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.

Antiasthma agents. 1. 4-Oxo-4H-(1) benzothieno-(3,2-b)pyran-2-carboxylic acid and 4-oxo-4H-(1)benzofuro(3,2-b)pyran-2-carboxylic acid.

Taulomerism and Electronic Structure of Biological Pyrimidines

Publisher Summary The chapter focuses on the recent advances in the chemistry of benzo[b]furan and its derivatives. The chemistry of benzofuran derivatives has developed in a spectacular fashion: research in this field has reached such a scale that the period covered by this review has given rise to a larger number of papers than that between 1870 and 1950. It has proceeded along the following three main lines: (1) Extraction, determination of structures, partial or total synthesis of the simple or complex heterocyclic derivatives constituting the natural benzofuran derivatives of vegetable origin. (2) Synthesis of benzofuran derivatives with physiological, pharmacological, therapeutic, or toxic properties. (3) Studies on the reactivity of benzofuran and its derivatives from the chemical and physical point of view. Many substances with physiological, pharmacological, therapeutic, or toxic properties are to be found among natural products with a benzofuran ring. As to synthetic benzofuran derivatives prepared for the study of their physiological properties, their number is large. Benzofuran is prepared in semicommercial amounts. The chapter discusses the presence of benzofurans in coal tar and in petroleum. Natural benzofuran derivatives have also been discussed. The numerous syntheses of the benzofuran ring may be classified under four headings: (1) Formation of the heterocyclic ring from an aromatic substrate (2) formation of the heterocyclic ring from a nonaromatic substrate (3) fusion of the benzene ring to a furan substrate (4) formation of the heterocyclic ring from other heterocyclic compounds.

Recent Advances in the Chemistry of Benzo[b]furan and Its Derivatives. Part I: Occurrence and Synthesis

Application of directed metalation in synthesis. Part 8: Interesting example of chemoselectivity in the synthesis of thioaurones and hydroxy ketones and a novel anionic ortho-Fries rearrangement used as a tool in the synthesis of thienopyranones and thiafluorenones

Publisher Summary This chapter discusses the development of compounds of a specific type to be used in the treatment of asthma and associated diseases. Contribution has also been made by other classes of drugs in this therapeutic area—namely, the bronchodilators (β2-adrenoreceptor stimulants, phosphodiesterase inhibitors), ediator antagonists (antihistamines, anticholinergics), and corticosteroids. The drug therapy of asthma and related diseases has been greatly improved during the past several years. Compounds that are claimed to have mast-cell-stabilizing properties, but whose primary mode of action is that of antagonizing histamine at H receptors, have also become available for therapeutic use. Problems in this field of research have been referred to and consist essentially of an incomplete knowledge of the mode of action of sodium cromoglycate, the lack of predictability of activity in animal or in vitro models and in human provocation tests for therapeutic activity, and the difficulties inherent in therapeutic trials in such a variable disease as asthma.

The search for antiallergic drugs for the treatment of asthma--problems in finding a successor to sodium cromoglycate.

N-Alkyl-anthranilsauren reagieren mit Chloraceton/K2CO3 unter Bildung von 1-Alkyl-2-acetyl-3-hydroxy-indolen 3. Die 1,3-Dicarbonylverbindungen 3 kondensieren mit Oxalsaurediestern zu den 1,3,5,6-Tetracarbonylverbindungen 5, die beim Erhitzen in mit HCl-gesattigten Alkoholen zu den 4-Pyron-2-carbonsaureestern 6 cyclisieren. Aus 6 erhalt man die antiallergisch wirksamen Sauren 8, die sich zu den Pyrono[3,2-b]indolen 9 decarboxylieren lassen. Kondensation von 5 mit Orthoameisensaureestern/Acetanhydrid ergibt die 4-Pyron-3-ketocarbonsaureester 7, 6 und 9 werden in die Thiocarbonylverbindungen 11 und 12 uberfuhrt. Aus 6c und Ammoniak erhalt man das Saureamid 10.



1,3-Dicarbonyl Compounds, XV: 4,5-Dihydro-5-alkyl-4-oxopyrano[3,2-b]indoles



N-Alkylanthranilic acids react with chloroacetone/K2CO3 to form the 1-alkyl-2-acetyl-3-hydroxy-indoles 3. The 1,3-dicarbonyl compounds 3 condense with dialkyl oxalates to yield the 1,3,5,6-tetra-carbonyl compounds 5, which cyclize on heating with alcohols, saturated with HCl, to form the alkyl 4-pyrone-2-carboxylates 6. The acids 8, obtained from 6, possess antiallergic activity. Decarboxylation of 8 affords the pyrono[3,2-b]indoles 9. Condensation of 5 with triethyl orthoformate/acetic anhydride yield the alkyl 4-pyrone-3-ketocarboxylates 7. Compounds 6 and 9 are converted to the thiocarbonyl compounds 11 and 12. The amide 10 is obtained from 6c by reaction with ammonia.

Antiasthma agents. 1. 4-Oxo-4H-(1) benzothieno-(3,2-b)pyran-2-carboxylic acid and 4-oxo-4H-(1)benzofuro(3,2-b)pyran-2-carboxylic acid.

Citations

Taulomerism and Electronic Structure of Biological Pyrimidines

Recent Advances in the Chemistry of Benzo[b]furan and Its Derivatives. Part I: Occurrence and Synthesis

Application of directed metalation in synthesis. Part 8: Interesting example of chemoselectivity in the synthesis of thioaurones and hydroxy ketones and a novel anionic ortho-Fries rearrangement used as a tool in the synthesis of thienopyranones and thiafluorenones

The search for antiallergic drugs for the treatment of asthma--problems in finding a successor to sodium cromoglycate.

Untersuchungen an 1,3‐Dicarbonylverbindungen, 15. Mitt. 4,5‐Dihydro‐5‐alkyl‐4‐oxo‐pyrano[3,2‐b]indole