Stereoelectronic power of oxygen in control of chemical reactivity: the anomeric effect is not alone

2021 ◽  
Author(s):  
Igor V. Alabugin ◽  
Leah Kuhn ◽  
Michael G. Medvedev ◽  
Nikolai V. Krivoshchapov ◽  
Vera A. Vil’ ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Chemical Reactivity ◽  
Anomeric Effect

The chameleonic properties of oxygen accounts for the diverse reactivity of O-functionalities and their profound role in organic synthesis.

Prediction of Chemical Reactivity and Design of Organic Synthesis

1988 ◽  
pp. 343-359 ◽  
Author(s):  
Johann Gasteiger ◽  
Michael G Hutchings ◽  
Heinz Saller ◽  
Peter Löw
Keyword(s):  
Organic Synthesis ◽  
Chemical Reactivity

MCDCalc: Markov Chain Molecular Descriptors Calculator for Medicinal Chemistry

2020 ◽  
Vol 20 (4) ◽  
pp. 305-317 ◽  
Author(s):  
Paula Carracedo-Reboredo ◽  
Ramiro Corona ◽  
Mikel Martinez-Nunes ◽  
Carlos Fernandez-Lozano ◽  
Georgia Tsiliki ◽  
...  
Keyword(s):  
Markov Chain ◽  
Organic Synthesis ◽  
Medicinal Chemistry ◽  
Molecular Descriptors ◽  
Chemical Reactivity ◽  
Single Molecules ◽  
Enantiomeric Excess ◽  
Molecular Systems ◽  
Specificity And Sensitivity ◽  
Metabolic Reactions

Aim: Cheminformatics models are able to predict different outputs (activity, property, chemical reactivity) in single molecules or complex molecular systems (catalyzed organic synthesis, metabolic reactions, nanoparticles, etc.). Background: Cheminformatics models are able to predict different outputs (activity, property, chemical reactivity) in single molecules or complex molecular systems (catalyzed organic synthesis, metabolic reactions, nanoparticles, etc.). Objective: Cheminformatics prediction of complex catalytic enantioselective reactions is a major goal in organic synthesis research and chemical industry. Markov Chain Molecular Descriptors (MCDs) have been largely used to solve Cheminformatics problems. There are different types of Markov chain descriptors such as Markov-Shannon entropies (Shk), Markov Means (Mk), Markov Moments (πk), etc. However, there are other possible MCDs that have not been used before. In addition, the calculation of MCDs is done very often using specific software not always available for general users and there is not an R library public available for the calculation of MCDs. This fact, limits the availability of MCMDbased Cheminformatics procedures. Methods: We studied the enantiomeric excess ee(%)[Rcat] for 324 α-amidoalkylation reactions. These reactions have a complex mechanism depending on various factors. The model includes MCDs of the substrate, solvent, chiral catalyst, product along with values of time of reaction, temperature, load of catalyst, etc. We tested several Machine Learning regression algorithms. The Random Forest regression model has R2 > 0.90 in training and test. Secondly, the biological activity of 5644 compounds against colorectal cancer was studied. Results: We developed very interesting model able to predict with Specificity and Sensitivity 70-82% the cases of preclinical assays in both training and validation series. Conclusion: The work shows the potential of the new tool for computational studies in organic and medicinal chemistry.

scholarly journals Correction: Stereoelectronic power of oxygen in control of chemical reactivity: the anomeric effect is not alone

2021 ◽  
Author(s):  
Igor V. Alabugin ◽  
Leah Kuhn ◽  
Michael G. Medvedev ◽  
Nikolai V. Krivoshchapov ◽  
Vera A. Vil' ◽  
...  
Keyword(s):  
Chemical Reactivity ◽  
Anomeric Effect

Correction for ‘Stereoelectronic power of oxygen in control of chemical reactivity: the anomeric effect is not alone’ by Igor V. Alabugin et al., Chem. Soc. Rev., 2021, DOI: 10.1039/d1cs00386k.

scholarly journals Dearomatization of a 3-Hydroxypyridine Through an Unexpected Oxidative Deformylation Process: An Entry to Azacyclohexadienones

Synlett ◽  
2020 ◽  
Vol 31 (15) ◽  
pp. 1497-1500
Author(s):  
Cyrille Sabot ◽  
Afef Mabrouki ◽  
Patricia Le Nahenec-Martel ◽  
Abdelkader Kriaa ◽  
Ahmed Hedhli ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Chemical Reactivity ◽  
Oxidative Dearomatization ◽  
Type Compound

Phenols are well-known precursors of cyclohexadienones, which have widespread applications in organic synthesis. In contrast, their hydroxypyridine counterparts have not been explored yet. An unprecedented oxidative dearomatization of a 3-hydroxypyridine involving an unexpected deformylation step is reported. The chemical reactivity of the resulting unreported azacyclohexadiene-type compound was also explored.

