Quaternary ammonium compounds (QACs) belong to a well-known class of cationic biocides with a broad spectrum of antimicrobial activity. They are used as essential components in surfactants, personal hygiene products, cosmetics, softeners, dyes, biological dyes, antiseptics, and disinfectants. Simple but varied in their structure, QACs are divided into several subclasses: Mono-, bis-, multi-, and poly-derivatives. Since the beginning of the 20th century, a significant amount of work has been dedicated to the advancement of this class of biocides. Thus, more than 700 articles on QACs were published only in 2020, according to the modern literature. The structural variability and diverse biological activity of ionic liquids (ILs) make them highly prospective for developing new types of biocides. QACs and ILs bear a common key element in the molecular structure–quaternary positively charged nitrogen atoms within a cyclic or acyclic structural framework. The state-of-the-art research level and paramount demand in modern society recall the rapid development of a new generation of tunable antimicrobials. This review focuses on the main QACs exhibiting antimicrobial and antifungal properties, commercial products based on QACs, and the latest discoveries in QACs and ILs connected with biocide development.
The combined electrolysis of barbituric acids and benzylidenemalononitriles or benzylidenecyanoacetates in methanol in an undivided cell in the presence of sodium bromide results in efficient MIRC (Michael-initiated ring-closure) formation of the corresponding spirocyclopropylbarbiturates in 45-93% yield. The electrocatalytic reaction proceeds smoothly under neutral and mild conditions with benzylidenemalononitriles or benzylidenecyanoacetates bearing both electron-donating and electron-withdrawing groups. NMR and single X-ray diffraction studies indicate that the electrocatalytic MIRC transformation of barbituric acids and benzylidenecyanoacetates results in the stereoselective formation of spirocyclopropanes with an (E)-configuration of aryl and alkoxycarboxylate substituents. The implication of electrocatalysis in the MIRC reaction strategy allows the combination of the synthetic virtues of both methods and accounts for an efficient approach to medicinally relevant spirocyclopropylbarbiturates avoiding inconvenient direct use of molecular halogen or halogenated substrates in accordance with the concepts of modern green chemistry.
This review is concerned with modern trends in the use of electrochemically induced chain reactions in cascade and multicomponent electroorganic synthesis. The review summarizes the data on the use of electrochemically induced chain reactions in cascade and multicomponent organic synthesis, which were published mainly in the last decade.
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