Synthesis and antimicrobial studies on novel chloro-fluorine containing hydroxy pyrazolines.

Publisher Summary The chapter focuses tautomerism and electronic Structure of biological pyrimidines. The understanding of the tautomeric properties of the purine and pyrimidine bases of the nucleic acids and the determination of the electronic properties of the principal tautomers are of fundamental importance in molecular biology, in particular, in connection with the theory of mutations. The principal tautomeric properties of the fundamental biological pyrimidines-cytosine, uracil, and thymine-are due to the presence in these N-heteroaromatic compounds of electron-donor substituents, such as NH and OH, and of SH in some important analogs. The chapter discusses tautomerism of cytosine and presents the essential physicochemical properties of cytosine and some of its derivatives and to the theoretical interpretation of these properties. The chapter also discusses tautomerism and physicochemical properties of uracil and thymines and to give a theoretical interpretation of these properties. The study of the optical properties of naturally occurring pyrimidines and purines is a problem of great interest in molecular biology. The knowledge of these properties provide information important for understanding energy transfer, hypochromism, photochemistry, optical rotatory dispersion, circular dichroism, magnetic optical rotator dispersion, and magnetic circular dichroism of DNA, RNA, and related model systems. Tautomerism, electronic structures, and spectra of rare pyrimidine bases of the nucleic acids have also been discussed.

Taulomerism and Electronic Structure of Biological Pyrimidines

An efficient "one-step" synthesis of cyclic amidines and guanidines has been developed. Treatment of cyclic amides and ureas with benzotriazol-1-yloxytris(dimethylamino)phosphonium hexafluorophosphate (BOP), base, and nitrogen nucleophiles leads to the formation of the corresponding cyclic amidines and guanidines, typically in good to excellent yields. This method has also been used to prepare heteroaryl ethers and thioethers using phenol and thiophenol nucleophiles. Time course NMR and HPLC-MS studies have facilitated explicit characterization of the proposed intermediates (the phosphonium salt and HOBt adduct); the data reveal a stepwise reaction pathway.

The scope and mechanism of phosphonium-mediated S(N)Ar reactions in heterocyclic amides and ureas.

Synthesis and pharmacological activities of xanthone derivatives as α-glucosidase inhibitors

The review deals with the Ullmann condensation as the most important method for the synthesis of aromatic ethers. The available information about the dependence of the reactivity of the reactants on structure and the reaction mechanism is examined and the experimental condensation conditions are discussed. The bibliography includes 241 references.

https://iopscience.iop.org/article/10.1070/RC1974v043n08ABEH001845/pdf

The Ullmann Ether Condensation

Die Synthese einer Reihe von 4-Hydroxy-1-thiacumarinen mit Alkyl- und Halogensubstituenten am Benzolkern und die Darstellung einer Anzahl 3-Alkyl-4-hydroxy-1-thiacumarine wird beschrieben.

Die Synthese von 4-Hydroxy-1-thiacumarinen 2. Mitt.†‡

Nach der Methode vonE. Ziegler und Mitarb. zur Synthese von 4-Hydroxycumarinen wird eine Anzahl von 4-Hydroxythiocumarinen dargestellt und uber deren Eigenschaften berichtet.

Zur Chemie der Antikoagulantien

Die Synthese linearer Furanoxanthone (5-Oxo-5H-furo[3.2-b]xanthene) aus 2-Hydroxy-3-acetyl-xanthonen wird an den Beispielen 5-Oxo-3-methyl- und 5-Oxo-3.7-dimethyl-5Hfuro[3.2-b]xanthen (4a, b) beschrieben.

Furan‐Verbindungen, X

Results of bacteriological tests with some halogen substituted chalkones corroborates previous reports that the bacteriostatic action of αβ-unsaturated ketones increases appreciably with the introduction of hydroxyl and halogen substituents

A note on the antibacterial action of some halogen substituted chalkones.

Es wird die Darstellung einer Anzahl von 3,3′-Methylen-bis-(4-hydroxy-1-thiacumarinen), von 3,3′-Aryliden-bis-(4-hydroxy-1-thiacumarinen) mit verschiedenen Substituenten im aromatischen Ring und einiger 3,3′-Aryliden-4,4′-epoxydithiacumarine beschrieben. Die Bildung von Anhydroverbindungen bei Verwendung von Salicyladehyd als Aldehydkomponente bei derartigen Kondensationen wird diskutiert.

Untersuchungen an 4-Hydroxy-1-thiacumarinen, 3. Mit.: Reaktionen des 4-Hydroxy-1-thiacumarins mit aliphatischen und aromatischen Aldehyden und Dehydratation ihrer Kondensationsprodukte

S. Rajagopal

Papers

Die Synthese von 4-Hydroxy-1-thiacumarinen 2. Mitt.†‡

Zur Chemie der Antikoagulantien

Furan‐Verbindungen, X

A note on the antibacterial action of some halogen substituted chalkones.

Untersuchungen an 4-Hydroxy-1-thiacumarinen, 3. Mit.: Reaktionen des 4-Hydroxy-1-thiacumarins mit aliphatischen und aromatischen Aldehyden und Dehydratation ihrer Kondensationsprodukte