Preface

2007 ◽  
Vol 79 (2) ◽  
pp. iv
Author(s):  
Guillermo Delgado
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Latin American ◽  
Chemical Reactivity ◽  
50Th Anniversary ◽  
Structural Complexity ◽  
Chemical Society ◽  
Scientific Program ◽  
Chemical Research ◽  
Organic Selenium

Organic synthesis continues to grow and develop impressively in response to new research challenges at the boundaries of structural complexity, while playing a central role in the industrial activities and applications of the chemical sciences. The International Conferences on Organic Synthesis (ICOS), which have been organized biennially around the world since 1976 under IUPAC sponsorship, faithfully reflect this growth and development.The 16th event in this series (ICOS-16) was held in Mérida, México, from 11 to 15 June 2006. The scientific program included 22 plenary and invited speakers, as well as 36 experts who participated in symposia on medicinal chemistry, organocatalysis, enantioselective synthesis of β-amino acids, organolithium compounds in organic synthesis, organic selenium and tellurium compounds in organic synthesis, and applications of microwaves in organic synthesis. In addition, almost 300 posters covering all aspects of modern organic synthesis were displayed by scientists and research scholars. The strong Latin American participation in this feature of the program, followed by those of European, North American, and Asian delegates, attested to the growing contribution of this region to chemical research in organic synthesis. Overall, the scientific program offered comprehensive and fruitful coverage of organic synthesis from a variety of different perspectives.The Mexican Academy of Sciences and the Mexican Chemical Society (celebrating its 50th Anniversary) featured as cosponsors of ICOS-16 together with IUPAC. This was the second occasion that an IUPAC-sponsored conference has been held in Mexico, the first being the 6th International Symposium on Natural Products Chemistry in Mexico City, in 1969. ICOS-16 attracted almost 500 delegates from 40 countries, mainly those of Latin America, a gratifyingly high proportion of whom were younger scientists.This issue of Pure and Applied Chemistry contains a representative selection of papers based upon lectures delivered at ICOS-16. The theme of synthesis of natural products was covered by M. Brimble (New Zealand), L. C. Dias (Brazil), and C. Gennari (Italy). Different aspects on methodology and control of chemical reactivity were presented by J. Tamariz (Mexico), S. F. Martin (USA), S. Ma (China), and Ph. Renaud (Switzerland). Organic synthesis using phosphorous was covered by R. Réau (France) and C. Nájera (Spain). The broad topic of catalysis was presented by S. Kobayashi (Japan) and C. Crudden (USA). New insights on synthesis using epoxides and aziridines were disclosed by D. Hodgson (UK) and F. McDonald (USA).Organic synthesis is a fascinating field of chemistry that has often been compared with art. The control of regio-, stereo-, and site selectivity demands deep insight into chemical reactivity as well as knowledge of new and old methodology and catalysis, and the ability to combine these creatively in sustainable processes in order to achieve specific objectives. Despite remarkable progress during recent years, efficient synthesis of specific organic compounds with tailored activities and properties will continue to challenge future generations of chemists. Further progress of organic synthesis will be covered during the next conference in this series (ICOS-17), which will take place in Korea during 2008.Thanks are due to members of the ICOS-16 Committees, to all participants, and to authors contributing to this issue.Guillermo DelgadoConference Editor

Spatially Resolved Photoelectron Spectroscopy: Recent Progress and Future Plans

1990 ◽  
Vol 48 (2) ◽  
pp. 388-389
Author(s):  
A. M. Bradshaw
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Reactivity ◽  
Target Material ◽  
Orbital Energy ◽  
Light Sources ◽  
Analytical Technique ◽  
Hartree Fock ◽  
Spatially Resolved ◽  
Koopmans Theorem ◽  
Surface Analytical Technique

X-ray photoelectron spectroscopy (XPS or ESCA) was not developed by Siegbahn and co-workers as a surface analytical technique, but rather as a general probe of electronic structure and chemical reactivity. The method is based on the phenomenon of photoionisation: The absorption of monochromatic radiation in the target material (free atoms, molecules, solids or liquids) causes electrons to be injected into the vacuum continuum. Pseudo-monochromatic laboratory light sources (e.g. AlKα) have mostly been used hitherto for this excitation; in recent years synchrotron radiation has become increasingly important. A kinetic energy analysis of the so-called photoelectrons gives rise to a spectrum which consists of a series of lines corresponding to each discrete core and valence level of the system. The measured binding energy, EB, given by EB = hv−EK, where EK is the kineticenergy relative to the vacuum level, may be equated with the orbital energy derived from a Hartree-Fock SCF calculation of the system under consideration (Koopmans theorem).

Cluster analysis for large data sets: applications to individual aerosol particles from the mid-pacific

1992 ◽  
Vol 50 (2) ◽  
pp. 1488-1489
Author(s):  
Thomas W. Shattuck ◽  
James R. Anderson ◽  
Neil W. Tindale ◽  
Peter R. Buseck
Keyword(s):  
Cluster Analysis ◽  
Chemical Reactivity ◽  
Large Data ◽  
Large Data Sets ◽  
Particle Analysis ◽  
Data Sets ◽  
Halogen Chemistry ◽  
Complete Study ◽  
Components Analysis ◽  
Automated Scanning

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.

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