Efficient microwave-assisted diastereoselective synthesis of indole-based 4,5-dihydrofurans via a one-pot, three-component reaction in water

Abstract

The combination of two or more different heterocyclic moieties in a single molecule would enhance biological activity significantly. The indole and furan scaffolds are promising candidates in drug design, and they have been widely found in natural products and therapeutic agents. Owing to their pharmaceutical importance, there is an urgent need to design rapid, efficient and environmentally benign protocols for the synthesis of indole–dihydrofuran biheterocycles. Herein, we have developed a novel ecofriendly approach for the diastereoselective synthesis of indole-based 4,5-dihydrofurans through a three-component reaction of 3-cyanoacetyl indoles with various aldehydes and N-phenacylpyridinium bromides in the presence of potassium carbonate as an inexpensive and non-toxic base in water under low power microwave irradiation. The findings show that aromatic and heteroaromatic aldehydes tolerated well in this reaction. The products were obtained in 85–98% yields in 4–20 min. The advantages of this method consist of the environmental friendly reaction conditions, use of green solvent and safe base, availability of raw materials, wide range of usable substrates, short reaction times, excellent yields and absence of any tedious workup or purification.