Ionic liquid mediated and promoted one-pot green synthesis of new isoxazolyl dihydro-1H-indol-4(5H)-one derivatives at ambient temperature

Abstract

We report a mild, inexpensive, fast, highly efficient, and eco-friendly protocol for the synthesis of new isoxazolyl dihydro-1H-indol-4(5H)-ones by a catalyst-free, one-pot three-component reaction of 4-amino-3-methyl-5-styrylisoxazoles, dimedone, and 2-chloroacetophenones under 1-methyl imidazolium tetraflouroborate ([HMIm]BF₄) as task-specific ionic liquid at room temperature. The important aspects of the present methodology are: use of green solvent, short reaction time, catalyst free, compatibility with wide range of substrates, ease of recovery, reusability of reaction medium, and good yields.

Keywords:

• Isoxazolyl dihydro-1H-indol-4(5H)-ones
• one-pot synthesis
• [HMIm]BF₄
• green synthesis

Public Interest Statement

The reported method provides wide scope and quick access to new isoxazolyl dihydro-1H-indol-4(5H)-one derivatives in good to excellent isolated yields within a short period of time from one-pot three-component reaction of 4-amino-3-methyl-5-styrylisoxazoles, dimedone, and 2-chloroacetophenones using 1-methyl imidazolium tetraflouroborate [HMIm]BF₄ as task-specific ionic liquid at room temperature. Major advantages of the present methodology are: use of green solvent, short reaction time, catalyst free, compatibility with wide range of substrates, ease of recovery, reusability of reaction medium, and [HMIm]BF₄ acid as an alternative solvent and catalyst. Hence, the present method meets the concept of Wender’s “ideal synthesis.” Finally, it is concluded that the present method is an attractive addition to the sustainable chemical processes.

Additional information

Notes on contributors

Nagi Reddy Modugu

Nagi Reddy Modugu was born in Hyderabad (India). He received his MSc from Kakatiya University in 2007 and PhD in Organic Chemistry from Kakatiya University, India, in 2011. He then worked as a postdoctoral fellow or research scientist at the University of Hyderabad, India and National Tsing Hua University, Taiwan. Then, he returned to India and joined as a senior scientist at CSIR-IICT Hyderabad. He has more than 10 years of research experience; he has published more than 40 papers in National and International journals. His current research interest focuses on total synthesis of bioactive natural products and synthesis of new isoxazole derivatives.

Praveen Kumar Pittala

Praveen Kumar Pittala obtained his MSc degree in Organic Chemistry from Osmania University (India). He is currently a PhD student under the supervision of Nagi Reddy Modugu at CSIR-IICT Hyderabad, India. His research focuses on the development of new isoxazole derivatives and their biological activity.