Water-Driven Multicomponent Reactions: A Sustainable Platform for Heterocycle Synthesis

Multicomponent reactions promoted by water have proven to be environmentally friendly strategies towards the preparation of various types of heterocycles. Increasing interest in sustainable processes has prompted the replacement of hazardous organic solvents with water, which is nontoxic, cheap, readily available, and straightforward to use. Moreover, water facilitates the conduct of reactions in milder conditions and sometimes even under no catalysis at all. On the other hand, hydrophobic effect allows for higher concentration of organic molecules, thus speeding up their reaction, while hydrogen bonding stabilizes intermediates and transition states. The aim of the current mini-review is to provide an overview of recent developments in this rapidly growing area of chemistry, paying particular attention to the mechanism of water-promoted MCRs and catalysts involved in them. Besides that, the relevance of this area to green chemistry will be highlighted.