Recent advances in the synthesis of indoles from alkynes and nitrogen sources

Transition metal-catalyzed cyclization reactions of unsaturated substrates have become one of the most important and useful methodologies for the preparation of heterocycles. To this end, the association between alkynes and nitrogen compounds results in versatile substrates for the synthesis of N-heterocycles, including indole derivatives. In order to demonstrate the growth in this area, this review highlights ten years of success in the synthesis of indoles using alkynes and nitrogen sources as substrates in the cyclization reactions catalyzed by metals. We believe that summarizing these methods would be very useful for the chemists who are interested in the synthesis of N-heterocycles.