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

Abstract

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.