation-reduction reactions and the importance of mechanistic reaction pathways for defining possible reaction products and thermodynamic driving force. The discussion also includes examples of how detailed molecular/microscopic characterization of field samples has changed the way complex contaminant migration problems are conceptualized and modelled.

The scope of the β-halogenation of triarylcorroles

2016 ◽  
Vol 20 (01n04) ◽  
pp. 465-474 ◽  
Author(s):  
Sara Nardis ◽  
Giuseppe Pomarico ◽  
Manuela Stefanelli ◽  
Sara Lentini ◽  
Daniel O. Cicero ◽  
...  
Keyword(s):  
Inner Core ◽  
2D Nmr ◽  
Silver Ion ◽  
Free Base ◽  
Reaction Products ◽  
Nmr Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Halogen Atoms

Functionalization of corrole at its peripheral positions is an intriguing field of research, since the unusual reactivity of this macrocycle usually makes it difficult to predict the reaction products. We have investigated the introduction of halogen atoms at the corrole β-positions by using haloacids as reagents. Different behavior, in terms of number and position of the units introduced, was observed: chlorination yielded mono and disubstituted corrole, whereas bromination only afforded mono-substitution, even if on different positions. Iodination did not occur on the corrole free base, while the protection of the inner core by chelation with silver ion gave better results and a symmetric diiodinated corrole was isolated. 2D NMR analysis and X-ray crystallography provided useful information about the site of these corrole functionalizations.

scholarly journals Biosynthesis Pathway of ADP-l-glycero-β-d-manno-Heptose in Escherichia coli

2002 ◽  
Vol 184 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Bernd Kneidinger ◽  
Cristina Marolda ◽  
Michael Graninger ◽  
Alla Zamyatina ◽  
Fiona McArthur ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Anion Exchange ◽  
High Performance ◽  
Inner Core ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Biosynthesis Pathway ◽  
Reaction Products ◽  
Novel Gene

ABSTRACT The steps involved in the biosynthesis of the ADP-l-glycero-β-d-manno-heptose (ADP-l-β-d-heptose) precursor of the inner core lipopolysaccharide (LPS) have not been completely elucidated. In this work, we have purified the enzymes involved in catalyzing the intermediate steps leading to the synthesis of ADP-d-β-d-heptose and have biochemically characterized the reaction products by high-performance anion-exchange chromatography. We have also constructed a deletion in a novel gene, gmhB (formerly yaeD), which results in the formation of an altered LPS core. This mutation confirms that the GmhB protein is required for the formation of ADP-d-β-d-heptose. Our results demonstrate that the synthesis of ADP-d-β-d-heptose in Escherichia coli requires three proteins, GmhA (sedoheptulose 7-phosphate isomerase), HldE (bifunctional d-β-d-heptose 7-phosphate kinase/d-β-d-heptose 1-phosphate adenylyltransferase), and GmhB (d,d-heptose 1,7-bisphosphate phosphatase), as well as ATP and the ketose phosphate precursor sedoheptulose 7-phosphate. A previously characterized epimerase, formerly named WaaD (RfaD) and now renamed HldD, completes the pathway to form the ADP-l-β-d-heptose precursor utilized in the assembly of inner core LPS.

The steric course of some electrophilic additions to the tetrahydropyridazine ring moiety of benzo[g]pyridazino[1,2-b]-phthalazine-6, 13-dione derivatives. II.

1997 ◽  
Vol 75 (3) ◽  
pp. 348-355 ◽  
Author(s):  
María Del Carmen Cano ◽  
Fernando Gómez-Contreras ◽  
Ana María Sanz ◽  
María Josefa Rodriguez Yunta
Keyword(s):  
Double Bond ◽  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Products ◽  
Electronic Effects ◽  
Electrophilic Attack ◽  
Diels Alder Reaction ◽  
Pyridazine Ring ◽  
Product Distributions ◽  
Electrophilic Additions

The stereochemical features involved in electrophilic additions to the ring A moiety in diazatetracyclic analogues of anthracyclinones have been investigated. The 1-methyl and 1,3-dimethyl derivatives 2a and 2b were selected as the substrates and made to react with bromine azide, iodine azide, and NBS–EtOH in order to evaluate the influence of the C-1 substituent on the product distributions. Electrophilic attack at the C-2/C-3 double bond occurs mainly in the less hindered anti fashion. The nucleophilic step governs the stereochemistry of the reaction products. Conformational factors are predominant over the steric and electronic effects originated by the ring A substituents, since axial antiparallel attack of the nucleophile on the intermediate epihalonium ion is clearly preferred to the equatorial approach. Keywords: diazatetracycles, Diels–Alder reaction, electrophilic addition, anthracyclinone analogues, pyridazine ring.

