Structure and tautomeric transformations of 3-substituted 4-hydroxycoumarins (Review)

The structures of pharmacologically active derivatives of the 4-hydroxycoumarin series used therapeutically and for medical hygiene are discussed. It is shown that different structures can be obtained in the crystalline state and in solutions by gradual increases in the distance of the position 3 acyl group of 4-hydroxycoumarin from the aromatic system resulting from the introduction of one or more methylene groups. Tautomeric transformations are discussed, along with the conditions for condensation of these compounds. Reports of the synthesis, purification, pharmacological activity, and mechanisms of action of substances of this medicinal group are presented.