A Rapid and Highly Efficient Microwave-Promoted Four-Component Domino Reaction for the Synthesis of Novel Spiro[benzo[a]chromeno[2,3-c]phenazine] Derivatives Under Solvent-Free Conditions

ABSTRACT

p-Toluenesulfonic acid was applied as an efficient, non-toxic and solid acid catalyst for the one-pot, four-component condensation between 2-hydroxy-1,4-naphthoquinone, benzene-1,2-diamine, cyclic 1,3-dicarbonyl compounds and isatin or ninhydrin to afford the corresponding novel spiro[benzo[a]chromeno[2,3-c]phenazine] derivatives via a new two-step domino protocol under conventional heating and microwave irradiation. This solvent-free process produces biologically considerable heterocycles with the formation of five new bonds (two C–C, two C˭N, and one C–O) and two new rings in a single operation and this effective green process provides considerable advantages such as: operational simplicity, very short reaction time, high yields, absence of any tedious process or purification, and it avoids hazardous reagents/solvents.

KEYWORDS:

• Microwave irradiation
• multi-component domino reactions (MDRs)
• p-toluenesulfonic acid
• spiro[benzo[a]chromeno[2,3-c]phenazine]

Funding

We gratefully acknowledge the financial support from the Research Council of the Young Researchers and Elite Club, Yazd Branch, Islamic Azad University, Yazd, Iran, and Science and Art University of Yazd, Iran.