Self-sacrifice for in-group's history: A diachronic perspective

2018 ◽  
Vol 41 ◽  
Author(s):  
Maria Babińska ◽  
Michal Bilewicz
Keyword(s):  
Clinical Psychology ◽  
Historical Events ◽  
Emotional Events ◽  
Reciprocal Process ◽  
The Way

AbstractThe problem of extended fusion and identification can be approached from a diachronic perspective. Based on our own research, as well as findings from the fields of social, political, and clinical psychology, we argue that the way contemporary emotional events shape local fusion is similar to the way in which historical experiences shape extended fusion. We propose a reciprocal process in which historical events shape contemporary identities, whereas contemporary identities shape interpretations of past traumas.

What is the purpose of cognition?

2020 ◽  
Vol 43 ◽  
Author(s):  
Aba Szollosi ◽  
Ben R. Newell
Keyword(s):  
Infinite Number ◽  
Human Cognition ◽  
The Way

Abstract The purpose of human cognition depends on the problem people try to solve. Defining the purpose is difficult, because people seem capable of representing problems in an infinite number of ways. The way in which the function of cognition develops needs to be central to our theories.

Peculiarity Parameters

1976 ◽  
Vol 32 ◽  
pp. 233-254
Author(s):  
H. M. Maitzen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Theoretical Work ◽  
Observational Evidence ◽  
Rotator Model ◽  
Peculiar Behaviour ◽  
Field Spectrum ◽  
Oblique Rotator ◽  
Ap Stars ◽  
The Way

Ap stars are peculiar in many aspects. During this century astronomers have been trying to collect data about these and have found a confusing variety of peculiar behaviour even from star to star that Struve stated in 1942 that at least we know that these phenomena are not supernatural. A real push to start deeper theoretical work on Ap stars was given by an additional observational evidence, namely the discovery of magnetic fields on these stars by Babcock (1947). This originated the concept that magnetic fields are the cause for spectroscopic and photometric peculiarities. Great leaps for the astronomical mankind were the Oblique Rotator model by Stibbs (1950) and Deutsch (1954), which by the way provided mathematical tools for the later handling pulsar geometries, anti the discovery of phase coincidence of the extrema of magnetic field, spectrum and photometric variations (e.g. Jarzebowski, 1960).

Lead aspartate: a new en bloc stain for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 34-35
Author(s):  
J.R. Walton
Keyword(s):  
Electron Microscopy ◽  
Calcium Ion ◽  
Enzyme Reaction ◽  
Lead Citrate ◽  
Reaction Products ◽  
En Bloc ◽  
Thin Sections ◽  
Lead Salts ◽  
Thin Sectioning ◽  
High Alkalinity

In electron microscopy, lead is the metal most widely used for enhancing specimen contrast. Lead citrate requires a pH of 12 to stain thin sections of epoxy-embedded material rapidly and intensively. However, this high alkalinity tends to leach out enzyme reaction products, making lead citrate unsuitable for many cytochemical studies. Substitution of the chelator aspartate for citrate allows staining to be carried out at pH 6 or 7 without apparent effect on cytochemical products. Moreover, due to the low, controlled level of free lead ions, contamination-free staining can be carried out en bloc, prior to dehydration and embedding. En bloc use of lead aspartate permits the grid-staining step to be bypassed, allowing samples to be examined immediately after thin-sectioning.Procedures. To prevent precipitation of lead salts, double- or glass-distilled H20 used in the stain and rinses should be boiled to drive off carbon dioxide and glassware should be carefully rinsed to remove any persisting traces of calcium ion.

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