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A mild and effective method was developed for the construction of heterocyclic building blocks 3-hydroxyisoindolin-1-ones via a metal-free tandem transformation with excellent regioselectivity. Significantly, the strategy presents an atom-economical and environmentally friendly transformation, in which two new C–N bonds and one C–O bond are formed in water from two simple starting materials. Moreover, a broad spectrum of substrates can participate in the process effectively to produce the desired products in good yields.

A green, rapid, and efficient method was developed for synthesizing quinazolinone derivatives from substituted 2-halobenzoic acids and amidines via microwave-assisted iron-catalyzed cyclization with or without ligand in water (methods A and B) or DMF (methods C and D). With these methods, moderate to high yields of the desired products can be obtained from even inactive substrates, such as guanidines. To the best of our knowledge, this is the first report on the synthesis of N-heterocyclic compounds by iron-catalyzed C–N coupling in aqueous media.

Using [Au(PPh3)]Cl/Ag2CO3-catalyzed 5-endo-digcyclization in water under microwave irradiation, we developed a fast and green route to prepare indole-1-carboxamides from N′-substituted N-(2-alkynylphenyl)ureas. The described method is tolerant to a variety of functional groups, including N′-aryl, alkyl, heterocyclic, various N-(substituted-2-ethynylphenyl) and N-(2-ethynylpyridin-3-yl)ureas and affords moderate to high yields of the desired products.