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

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

Synthesis, reactions and biological activities of furochromones: A review

Synthesis and estrogen receptor binding affinities of novel pyrrolo[2,1,5-cd]indolizine derivatives.

The Michael condensation in its original scope is the addition of an addend or donor containing an alpha-hydrogen atom in the system OCCH to a carbon-carbon double bond that forms part of a conjugated system of the general formula CCCO in an acceptor The condensation takes place under the influence of alkaline reagents, typically alkali metal alkoxides The range of addends is very broad Typical acceptors are alpha, beta-unsaturated aldehydes, keotnes, and acid derivatives As an extension of the original scope, the Michael condensation has come to be understood to include addends and acceptors activated by groups other than carbonyl and carboxalkoxy The wider scope is encompassed in this survey


Keywords:

Michael reaction;
side reaction;
adduct;
bridged intermediates;
cyclopropane derivatives;
Michael condensation;
ketones;
esters;
cycloalkanones;
cycloalkenes;
Robinson's modification;
aromatic rings systems;
rings;
pyrroles;
piperidines;
pyrrolizidines;
amino salts;
experimental conditions

W. Gruber

Papers

Lithiumreaktionen anα-Picolinen

Synthese des d-Pseudoconhydrins

Synthese von Visnagin

Reduktionen an Diazoketonen

ber Kondensationen von Cyanacetamid mit aliphatischen 1,3-Dicarbonylverbindungen: II. Mitteilung ber Pyridinderivate