Cascade reactions as efficient and universal tools for construction and modification of 6-, 5-, 4- and 3-membered sulfur heterocycles of biological relevance

Sulfur-heterocycles are found in nature and they are recognized by biological systems as effective pharmacophores inducing anticancer, antimicrobial, antiviral, anti-diabetic activities via e.g. blocking functionality of many enzymes and receptors. Due to the biological importance of sulfur heterocycles, novel and efficient synthetic strategies, opening the access to regio- and stereoselective construction and functionalization of these scaffolds are in high demand. The advantages and some limitations of tandem strategies are discussed in view of challenges related to the construction of adequately functionalized or fused main heterocyclic sulfur frameworks of biological interest. In addition, examples of sulfur-heterocycles of important biological potency as well as domino reaction mechanisms revealing novel possibilities and ideas for construction of these attractive molecules, are reviewed. Bibliography presented in this review contains references to papers, which appeared mainly during the period from 2009 to 2018.