**1.2 Water as a solvent in the synthesis of heterocycles**

Water plays a dominant role as a solvent for the development of numerous heterocycles by replacing the use of hazardous organic solvents. Despite its overwhelming advantages as reaction solvent for organic synthesis, poor solubility of many organic compounds in water limits its use under standard conditions. However, when used in high temperature and pressure conditions, it undergoes a change in its properties and can act as a potent solvent for good number of organic reactions [9]. Owing to tremendous potential of water as a medium for production of heterocyclic moieties, in this chapter, we have tried to compile the 'in water' synthesis of fivemembered heterocycles.
