Organic Chemistry By Dr. I. L. Finar. Vol. 2: Stereochemistry and the Chemistry of Natural Products. Pp. xi + 733. (London and New York: Longmans, Green and Co., Ltd., 1956.) 40s. net.

Advanced Organic Chemistry

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The Nature Of The Chemical Bond

Chemistry remains an experimental science. The theory of chemical bonding leaves much to be desired. Yet, the past 20 years have been marked by a fruitful symbiosis of organic chemistry and molecular orbital theory. Of necessity this has been a marriage of poor theory with good experiment. Tentative conclusions have been arrived a t on the basis of theories which were such a patchwork on approximations that they appeared to have no right to work; yet, in the hands of clever experimentalists, these ideas were transformed into novel molecules with unusual properties. In the same way, by utilizing the most simple but fundamental concepts of molecular orbital theory we have in the past 3 years been able to rationalize and predict the stereochemical course of virtually every concerted organic reaction.' In our work we have relied on the most basic ideas of molecular orbital theory-the concepts of symmetry, overlap, interaction, bonding, and the nodal structure of wave functions. The lack of numbers in our discussion is not a weakness-it is its greatest strength. Precise numerical values would have to result from some specific sequence of approximations. But an argument from first principles or symmetry, of necessity qualitative, is in fact much stronger than the deceptively authoritative numerical result. For, if the simple argument is true, then any approximate method, as well as the now inaccessible exact solution, must obey it. The simplest description of the electronic structure of a stable molecule is that i t is characterized by a finite band of doubly occupied electronic levels, called bonding orbitals, separated by a gap from a corresponding band of unoccupied, antiboding levels as well as a continuum of higher levels. The magnitude of the gap may range from 40 kcal/mole for highly delocalized, large aromatic systems to 250 kcal/mole for saturated hydrocarbons. It should be noted in context that socalled nonbonding electrons of heteroatoms are in fact bonding. Consider a simple reaction of two molecules to give a third species, proceeding in a nonconcerted manner through a diradical intermediate I. A + B + [I] + C

The Conservation of Orbital Symmetry (福井謙一とフロンティア軌導理論) -- (参考論文)

A novel series of quinolone-based heterocyclic derivatives including thiadiazine, thiadiazoles, and triazole were synthesized and their in vitro antibacterial activity against Gram-positive and Gram-negative bacteria were evaluated. Newly synthesized derivatives have been obtained in good yields ranging from 65 to 80%. The synthesized derivatives have been characterized and their structures identified using spectroscopic analysis including NMR, FT-IR, and mass techniques. Most of compounds exhibited moderate-to-good antibacterial activity against all four bacterial strains and are significantly more active than ampicillin. Compounds showed relatively good anti-bacterial activity compared to moderate activity of other compounds. The results obtained herein are important for further structure modifications of quinoline bearing heterocyclic moiety and the exploitation of the therapeutic potential of quinoline derivatives as antibacterial agents.

Design, synthesis, and biological evaluation of new quinoline-based heterocyclic derivatives as novel antibacterial agents

Design, synthesis, and biological evaluation of amide derivatives of imidazo[2,1-b][1,3,4]thiadiazole as anticancer agents

The density functional theory (DFT) and thermodynamic analyses were applied to study the stability and chemical reactivity of the synthesized CMPIP {2-chloro-4-(4-(1-methyl-1H-pyrazole-4-yl)-1H-imidazole-5-yl) pyridine} and MPIMPPA {4-(4-(1-methyl-1H-pyrazole-4-yl)- 1H-imidazole-5-yl)-N-(4-morpholino phenyl) pyridin-2-amine}. The results concluded that the CMPIP compound is more stable than MPIMPPA. The antifungal study was confirmed that the MPIMPPA has a higher inhibition zone against Aspergillus niger (A. niger), as compared to the standard drug used, while the CMPIP compound showed weaker activity than the positive control.

Antifungal activity and theoretical study of synthesized pyrazole-imidazole hybrids

Theoretical investigation for synthesis and characterization of two novel disubstituted imidazoles using microwave

In this work, series of substituted α, β-unsaturated carbonyl compounds (A1-8) had been prepared using Claisen-Schmidt condensation. Also, series of substituted Schiff bases (N-arylidene-4-picolyamine) (B1-6) were prepared by the condensation of 4-picolyamine with various aromatic aldehydes. The reaction of the above mentioned materials (A+B) afforded the desired products [Spiropyrrolidines (S1-15)]. The reaction occurred through the formation of azallyl anion which acted as a nucleophile that has the ability to attack the exocylic double bond of chalcones through the 1,3-anionic cycloaddition mechanism to form the product. The structure for all synthesized compounds (chalcones, Schiff bases, pyrrolidines) had been confirmed by the spectral data obtained by (UV, IR, H-NMR) as well as the determination of physical properties.

/pdf/synthesis-of-spiropyrrolidines-via-1-3-anionic-cycloaddition-5bn8bfbtbu.pdf

Synthesis of Spiropyrrolidines via 1, 3 Anionic Cycloaddition

The rate of reaction between Schiff bases (N-Benzylidene-4-Picolyamine) and its derivatives with Chalcone(2-benzylidine-1-tetralone) to form spiropyrrolidine have been studied in DMF. This study occurred in two steps: The first step involved following the formation of intermediate by Fluorescence. The study indicated a pseudo first order dependence with rates 3,4-Dimethoxy> p-OCH3 > p-CH3 > H > P-Cl > P-NO2 at any temperature (298-318 K). The effect of substituents on the rate showed that electronic factors, inductive, conjugative and steric factors play reasonable role on the stability of the intermediates. The second step involved the disappearance of intermediate (cyclization process) to form the final product (spiropyrrolidine). This step was followed by UV technique and indicated a first order dependence with rates P-NO2 > p-Cl > H > p-CH3 > pOCH3 > 3,4-Dimethoxy. A suitable mechanism for this type of reaction, which is consistent with the results, has been postulated.

/pdf/kinetic-studies-of-the-formation-of-number-of-1ihnnt0vdy.pdf

Kinetic Studies of the Formation of Number of Spiropyrrolidine

In this work we present a study about the molecular structure and electrochemical behavior of a series of substituted 2´-hydroxychalcones and their conversion to the corresponding flavanones. The study was performed using density function theory (DFT) based on B3YLP with 6-311G basis set was used in order to investigate the effect of the electronic and structure properties for the isomerization process. Reactants, intermediates and products have an equilibrium state and one transition state that possess one imaginary frequency. The optimized structure, total energies ,hardness ,polarizability ,chemical potential and electrophilicity index were calculated. The relative energy calculated using DFT corresponds with those calculated in a practical way by the use of HPLC technique, the hardness profile along the reaction path in agreement with maximum hardness principle, and the minimum polarizability principle is obeyed in all cases.

https://ejchem.journals.ekb.eg/article_116877_6f68c2fa13f837fa74f095cdc6d56194.pdf

Omar A. Shareef

Papers

Antifungal activity and theoretical study of synthesized pyrazole-imidazole hybrids

Theoretical investigation for synthesis and characterization of two novel disubstituted imidazoles using microwave

Synthesis of Spiropyrrolidines via 1, 3 Anionic Cycloaddition

Kinetic Studies of the Formation of Number of Spiropyrrolidine

Theoretical Study for Isomerization of Some 2´-Hydroxychalcone Derivative by Using DFT Calculation